JP2014529280A - Renewable energy power generator and method of operating the same - Google Patents

Abstract

A regenerative energy power generator (for example, a wind power generator) includes a hydraulic transmission that includes a hydraulic pump that is driven by a rotating shaft coupled to a rotor, and a hydraulic motor that drives a generator for supplying power to an electric power system. I have. The transmission controller limits the torque generated by the hydraulic motor, for example, to prevent the generator from stepping out due to a decrease in generator terminal voltage or a decrease in field strength of the hydraulic motor due to an accident. A torque limiter is included. The renewable energy type power generation apparatus has an effect that it is possible to avoid the risk of step-out during operation even if the generator is directly connected to an electric power system. [Selection] Figure 1

Description

  The present invention relates to the field of renewable energy generators configured to receive energy from a renewable energy source and comprising at least one generator that is driven by a hydraulic transmission to supply power to a power system. Examples of the regenerative energy type power generator include a wind power generator that receives energy from wind or a tidal power generator that receives energy from tidal current.

WO 2011/147996 and WO 2011/147997 (Caldwell et al.) Disclose turbine generators that use a generator driven by a hydraulic transmission to supply power to the system. The rotating shaft receives energy from the wind via a rotor having blades and drives a hydraulic pump. The hydraulic pump receives hydraulic oil from the low pressure manifold and supplies pressure oil to the high pressure manifold.
At least one hydraulic motor receives pressure oil from the high pressure manifold, and drives the generator through the shaft by the energy of the pressure oil.

  The hydraulic pump and the hydraulic motor are variable displacement types, respectively, and the displacement volume of the hydraulic pump and the motor is controlled to optimize the generator. In order to increase the efficiency of power generation, it is important to control the torque of the rotor blade so that the optimum torque changes according to the wind speed. This is done by controlling the displacement of the hydraulic pump and the pressure of the high pressure manifold. The displacement of the hydraulic motor is controlled to limit the torque applied to the generator.

  When supplying power to the system, a synchronous generator that can be connected to the power system without using a power converter is preferably used. If a synchronous generator is used, power loss can be reduced and generator efficiency can be improved. In particular, the rotor of the synchronous generator rotates accurately at the frequency of the power system. For example, in a 4-pole generator and a 50 Hz system, the rotor rotates at 1500 rpm. The torque acting on the generator rotor from the prime mover increases the load angle (phase angle between the rotor and the rotating magnetic field from the stator windings) until the magnetic torque matches the prime mover torque. Due to the constant terminal voltage and field current, the relationship between the load angle and the torque is approximately a sine wave. The generator torque is proportional to the field current and terminal voltage through the generator rotor field circuit. The strength of the rotating magnetic field determines the maximum absorption torque of the generator. If the torque increases beyond the maximum absorption torque value (load angle 90 °), the generator will step out. This is an event that significantly damages the generator and must be avoided.

  For example, a power system accident may occur due to a lightning strike, a discharge between power supply conductors caused by a strong wind, or a short circuit in a circuit current of an electrical device due to dielectric breakdown or other electrical or mechanical failure. In most cases, when an accident occurs, the terminal voltage drops to 0 and the current increases rapidly. When such an event occurs, the resistance torque decreases in a very short time, for example, about several milliseconds. Since the drive of the rotor is maintained by the driving force, the rotor can quickly exceed the synchronous speed, and a pole slip can occur instantaneously.

  Furthermore, when the adjusting device is set incorrectly, step-out may occur even in the vicinity where no power system fault has occurred. For example, a power generator generally includes a synchronous generator and an automatic voltage regulator. This regulator changes the field current of the generator in order to adjust the output voltage or power factor of the generator. In setting the voltage control mode, when the terminal voltage is high and the generator is operating at high power, the regulator reduces the field current, thereby reducing the electromagnetic coupling between the rotor and the stator, As a result, the terminal voltage may be lowered to such an extent that the generator is damaged.

  The present invention solves the technical problem in the above-described regenerative energy type power generating device to ensure high reliability while preventing step-out and to realize efficient operation. Some embodiments of the present invention prevent step-out in the event of an abnormality (such as a system fault) in the power system. In some embodiments of the invention, step-out is prevented and protected during events that occur during normal operation, not necessarily when the power system is abnormal.

  Here, the volume of the working fluid displaced (accepted or discharged) per unit rotation of the rotary shaft in the hydraulic pump or hydraulic motor is called the displacement volume of the hydraulic pump and hydraulic motor.

The first aspect of the present invention is:
A regenerative energy power generator that generates power using renewable energy,
An actuating element activated by energy received from a renewable energy source;
A rotating shaft rotated by the regenerative energy received via the actuating element;
A hydraulic transmission including a hydraulic pump driven by the rotating shaft, and a hydraulic motor driven by pressure oil supplied from the hydraulic pump through a high pressure manifold;
A synchronous generator that is driven by the hydraulic motor to generate electric power, is connected to a system without intervention of a power converter, supplies the electric power to the system, and includes a field coil having field strength; ,
In normal operation mode, during normal operation of the renewable energy power generator, while maintaining the frequency of the electric power generated by the generator at the frequency of the grid, the rotational speed changes according to the flow rate of the renewable energy. A transmission controller configured to control the hydraulic transmission to adjust a displacement volume of each of the hydraulic pump and the hydraulic motor such that the rotating shaft rotates, and
The transmission controller
Taking into account the pressure of the high-pressure manifold and the torque limit that is related to the maximum torque allowed by the generator to prevent step-out and that depends on the measured values of the field strength and the terminal voltage of the generator , characterized in that it comprises a motor required value determining unit for determining a request value D _m of the displacement volume of the hydraulic motor.

  This is related to the maximum torque allowed for the generator to prevent step-out, taking into account torque limits that depend on both field strength and generator terminal voltage measurements, and this torque limit. Step-out can be prevented by limiting the maximum torque in consideration of the above. By providing the torque limit, it is possible to prevent the torque generated by the hydraulic motor from exceeding the torque limit.

  The field strength depends on the field current and the field voltage. Typically, the torque limit is determined depending on a measurement of at least one parameter related to field strength. In the case of a brushless generator, the field current is usually measured along with the field voltage, and the torque limit depends on the measured field current. In this case, it is difficult to directly measure the field current. However, since the field current or field voltage of the exciter and the rotation speed can be measured, the field current of the main generator can also be obtained therefrom. Therefore, the torque limit is determined in consideration of the field current and / or voltage of the exciter and the rotation speed. The exciter functions as an amplifier. The excited field current is controlled and measured and converted to an estimate of the generator main field current.

  In some embodiments, the field strength is adjusted by control of the field current (directly or via an exciter). Since the field resistance is a fixed value, the field voltage and field strength can be obtained from the field current.

  Since the hydraulic motor has a motor rotating shaft coupled to the generator rotor, the displacement volume of the hydraulic motor is related to the frequency of the power generated by the generator. However, the number of poles of the generator, the number of periods of the working chamber volume per unit rotation of the motor rotating shaft (usually one), and (not a desirable form) are interposed between the motor rotating shaft and the generator rotor. The ratio is not necessarily 1: 1 because of the gears used.

Displacement of the hydraulic motor is adapted adjustable by the request value D _m of the displacement of the hydraulic motor. Demand value D _m is required to a unit rotation per motor shaft (hydraulic oil) may be a capacitor. The measured value of the rotational speed of the motor shaft is usually taken into account when determining the required displacement volume.

Required motor value determination unit, and the standard required value calculating unit for calculating a required value D _m of the displacement of the hydraulic motor in the normal operation mode, when the maximum torque is not limited to limit the calculated required value And a torque limiter. Typically, the motor request value determination unit calculates the request value in consideration of maintaining the pressure of the high-pressure manifold within the limit.

  The required motor value determination unit may be configured (as programmed) to limit the rate of change of the displacement of the hydraulic motor.

  Ratio restrictions may be available depending on the situation. The rate of change of torque by the hydraulic motor can cause step-out. The field strength of the generator changes according to the torque generated by the motor. For example, the torque generated by the motor may affect the field current defined by the power factor controller and / or the automatic voltage regulator and the output that affects the field strength. As a result, depending on the situation, there may be a feedback loop between the torque generated by the motor and the field voltage. In any case, the actual maximum value of the rate of change of the field current is derived, so that the rate of change can prevent step-out. The field current of the generator changes in torque that is increased by the motor in advance or simultaneously.

  Typically, a regenerative energy generator includes a field coil voltage regulator for adjusting the field coil voltage. The terminal voltage of the generator is usually determined by the pressure of the system linked to the generator.

  The torque limit may be configured to depend on a measured value of at least one parameter related to the field strength and / or a measured value of the terminal voltage of the generator.

  The torque limit may further depend on the load angle of the generator and / or the reactance of the field coil winding.

The displacement of the hydraulic motor may be limited to the torque limit divided by the pressure of the pressure oil supplied to the hydraulic motor (usually coincides with the pressure of the high pressure manifold).

  The torque limit takes into account stored data associated with parameters related to the terminal voltage of the generator and the field strength (eg, field current, exciter current, etc.) that can cause step-out torque. May be determined.

  The stored data may be model parameters calculated to determine the torque limit. The stored data may include a look-up table. Model parameters or look-up tables indicate that the displacement of the hydraulic motor, terminal voltage and field strength (eg, constant field current or constant exciter current, etc., if necessary) until out-of-step occurs It may be obtained from experiments that increase.

  The torque limit may be set so that the torque of the hydraulic motor is maintained below a maximum torque at which a step-out occurs with at least a preset margin. The torque limit is associated with the maximum torque (eg, proportionally or within a fixed range) and is typically less than the maximum torque.

The transmission controller
A torque target value determination unit configured to determine a torque target value of the hydraulic pump based on an optimum torque of the rotating shaft rotating at a turbine speed in a normal operation mode;
In normal operation mode, the pump configured requested value determining unit to determine the required value D _p of displacement of the hydraulic pump on the basis of the torque target value of the hydraulic pump,
Wherein the pump control unit for the displacement of the hydraulic pump is adjusted so that the desired value D _p, may be included.

Furthermore, the renewable energy type power generator is
A terminal voltage sensor for measuring the terminal voltage of the generator;
An exciter for supplying a field current to the field winding of the synchronous generator;
An exciter controller configured to control the exciter based on a difference between the terminal voltage detected by the terminal voltage sensor and a target value of the terminal voltage may be further provided.

  The exciter controller increases the field current rapidly after the terminal voltage of the synchronous generator has decreased due to an abnormal event in the transmission line from the system or from the synchronous generator to the system. The exciter may be controlled as described above.

  When an abnormality occurs in the transmission line or the power system, the generator terminal voltage decreases instantaneously, and the electrical output (active power) of the generator also decreases instantaneously. Therefore, the mechanical input from the hydraulic motor becomes excessive with respect to the electrical output of the generator, the rotor of the synchronous generator is accelerated, and the synchronous generator may be stepped out. Therefore, immediately after the terminal voltage of the synchronous generator decreases due to the occurrence of an abnormal event in the transmission line or power system, increasing the field current increases the generator internal induced voltage and increases the electrical output of the generator. To do. Therefore, the synchronization force of the synchronous generator is increased, the first wave fluctuation of the synchronous generator after the occurrence of the abnormal event is suppressed, and the transient stability is improved. In this way, the step-out of the synchronous generator is prevented.

  Furthermore, the control of the exciter for improving the transient stability can be suitably realized by an excitation method (for example, a thyristor excitation method) having a very fast response speed called a super fast response excitation method.

  The exciter controller increases the field current when the internal phase difference angle of the synchronous generator increases after the field current increases by the exciter, and the internal phase difference angle of the synchronous generator increases. The exciter may be controlled so that the field current decreases when the field current decreases.

If the field current is increased immediately after the terminal voltage is reduced due to the occurrence of an abnormal event, the first wave fluctuation of the synchronous generator is suppressed and the transient stability is improved as described above. There is a risk of deteriorating the steady state stability after one wave shake. Therefore, by increasing the field current when the internal phase difference angle is increased and decreasing the field current when the internal phase angle is decreased, it is possible to quickly suppress the oscillation of the synchronous generator and improve the steady state stability. it can.
In addition, the control of the exciter for improving the steady state stability can be suitably realized by a power system stabilizing device (PSS).

The transmission controller has an abnormal event response mode in which the displacement of the hydraulic motor is reduced from a normal operation mode,
The abnormal event response mode may be configured to start when it is detected that the measured value of the terminal voltage of the generator is equal to or less than a threshold value.

  Abnormalities in the power system (eg, system faults) include, for example, short circuits, low voltage events, or abnormalities in the transmission line.

  In the abnormal event handling mode, the transmission controller adjusts a difference between a load torque of the synchronous generator and a torque generated by the hydraulic motor and input to the synchronous generator. The hydraulic transmission may be controlled so as to reduce the displacement of the motor.

Further, the motor required value determination unit, based on the output generated by said synchronous generator in the abnormal event corresponding mode, is configured to determine the demand value D _m of the displacement volume of the hydraulic motor Also good.

  The transmission controller maintains the abnormal event response mode when a measured value of the generator voltage rises above a threshold value, and executes the hysteresis and avoids chattering by the transmission controller. It may be configured to initiate an event response mode.

  The difference between the threshold pressure input to the transmission controller and the value set in the abnormal event response mode is in the range of 5% to 10%.

  For example, in the case of a wind power generator or tidal current power generator, the actuating element may be a rotor. However, other types of actuating elements such as wave power generators are also known. Such an actuating element is configured to actuate (drive) the rotating shaft in response to received energy, for example.

  Typically, the rotor includes at least one blade.

The regenerative energy type power generator further includes a pitch driving mechanism for adjusting a pitch angle of the at least one blade,
The pitch driving mechanism may be configured to change the pitch angle of the at least one blade to the feather side in the abnormal event response mode.

Further, after recovering from the abnormal event, the pitch driving mechanism changes the pitch angle of the at least one blade to the fine side, and the motor request value determination unit is configured to generate electric power generated by the synchronous generator. There may be configured to increase the required value D _m of the displacement volume of the hydraulic motor to increase.

  Further, the renewable energy type power generation device may be constituted by a wind power generation device that generates power using wind that is the renewable energy, and the operating element is a rotor including at least one blade.

  The required value request value of the displacement volume of the hydraulic pump may be limited so that the output obtained from the regenerative energy is limited by the output of the hydraulic motor transmitted to the generator. Normally, the required displacement of the pump decreases with the required displacement of the motor when the controller switches to the abnormal event response mode.

Typically, a hydraulic motor includes a plurality of working chambers whose volumes change periodically, and a plurality of valves for adjusting the flow of hydraulic oil between the low pressure manifold and the high pressure manifold. At least one valve is an electronic control valve associated with the working chamber. The hydraulic motor has a controller for actively controlling the electronic control valve.
The electronic control valve is configured such that the displacement volume of the hydraulic oil is selected via the hydraulic machine in each cycle of the working chamber volume. Typically, at least two valves, each associated with a working chamber, are electronically controlled valves that are controlled by a controller. That is, the low-pressure valve adjusts the flow of hydraulic oil between each working chamber and the low-pressure manifold. Similarly, the high pressure valve regulates the flow of hydraulic oil between each working chamber and the high pressure manifold.

  Typically, the hydraulic oil is a pressure medium fluid. Typically, the synchronous generator is a brushless generator. When the renewable energy power generator is a wind power generator, the wind power generator includes a tower having a height of at least 25 m, a height of at least 50 m, or a height of at least 100 m. The wind power generator may be an offshore wind power generator.

  Thus, according to the renewable energy type power generation device according to the embodiment of the present invention, even if it is a synchronous generator directly connected to the system without going out of step and without going through a power converter, the energy efficiency For improvement, control is possible with high reliability without step-out.

Exemplary embodiments of the present invention will be described with reference to the following drawings.
It is a figure which shows the wind power generator connected with the electric power grid | system which concerns on embodiment of this invention. It is a figure which shows the hydraulic motor used for the wind power generator of FIG. It is a figure which shows the hydraulic pump used for the wind power generator of FIG. It is a schematic block diagram which shows the functional unit of a controller. It is a figure which shows the calculation step in 1 time step of the control algorithm aiming at control of the wind power generator at the time of normal operation. It is a figure which shows the continuation of FIG. 5A.

  In FIG. 1, in one Embodiment of this invention, a wind power generator (WTG, 100) is illustrated as an energy extraction apparatus connected with an electric power grid | system (101). The wind power generator includes a nacelle (103) attached to a tower (105) so as to be rotatable and to which a hub (107) supporting three blades (109) is attached. The three blades (109) and the hub (107) are known as rotors. An anemometer (111) arranged outside the nacelle transmits the measured wind speed signal (113) to a controller functioning as a transmission controller. A rotation speed sensor (115) provided in the nacelle transmits a rotation speed signal (117, current rotation speed of the rotation shaft) to the controller. In one example of the system, the angle of attack of each blade with respect to the wind can be changed by a pitch actuator (119) that transmits and receives a pitch motion signal and a pitch detection signal (121). In addition, this invention is applicable also to the wind power generator which does not have a pitch actuator. The controller is typically a microprocessor or microcontroller configured to execute a stored program in some or all of the functions that can be implemented as an electronic circuit. The controller may be composed of a plurality of microprocessors or microcontrollers that are divided into a plurality and are each configured to partially perform the overall function of the controller.

  The hub is directly connected to the hydraulic pump (129) via a rotor shaft (125) as a rotating shaft that rotates in the rotational direction (127) of the rotor. Preferably, the hydraulic pump has the form shown in FIG. The hydraulic pump and the hydraulic motor are fluidly connected via a high pressure manifold (133) and a low pressure manifold (135), and each high pressure port and low pressure port are connected to each other, and a valve for restricting the flow. Is connected directly in the sense that there is no intervening. A hydraulic transmission (136) is configured by the hydraulic pump, the hydraulic motor, the low-pressure manifold, the high-pressure manifold, and related devices.

  The hydraulic pump and hydraulic motor are directly attached to each other such that the high pressure manifold and the low pressure manifold form between and within them. The charge pump (137) is connected to a low-pressure accumulator (141), and continuously supplies fluid from the reservoir (139) to the low-pressure manifold. The low pressure relief valve (143) is controlled by a controller connected by a heat exchange control line (146), and is connected to a low pressure manifold via a heat exchanger (144) configured to adjust the temperature of the working fluid. The fluid is returned from the reservoir to the reservoir. The smoothing accumulator (145) is connected to a high-pressure manifold provided between the hydraulic pump and the hydraulic motor. The first high-pressure accumulator (147) and the second high-pressure accumulator (149) (both functioning as an elastically deformable fluid holder) are connected to the first cutoff valve (148) and the second cutoff valve (150), respectively. ing. The first and second high pressure accumulators may have different precharge pressures and may include other additional high pressure accumulators to further expand the range of precharge pressures. The states of the first and second shutoff valves are set by the controller using the first shutoff valve signal (151) and the second shutoff valve signal (152), respectively. The fluid pressure in the high pressure manifold is measured by a pressure gauge (154) configured to output a high pressure manifold pressure signal (154) to the controller. The pressure gauge may optionally be configured to measure fluid temperature and output a fluid temperature signal to the controller. The high pressure relief valve (155) connects the high pressure manifold and the low pressure manifold.

  The hydraulic motor is connected to a synchronous generator (157) as a load via a generator shaft (159). The generator is connected to the power system via a contactor (161). The contactor is configured to receive a contactor control signal (162) from the generator and contactor controller (163) and to be able to operate selective connection and disconnection of the generator to the power system. When the generator is connected to the power system by the contactor, the generator is connected to the power system without interposing a power converter that causes a reduction in power generation efficiency. The generator and contactor controller may measure the voltage, current and frequency measurements measured by the power supply sensor (168) and the generator output sensor (170), respectively, as the power supply signal (167) and the generator output signal (169). ) And send them to the controller via the generator and contactor controller signal (175) to control the generator output by adjusting the current and / or field voltage. The generator and contactor controller includes a current regulation module. The current regulation module functions as a power factor controller (164) for matching the power factor of the output from the generator to the system requirements, and typically also functions as an automatic voltage regulator. In the case of a brushless synchronous generator, the power factor adjustment includes field current adjustment performed by an exciter.

  The hydraulic pump and hydraulic motor transmit the instantaneous angular position and rotation speed of each shaft, and the temperature and pressure of the hydraulic oil to the controller. And a controller sets the state of each valve | bulb using a pump operation signal, a pump shaft signal (171), a motor operation signal, and a motor shaft signal (173). The controller uses an amplifier (180) for amplifying the pitch operation signal, the shut-off valve signal, the pump operation signal, and the motor operation signal.

  FIG. 2 shows a hydraulic motor (131) in the form of an electronically commutated hydraulic pump / hydraulic motor, including a plurality of working chambers (202, hereinafter denoted with individual signs A to H). ing. The working chamber has a volume defined by the inner surfaces of the cylinder (204) and the piston (206). The piston is configured to reciprocate within the cylinder in response to a periodic change in the volume of the working chamber. The rotating shaft (208) is rotated by a piston via an eccentric cam (209). The rotating shaft is connected to the generator shaft (159) and rotates with the generator shaft. The hydraulic motor may have a plurality of banks spaced apart in the axial direction. The plurality of banks are provided in a working chamber driven by the same shaft by similarly spaced eccentric cams. The shaft position and speed sensor (210) detects the instantaneous shaft angular position and number of revolutions and activates each via the signal line (211) as several motor motion and motor shaft signals (173). The instantaneous phase in the chamber cycle is transmitted to the determinable controller (112). Typically, the controller is a microprocessor or microcontroller configured to execute stored programs. The controller may be composed of a plurality of microprocessors or microcontrollers that are divided into a plurality and are each configured to partially perform the overall function of the controller.

  The working chamber is associated with low pressure valves (LPVs) in the form of electronically actuated face seal poppet valves (214). The low pressure valve faces the working chamber side associated therewith and is controlled to selectively seal the flow path extending from the working chamber to the low pressure line (216). The channel generally functions as a channel network or a fluid reservoir, and may be connected to one or a plurality of working chambers. Alternatively, as illustrated, the low-pressure manifold ( 135) may be connected to a low pressure port (217) which is fluidly connected to. The low pressure valve is passively designed to allow fluid to be transferred between the working chamber and the low pressure manifold when the pressure in the working chamber is lower than or equivalent to the pressure in the low pressure manifold, i.e. during the suction process. It is a normally open solenoid valve configured to open. In addition, the low pressure valve prevents fluid from being transferred between the working chamber and the low pressure manifold under the control of the controller via the low pressure valve control line (218, line for transmitting and receiving motor operation and motor shaft signal 173). It also has a configuration that can be selectively closed. As an alternative, a normally closed solenoid valve may be employed.

  Furthermore, the working chamber is also associated with high pressure valves (HPVs) (220) having the form of pressure activated delivery valves. The high-pressure valve opens outward from the working chamber, and can control the closing of the flow path extending from the working chamber to the high-pressure line (222). The channel functions as a channel network or a fluid reservoir, and may be connected to one or a plurality of working chambers, or fluidly connected to the high-pressure manifold (133) as illustrated. May be connected to the high pressure port (224) to be connected. The high pressure valve functions as a normally closed differential pressure check valve configured to passively open when the pressure in the working chamber exceeds the pressure in the high pressure manifold. Further, the high pressure valve is configured to be selectively kept open under the control of the controller via the high pressure valve control line (226, a line for transmitting / receiving the motor operation and motor shaft signal 173). Also good. As an alternative, a normally closed solenoid valve may be employed. Normally, the high pressure valve cannot be controlled by the controller against the pressure of the high pressure manifold. As an additional configuration, the high pressure valve may be openable under the control of the controller when the high pressure manifold, rather than the working chamber, is at high pressure. Alternatively, it may be partially openable. For example, the high pressure valve may be configured to be openable by a method disclosed in International Publication No. 2008/029073 or International Publication No. 2010/029358.

  For example, in the content disclosed in European Patent Application No. 0361927, European Patent Application No. 0494236 and European Patent Application No. 1537333, in normal mode control, the controller is connected to the hydraulic motor. The flow path to the low pressure manifold is such that the low pressure valve or valves are actively closed in a short time before the minimum volume within the working chamber cycle and the fluid in the working chamber is compressed by the remainder of the compression process. And the total displacement volume of the fluid from the high pressure manifold is selected. The high pressure valve is opened when the differential pressures are equal, and a part of the fluid flows into the working chamber through the high pressure valve. The controller then actively maintains the high pressure valve open until it is close to the maximum volume in the working chamber cycle. At that time, fluid flows from the high-pressure manifold into the working chamber, and torque is applied to the rotating shaft. In the selective pump mode, the controller enters the low pressure manifold by actively closing one or more low pressure valves until the hydraulic motor is typically close to its maximum volume in the working chamber cycle. The fluid flow through the high pressure valve in the next compression step (but the high pressure valve does not remain actively open) and selects the total displacement volume to the high pressure manifold It is supposed to be. The controller selects a low pressure valve closing and high pressure valve opening sequence, or a number thereof, for the purpose of creating fluid flow and generating shaft torque to achieve the selected total displacement. Similarly to the determination of whether the low pressure valve needs to be closed or whether the open state needs to be maintained, the controller changes the phase when the high pressure valve is opened, thereby allowing fluid from the high pressure manifold to the low pressure manifold, or vice versa. To control the total displacement of the fluid flow.

  The arrows of the ports (217, 224) indicate the direction of fluid flow in the motor mode. The flow direction in the pump mode is reversed. The pressure relief valve (228) may be configured to protect the hydraulic motor from damage.

  FIG. 3 is a schematic view showing a part (301) of a hydraulic pump (129) provided with an electromagnetic valve. The hydraulic pump includes a plurality of working chambers (303) arranged radially. However, FIG. 3 illustrates only three working chambers among the plurality of working chambers. Each working chamber has a volume defined by the inner surfaces of the cylinder (305) and the piston (306). Here, the piston is driven by the ring cam (307) via the roller (308). The piston is configured to reciprocate in the cylinder so as to periodically change the volume of the working chamber. The ring cam may be attached to a shaft (322) connected to the rotating shaft (125) and configured to be divided into a plurality of segments.

  The hydraulic pump may have one or more banks in which working chambers are arranged radially. The pressure of the fluid in the low-pressure manifold and the working chamber is larger than the pressure around a ring cam or a spring (not shown) for maintaining contact with the ring cam of the roller. The shaft position and speed sensor (309) detects the instantaneous angular position and the number of rotations of the shaft, and transmits them to the controller through an electrical connection (311, pump operation and pump shaft signal 171 transmission / reception line). Thereby, the controller can determine the instantaneous phase in the cycle of each working chamber.

  Each working chamber includes a low pressure valve (LPV) in the form of an electronically actuated face seal poppet valve (313). This valve faces the working chamber and can be controlled to selectively seal the flow path extending from the working chamber to the low-pressure line (314). The channel generally functions as a channel network (or fluid reservoir) (in the pump mode). The low pressure line is fluidly connected to the low pressure manifold (135). The low pressure valve is a normally open solenoid valve. The low pressure valve should open passively when the pressure in the working chamber is lower than the pressure in the low pressure line, i.e. during the suction process, so that fluid can be transferred between the working chamber and the low pressure manifold. This is a normally open solenoid valve. In addition, the low pressure valve prevents fluid from being exchanged between the working chamber and the low pressure line under the control of the controller via electrical low pressure valve control signals (315, pump operation and pump shaft signal 171). It also has a configuration that can be selectively closed. As an alternative, the electrical control valve may be a normally closed solenoid valve.

  In addition, the working chamber includes high pressure valves (HPVs, 317) in the form of pressure activated delivery valves. The high-pressure valve faces outward from the working chamber and can control the closing of the flow path extending from the working chamber to the high-pressure line (319). In addition, the said flow path functions as a flow path network or a fluid storage part, and is fluidly connected with the high voltage | pressure manifold (133). The high pressure valve functions as a normally closed differential pressure check valve configured to passively open when the pressure in the working chamber exceeds the pressure in the high pressure manifold. In addition, the high pressure valve is selectively maintained under the pressure of the working chamber when the high pressure valve is opened under the control of the controller via the high pressure valve control signal (321, pump operation and pump shaft signal 171). You may be comprised so that. The high pressure valve may be openable under the control of the controller when the high pressure manifold rather than the working chamber is at high pressure.

  For example, in the contents disclosed in EP 0361927, EP 0494236 and EP 1537333, in normal mode control, the controller is connected to the high pressure manifold. The displacement volume of the fluid is selected. Typically, close to the maximum volume in the working chamber cycle, the one or more low pressure valves are actively closed to close the flow path to the low pressure manifold, thereby closing the high pressure valves in the next compression step. The fluid is sent out to the outside. In order to achieve the selected total displacement volume, a sequence of low pressure valve closings, or the number thereof, for the purpose of creating a fluid flow and applying torque to the shaft (322) is selected. Similarly to determining whether the low-pressure valve needs to be closed or whether the open state needs to be maintained, the controller changes the phase when the low-pressure valve is closed, thereby allowing the total displacement of fluid from the low-pressure manifold to the high-pressure manifold. It is possible to control to select.

  FIG. 4 is a diagram showing a schematic configuration of a functional unit of the controller (112). The functional unit may include computer program code instructions stored in an electronic circuit or computer readable medium and executable by a computer processor.

The controller (112) functioning as a transmission controller includes a torque target value determination unit (500). Torque target value determination unit, taking into account the optimum torque of the rotary shaft depending on the current rotational speed W _r, is configured to determine a torque target value of the hydraulic pump. The torque target value is an output to the pump request value determination unit (502). The pump demand value determination unit is used to determine the exact pump demand value D _p required to obtain a torque taking into account the current system pressure P _s Functional expression). The pump request value _Dp is an output to the pump control unit. The pump control unit actively controls the low pressure valve of the hydraulic pump by outputting a suitable control signal to select the displacement of the hydraulic pump corresponding to the required value.

  The rotational speed of the rotor shaft (125) varies according to the wind speed (and the resulting fluid velocity of energy received from the wind). However, the exact speed corresponds to the system pressure, the desire to maintain the system pressure within an acceptable range, the start or stop of the equipment, or other reasons (for example, gusts or other wind turbines) Depends on various factors including temporary demands for system pressure adjustment due to operation, etc.).

The controller further includes a standard motor required value determination unit (506).
The standard motor requirement value determination unit is configured to determine the motor displacement target value D _m in consideration of the instantaneous system pressure P _s (pressure of the high pressure manifold) except when a torque limit is applied. Has been. Although not the main configuration of the present invention, in some embodiments, as shown below, a torque target value determination unit (500) for determining a torque target value of the hydraulic pump, for example, within a specified range There may be some interaction with the standard motor requirement determination unit (506) for maintaining the system pressure.

Standard motor required value determination unit (506), during normal operation, is configured to be capable of communicating with the motor control unit (508), it is configured to output the calculated motor displacement setting D _m. Motor control unit, for the purpose of adjustment of the displacement volume of the hydraulic motor in response to motor displacement setting D _m, to produce a low pressure valve and the high pressure valve control signal in each cycle of working chamber volume of the motor.

  However, a torque limiter (510) is also provided that operates to ensure the displacement of the motor so as not to cause pole slip. The torque limiter has access to a torque value database (512) that stores the field current of the generator (which determines the magnetic field strength) and the terminal voltage value of the generator where out-of-step may occur. It is configured. The function of the torque limiter will be described in detail below. Both the torque target value determination unit (500) and the torque limiter (570) function as a motor request value determination unit.

  FIG. 5A and FIG. 5B (continuation of FIG. 5A) show the procedure in one time step of the control algorithm (400). This control algorithm is executed in the controller (112) in the normal operation mode of the wind turbine generator. Note that the control algorithm may be repeatedly executed.

In step S1, the rotor rotational speed _Wr is calculated from the rotor rotational speed signal (117). Here, since the hydraulic pump and the rotor are directly connected by the rotor shaft, the rotational speed of the hydraulic pump may be measured as an alternative. Next, in step S2, a torque target value _Td is calculated from the rotor rotational speed. As described in WO 2011/147996 and WO 2011/147997 (Caldwell et al.), The torque target value may be set based on an aerodynamic ideal torque. For example, the system pressure is reduced before the wind speed temporarily drops so that more energy can be stored during the wind speed drop.

In step S3, the torque target value is divided by the measured pressure of the high-pressure manifold (obtained from the high-pressure manifold pressure signal 154) to calculate a pump request value D _pump . The pump requirement value is the total displacement of the selected hydraulic pump and is the output (402) of the control algorithm, and in the manner described below, the hydraulic pump low pressure valve (and possibly the high pressure valve). ) Is calculated using a controller for selectively controlling.

In step S4, the controller calculates an output corresponding to the fluctuating energy flow Power _rotor . This can be calculated by several different methods. For example, the output may be calculated using the number of rotations of the hydraulic pump, the total displacement of the hydraulic pump, and the pressure of the high-pressure manifold for calculating the fluid output. Alternatively, the output may be calculated using an aerodynamic torque estimated value T _aero for calculating the rotational speed of the rotor and the mechanical output.

In step S6, for example, by executing a smoothing module such as a first low-pass filter, a value Power _motor obtained by smoothing the fluctuating energy flow Power _rotor is calculated. The designer may select a wind power generator and a smoothing algorithm suitable for the state. This smoothed value is a reference for calculating the total displacement of the working fluid by the hydraulic motor, and is set without considering the influence of the pressure in the high pressure manifold on the total displacement due to its independence. .

In step S7, the headroom torque _Th is calculated. The headroom torque defines a minimum torque for the hydraulic pump. This is applied to properly control the rotor speed during unpredictable gust or wind speed increases. The headroom torque plays the role of the rotational speed of the hydraulic pump.

The rotor torque is generated by a hydraulic pump in which the total displacement per unit rotation (including the set limit value defined by the number and volume of working chambers) is selected, and the lower limit value _Pmin is set by the headroom torque request value. The In step S8, the minimum pressure P _min of the high pressure manifold defined by a lower limit value of allowable pressure range is calculated from the headroom torque T _h. Further, an additional lower limit value P _min is set as the minimum precharge pressure P _{acc, min} of the smoothing means (or the first and second accumulators). When the value is equal to or lower than the lower limit value, the pressure followability of the high-pressure manifold may be insufficient to execute preferable control. Therefore, it is desirable to provide the allowable pressure range and both the lower limit values described above.

In step S9, based on the minimum pressure P _min of the high pressure manifold, the set maximum pressure of the manifold P _max (which functions as the upper limit value of the allowable pressure range), and either the fluctuating energy flow or its smoothed value, A pressure control gain _Kp is calculated.

In step S10, the pressure target value _Pd is calculated from one or more optimum operation points in the wind turbine generator, the control range limit of the wind turbine generator or the minimum pressure requirement.

  The steps so far execute the function of the pump request value determination unit (502). In the subsequent steps, the function of the motor request value determination unit is executed.

Next, in step S11, the controller calculates the motor nominal value D _n of the total displacement volume of the motor (motor required value). The nominal motor value is calculated from the motor rotation number signal (211), the system pressure (for example, the pressure of the high-pressure manifold) signal (154), and the motor output value Power _motor (D _n = Power _motor / W _motor / P _s ).

In step S12, the control algorithm, by multiplying the force control gain K _p to the difference between the measured pressure and the target pressure P _d, the correction value D _b of the motor required value is calculated.

In step S13, the controller, by adding the motor nominal value D _n and the correction value D _b, calculates the motor displacement D _m of the hydraulic motor (motor required value).

During normal operation, the motor displacement target value _Dm is the output of the control algorithm (404). This motor displacement target value is used when the controller selectively controls the valve of the hydraulic motor by the method described above.

In step S14 and step S15, the controller executes the function of a torque limiter. In step S14, the controller calculates the maximum value of the absorption torque of the generator, that is, the torque limit _{TL at} which step-out occurs. This is done by reading the exciter current value I _F (which depends on the field current and field strength) and the generator terminal voltage V _T and extracting the corresponding torque from the database. . Database data can be obtained from empirical or experimental measurements of torque. This torque is the torque at which a step-out occurs in a similar generator when an exciting current and a terminal voltage of the generator are applied.

In step S15, the controller calculates the torque of the generator when the motor displacement target value _Dm is transmitted to the motor control unit. Torque of the generator, determine motor displacement is proportional to the system pressure P _s and the rotational speed w of the motor shaft, when the motor displacement setting D _m has exceeded the torque limit, a torque limiter motor displacement setting It can be done.

In step S16, the controller determines whether to reduce the motor displacement setting D _m in order to limit the torque. When the torque acting on the generator exceeds the torque limit _TL , the motor displacement target value _Dm is reduced. In fact, since the torque within the limits of Rukurimitto T _L (e.g., 5% or 10%, or more) acts on the generator, the torque limiter is generally is ensured.

In some embodiments, the data stored in the database is not a torque limit _TL but a value including a margin. In some embodiments, the desired motor torque is calculated and processed such that it does not exceed the torque limit (eg, by selecting the desired motor torque and the lower limit of the torque limit), and the processed torque is displaced by the motor. used in the calculation of the volume _{D m.}

The final value of the motor displacement D _m in step S17, is outputted to the motor control unit for controlling the timing of the low-pressure valve and the high pressure valve in a continuous cycle of working chamber volume.

In some embodiments, the torque limiter function, by conventional calculation of the motor displacement D _m, but by limiting the slew rate of the output value of the motor displacement D _m, the maximum rate of change of torque acting on the generator Execute. Typically, the allowable slew rate depends on the response speed of the power factor controller and / or automatic voltage regulator.

  The torque limiter is used to avoid step-out during normal operation of the wind turbine generator, for example, when the field strength decreases to maintain the required power factor. However, in some embodiments of the present invention, the torque limiter function is initiated when a system fault is detected that causes a reduction in torque that causes the generator to step out. Such a system fault can be detected from a decrease in the terminal voltage of the generator. In response to detecting a system fault, the wind turbine generator initiates an abnormal event response mode, and in some embodiments activates the torque limiter function only in the abnormal event response mode.

The torque limit function is an especially important function as a response to such a system fault. When a system fault that reduces the terminal voltage of the generator occurs, or when an accident that reduces the field strength occurs, the torque limit _TL is suddenly increased to avoid damage to the generator. You may comprise so that it may fall to.

  The abnormal event response mode (and the abnormal event response mode in which the torque limiter operates in embodiments with a torque limiter) may be triggered, for example, by a drop that exceeds a threshold of the generator terminal voltage. Then, the wind turbine generator may return to the normal operation mode when the terminal voltage of the generator returns after exceeding a threshold value. Typically, a hysteresis may be provided in these controls in order to avoid chattering of the required motor displacement volume sent to the motor control unit.

A generator and contactor controller (163), configured to control the exciter (166) and adjust the field current and field strength via the control signal (165), the generator field current and It is configured to control the field strength. This generator and contactor controller measures the difference between the instantaneous measurement of the generator terminal voltage and the field voltage of the generator when the generator terminal voltage is reduced. Increase the generator field voltage within _TL . The generator and contactor controller controls the exciter so that the field current increases when the internal phase difference angle of the synchronous generator increases and the field current decreases when the internal phase difference angle of the synchronous generator decreases. It is like that.

  Further, according to the present invention, the displacement of the pump of the hydraulic pump is corrected according to the detection of the abnormality. In some embodiments, the feed forward control module reduces the pump displacement of the hydraulic pump after anomaly detection (eg, quickly). Thereby, the energy absorption rate by the hydraulic pump is reduced so that the displacement volume of the motor is reduced, and an excessive increase in pressure of the high-pressure manifold is avoided.

  A skilled engineer will understand that the function of the controller can be realized by computer software or electronic circuitry, or a combination of the two.

  Therefore, the present invention is a wind power generator that can be controlled with high reliability without stepping out in order to improve energy efficiency, even if it is a synchronous generator directly connected to the system without going through a power converter. A device or other power generation device of renewable energy type is provided.

  Further changes and modifications may be made within the scope of the invention disclosed in this specification.

100 Wind turbine generator (renewable energy generator)
101 Power System 103 Nacelle 105 Tower 107 Hub 109 Blade 110 Rotor (Operating Element)
111 Anemometer 112 Transmission controller 113 Measured wind speed signal 115 Revolution meter 117 Revolution signal 119 Pitch actuator 121 Pitch detection signal 125 Rotor shaft 127 Rotor rotation direction 131 Hydraulic motor 133 High pressure manifold 135 Low pressure manifold 136 Hydraulic transmission 137 Charge pump 139 Reservoir 141 Low pressure accumulator 143 low pressure relief valve 144 heat exchanger 145 smoothing accumulator 146 heat exchanger control line 147 first high pressure accumulator 149 second high pressure accumulator 150 second shutoff valve 151 first shutoff valve signal 152 second shutoff valve signal 154 high pressure manifold Pressure signal 155 High pressure relief valve 157 Synchronous generator 159 Generator shaft 161 Contactor 162 Contactor control signal 163 Contactor controller 164 Power factor controller / automatic voltage regulator 165 Generator control signal 166 Exciter 167 Power supply signal 168 Power supply sensor 169 Generator output signal 170 Generator output sensor 171 Pump shaft signal 173 Motor shaft Signal 175 Contactor control signal 180 Power amplifier 202 Working chamber 204 Cylinder 206 Piston 208 Rotating shaft 209 Eccentric cam 210 Shaft position and speed sensor 211 Signal line 214 Low pressure poppet valve 216 Low pressure line 217 Low pressure port 218 Low pressure valve control line 220 High pressure valve 222 High-pressure line 224 High-pressure port 226 High-pressure valve control line 228 Pressure relief valve 301 Hydraulic pump part 303 Working chamber 305 Cylinder 306 Piston 307 Gucam 308 Roller 309 Shaft position and speed sensor 311 Electrical connection 313 Low pressure poppet valve 314 Low pressure line 315 Low pressure valve control signal 317 High pressure valve 319 High pressure line 321 High pressure control signal 322 Shaft 400 Control algorithm 402 Pump required value 404 Motor required value Output, D _m
500 Torque target value determination unit 502 Pump request value determination unit 504 Pump control unit 506 Standard motor request value determination unit 508 Motor control unit 510 Torque limiter 512 Torque limit value database

Claims (19)

A regenerative energy power generator that generates power using renewable energy,
An actuating element activated by energy received from a renewable energy source;
A rotating shaft rotated by the regenerative energy received via the actuating element;
A hydraulic transmission including a hydraulic pump driven by the rotating shaft, and a hydraulic motor driven by pressure oil supplied from the hydraulic pump through a high pressure manifold;
A synchronous generator that is driven by the hydraulic motor to generate electric power, is connected to a system without intervention of a power converter, supplies the electric power to the system, and includes a field coil having field strength; ,
In normal operation mode, during normal operation of the renewable energy power generator, while maintaining the frequency of the electric power generated by the generator at the frequency of the grid, the rotational speed changes according to the flow rate of the renewable energy. A transmission controller configured to control the hydraulic transmission to adjust a displacement volume of each of the hydraulic pump and the hydraulic motor such that the rotating shaft rotates, and
The transmission controller
Taking into account the pressure of the high-pressure manifold and the torque limit that is related to the maximum torque allowed by the generator to prevent step-out and that depends on the measured values of the field strength and the terminal voltage of the generator , renewable energy power generation device which comprises a motor required value determining unit for determining a request value D _m of the displacement volume of the hydraulic motor.   The regenerative energy power generator according to claim 1, wherein the required motor value determination unit is configured to limit a change rate of the displacement of the hydraulic motor.   The regeneration energy according to claim 1, wherein the torque limit is determined depending on a measured value of at least one parameter related to the field strength and / or a measured value of the terminal voltage of the generator. Type generator.   The regenerative energy power generator according to claim 3, wherein the torque limit further depends on a load angle of the generator and / or a reactance of a field coil winding.   The regenerative energy generator according to claim 3, wherein the displacement of the hydraulic motor is limited to the torque limit divided by the pressure of the pressure oil supplied to the hydraulic motor.   The torque limit is determined in consideration of stored data associated with a parameter related to the terminal voltage and the field strength of the generator so that a torque that may cause a step-out is generated. Renewable energy type power generator described in 1.   6. The regeneration energy according to claim 5, wherein the torque limit is set so that the torque of the hydraulic motor is maintained below a maximum torque at which a step-out occurs at least by a preset margin. Type generator. The transmission controller
A torque target value determination unit configured to determine a torque target value of the hydraulic pump based on an optimum torque of the rotating shaft rotating at a turbine speed in a normal operation mode;
In normal operation mode, the pump configured requested value determining unit to determine the required value D _p of displacement of the hydraulic pump on the basis of the torque target value of the hydraulic pump,
Renewable energy power generating device according to claim 1, characterized in that it comprises, a pump control unit for adjusting so that the displacement volume of said hydraulic pump becomes the required value D _p. A terminal voltage sensor for measuring the terminal voltage of the generator;
An exciter for supplying a field current to the field winding of the synchronous generator;
2. An exciter controller configured to control the exciter based on a difference between the terminal voltage detected by the terminal voltage sensor and a target value of the terminal voltage. Renewable energy type power generator described in 1.   The exciter controller increases the field current rapidly after the terminal voltage of the synchronous generator has decreased due to an abnormal event in the transmission line from the system or from the synchronous generator to the system. The regenerative energy type power generator according to claim 9, wherein the exciter is controlled as described above.   The exciter controller increases the field current when the internal phase difference angle of the synchronous generator increases after the field current increases by the exciter, and decreases the internal phase difference angle of the synchronous generator. The regenerative energy type power generator according to claim 9, wherein the exciter is controlled so that the field current is sometimes reduced. The transmission controller has an abnormal event response mode in which the displacement of the hydraulic motor is reduced from a normal operation mode,
The regenerative energy type generator according to claim 1, wherein the abnormal event response mode is started when it is detected that the measured value of the terminal voltage of the generator is equal to or less than a threshold value.     In the abnormal event response mode, the transmission controller is configured to adjust a difference between a load torque of the synchronous generator and a torque generated by the hydraulic motor and input to the synchronous generator. The regenerative energy generator according to claim 13, wherein the hydraulic transmission is controlled so as to reduce the displacement volume. The required motor value determination unit is configured to determine the required value D _m of the displacement of the hydraulic motor based on an output generated by the synchronous generator in the abnormal event response mode. The regenerative energy type power generation device according to claim 12,   The transmission controller maintains the abnormal event response mode when a measured value of the generator voltage rises above a threshold value, and executes the hysteresis and avoids chattering by the transmission controller. The regenerative energy type power generation device according to claim 12, wherein the regenerative energy type power generation device is configured to start a mode. The actuating element is a rotor having at least one blade;
The regenerative energy type power generator further includes a pitch drive mechanism for adjusting a pitch angle of the at least one blade,
The regenerative energy power generator according to claim 12, wherein the pitch driving mechanism is configured to change the pitch angle of the at least one blade to a feather side in the abnormal event response mode. The actuating element is a rotor having at least one blade;
After recovering from the abnormal event, the pitch drive mechanism changes the pitch angle of the at least one blade to the fine side, and the motor request value determination unit increases the power generated by the synchronous generator. renewable energy power generating device according to claim 12, wherein the set to the displacement arrangement to increase the demand value D _m of the volume of the hydraulic motor so as to.   The regenerative energy type power generator is configured by a wind power generator that generates power using wind that is the renewable energy, and the operating element is a rotor including at least one blade. The renewable energy type power generator described. The required value required value of the displacement volume of the hydraulic pump is limited so that an output obtained from the regeneration energy is limited by an output of the hydraulic motor transmitted to the generator. Item 20. A renewable energy power generation device according to Item 19.

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