JPH0884445A - Energy charging/discharging apparatus with flywheel - Google Patents

Abstract

PURPOSE: To provide an energy charging/discharging apparatus in a simple structure with a flywheel for generating electric energy with good characteristics. CONSTITUTION: An inductor element 13 joined with a flywheel 14 is connected to a local power line 3 with a bidirectional inverter 12 in between. When a power load unit 5 is under a given electric energy level set in accordance with output performance of a power supply, an output frequency is raised above a set value to rotate the inductor element 13 as a motor and store rotational energy in the flywheel 14. When the power load unit 5 is above the given energy level, the inverter 12 generates an output frequency lower than the set value to rotate the inductor element 13 as a generator at the same speed as the flywheel 14. In this case, the stored energy is converted from rotational energy to electric one, and the power is fed to the local power line 3 through the inverter 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is driven by a power system for which the power receiving equipment of a power circuit supplied with electric energy from commercial power is desired to be kept as economical as possible, or a driving machine such as a diesel engine or a gas turbine. A power load device that is most suitable for a power system that is supplied with electrical energy by a generator, for example, when a sudden excessive power supply is required such as a load of a rolling mill or a welding machine. The present invention relates to an energy storage and emission device using a flywheel capable of stably supplying electric power to a vehicle.

[0002]

2. Description of the Related Art In factory facilities and the like, there is a power system in which commercial power is received by a power receiving facility having a predetermined power receiving capability and electric energy is supplied to a power circuit in a premises. Further, there is a power system in which electric energy is supplied by a generator driven by a driving machine such as an internal combustion engine such as a diesel engine or a gas turbine. The above power system is configured as shown in FIG. 4, for example. FIG. 4 (A) shows an example of a commercial power receiving system. In the figure, 1 is a power receiving facility including a transformer, a circuit breaker, meters and the like, and 2 is a commercial power grid power distribution line. . The output of the power receiving equipment 1 is distributed to the premises by a premises distribution line 3 which is a power circuit in the premises.
The premises distribution line 3 is connected to a power load device 5 via a circuit breaker 4. It should be noted that, in FIG. 7A, description of control elements, switches, and the like of the power system is omitted. Although a plurality of power load devices are connected to the local distribution line 3, only one set is shown as a representative in the figure. FIG. 4B shows an example of a closed-circuit power system in which a generator is driven by a driving machine such as a private power generation system.
In the figure, 6 is an AC generator, and 7 is a drive machine for driving the AC generator. The power generated by the AC generator 6 is distributed to the premises by a premises distribution line 8 which is a power circuit in the premises. The local distribution line 8 is connected to the power load device 1 via the circuit breaker 9.
Connected to 0. In FIG. 1B, the description of the control elements of the electric power system, switches, etc. is omitted. Further, although a plurality of power load devices are connected to the local distribution line 8, only one set is shown as a representative in the figure.

There are also means to use flywheels to ensure a stable power supply when the power supply or load is unstable. Techniques for using a flywheel or a flywheel effect in an electric power system include, for example, JP-A-55-58785, JP-A-55-82316, JP-A-4-185233, and JP-A-4-275.
No. 027, JP-A-5-153732, JP-A-5-274049 and the like. Japanese Patent Laid-Open No. 55-57885 discloses a busbar that supplies electric power to an internal pump motor in a reactor vessel.
By connecting a synchronous machine with a large inertia constant, the heat of the core is removed even in the case of a power outage in the plant, and the soundness of the fuel body is maintained. In addition, JP-A-55-823
The device described in Japanese Patent No. 16 operates a synchronous machine having a flywheel as an electric motor for phase shifting at all times, and when the power supply is lost, power is supplied to the frequency converter bus as a generator, thereby reducing the cost of the rotating machine and the circuit. It is intended to construct a buffer that can be reduced. In addition, JP-A-4-18
The thing described in Japanese Patent No. 5233 is a flywheel that is an electric motor when the output of wind power generation is large and a generator when the output of the wind power generator is small in a wind power generation facility that is operated by being connected to a power system of a constant frequency. The kinetic energy stored in is output as electric power in order to smooth the output fluctuation in the variable output operation. Further, the one described in JP-A-4-275027 discloses an AC excitation synchronous machine that is directly connected to a prime mover and constantly generates electric power at a commercial frequency even if the rotation speed of the prime mover fluctuates, and stores and releases fluctuating energy. By combining with an AC excitation synchronous machine with a flywheel for performing the above, it is intended to supply stable power to a load by energy storage of the AC excitation synchronous machine with a flywheel. Further, the one disclosed in JP-A-5-153732 is intended to improve the stability of the electric power system by using a variable speed synchronous machine and a flywheel. Further, the one described in JP-A-5-274049 is
In order to stabilize the power supply, the motor equipped with a flywheel is constantly operated by the inverter, accumulates regenerative energy, and when an instantaneous voltage drop occurs during the operation of various equipment, the inverter responds with the detection signal from the high-speed response voltage drop detection relay. The output frequency is reduced and the regenerative energy of the motor is regenerated to the three-phase AC power source side by the power source regenerative converter to boost the power source voltage and restore the steady voltage.

[0004]

The conventional electric power system as described above has the following problems. In order to withstand a sudden load change, a generator and power receiving capability that can withstand a load that is about twice the steady load are required. This is because, if this is not done, the power receiving capacity may be momentarily exceeded, or the voltage or / and frequency of the generator may fluctuate, and the power quality may deteriorate. The prior art disclosed in the above-mentioned respective publications in which the load machine is equipped with the flywheel does not solve the above-mentioned problems. For example, the one disclosed in Japanese Patent Laid-Open No. 4-185233 operates by detecting an output fluctuation of a wind power generator as seen in its embodiment, and is suitable for a power generator having an unstable output. It can handle it, but it cannot handle sudden changes in load. Further, the one described in Japanese Patent Laid-Open No. 5-274049 is for compensating for a sudden drop in the power supply voltage due to a load change in the power system.
AVR (Automatic Voltage Reg
It is not possible to cope with load fluctuations in a system in which the voltage is stable because the ululator) is functioning. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems (problems) of the conventional one, and to provide an energy storage and emission device by a flywheel for obtaining electric power energy having a simple structure and good characteristics.

[0005]

In order to solve the above problems, in a flywheel energy storage and emission device according to the present invention, an induction machine having a flywheel coupled to a power circuit is connected through a bidirectional inverter. However, under the power load condition of less than the preset predetermined electric energy corresponding to the output capacity of the power supply, the output frequency of the bidirectional inverter is set to a frequency equal to or higher than the preset preset frequency by the power supplied from the bidirectional inverter. The bidirectional inverter operates under the condition that the flywheel connected to the induction machine is operated as an electric motor to store and store the rotational energy, and the preset load is equal to or higher than a preset electric energy corresponding to the output capacity of the power source. Set the output frequency of the (A) Operate as a generator driven by the rotational speed of the wheel, convert the rotational energy stored in the flywheel connected to the induction machine into electrical energy, and release it to the bidirectional inverter, which is then output by the bidirectional inverter. The power circuit is supplied via the. The output frequency of the bidirectional inverter, which is determined under a power load condition of less than a predetermined electric energy set in advance corresponding to the output capacity of the power supply described above, is set higher than a predetermined frequency corresponding to the rotation speed of the flywheel by a predetermined value, and Or, the output frequency of the bidirectional inverter determined under a power load condition equal to or higher than a predetermined electric energy set in advance corresponding to the output capacity of the power supply should be lower than the predetermined frequency corresponding to the rotation speed of the flywheel by a predetermined value. Is desirable.

[0006]

In the present invention, since the configuration is as described above, the frequency of the bidirectional inverter is increased when the power load amount is less than the predetermined amount, so that the induction machine functions as an electric motor and surplus power is consumed. Energy is coupled to the induction machine and stored and stored as rotational energy in a driven flywheel. Also, if the load suddenly becomes excessive,
When the amount of load power increases and exceeds the output allowable amount of the power supply device, the frequency of the bidirectional inverter is lowered, so the frequency of the applied power becomes lower than the rotation speed driven and rotated by the flywheel. The induction machine operates as a generator, converts the rotational energy stored in the flywheel as rotational energy into electric energy, superimposes it on the electric power supplied from the power source, and supplies the electric power to the electric load. When the power load is small, the output frequency of the bidirectional inverter is set higher than the predetermined frequency corresponding to the rotation speed of the flywheel by a predetermined value, and / or when the power load is large. By lowering the output frequency of the bidirectional inverter by a predetermined value from the predetermined frequency corresponding to the rotation speed of the flywheel, the energy storage capacity of the flywheel can be effectively utilized according to the current rotation speed of the flywheel. An efficient energy storage and emission device can be realized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A flywheel energy storage and discharge device according to the present invention will be described with reference to FIG. In the figure, the components corresponding to those of the prior art are denoted by the same reference numerals as those in FIG. In FIG. 1, 1 is a power receiving facility including a transformer, a circuit breaker, and the like, and 2 is a grid power distribution line for commercial power. The output of the power receiving equipment 1 is distributed to the premises by a premises distribution line 3 which is a power circuit in the premises. The premises distribution line 3 is connected to a power load device 5 via a circuit breaker 4. Further, the local distribution line 3 is connected to the first input / output terminal a of the bidirectional inverter 12 via the switch 11. The induction machine 13 is connected to the second input / output terminal b of the bidirectional inverter 12.
A flywheel 14 is coupled to the rotating shaft of 3.
In FIG. 1, description of the control elements of the power generation system, switches and circuit breakers other than those shown in the figure is omitted, and each connection line is also simplified by a single line. Although a plurality of power load devices are connected to the local distribution line 3, only one set is shown as a representative in the figure. The embodiment shown in FIG. 1 shows an example in which the present invention is applied to a power system corresponding to the power system shown in FIG. 4 (A) of the conventional example, and the present invention is further shown in FIG. 4 (B). Fig. 1 when applied to a power system
In the same way as the above, a switch 11 is attached to the local distribution line 8 that constitutes the power circuit.
If the first input / output terminal a of the bidirectional inverter 12 is connected to the second input / output terminal b of the bidirectional inverter 12 and the induction machine 13 with the flywheel 14 is connected, Applicable.

The bidirectional inverter 12 is, for example, the first
The converter function of converting the incoming AC input, which is the frequency of the indoor distribution line 3 connected to the input / output terminal a, into a direct current, and the direct current supplied from the second converter / inverter 12b described later to the frequency of the internal distribution line 3 That is, the first converter / inverter 12a and the first converter / inverter 12a having a function of mutually executing the function of converting the frequency of the received AC power and outputting the frequency to the first input / output terminal a.
The function of converting the direct current converted by the AC into an AC of a frequency determined according to the characteristics of the induction machine 13 and the flywheel 14 and outputting the AC to the second input / output terminal b, and reducing the conversion frequency to induce the induction machine 13 If the is operated as an AC generator, the second
The second converter / inverter 12 having a function of converting this power generation AC input from the input / output terminal b of the above into DC and supplying it to the above-mentioned first converter / inverter 12a.
b, and has a control function, the details of which will be described later.

Next, the general characteristics of the induction machine 13 used in the present invention will be described with reference to FIG. In FIG. 2, the horizontal axis represents the rotational speed of the induction machine, the upper half of the vertical axis represents the output torque of the induction machine, and the lower half of the vertical axis represents the input (absorption) torque of the induction machine. The vertical axis shown in the middle of the horizontal axis of FIG. 2 indicates the frequency of the AC power supplied to the induction machine, that is, the AC frequency input from the bidirectional inverter 12 shown in FIG. Synchronous speed, where the left side of the synchronous speed shows the motor area corresponding to the sliding speed determined by the mechanical load, and the right side of the synchronous speed is the sliding speed caused by the forced mechanical rotation of the induction machine. The corresponding generator area is shown. That is, the induction machine has a mechanical load coupled to the induction machine, and when electric power is supplied, the induction machine drives the mechanical load as an electric motor that rotates at a sliding speed m determined by the characteristics of the induction machine and the mechanical load amount. On the contrary, when the rotation speed of the induction machine is forced to rotate from the mechanism connected to the induction machine and becomes faster than the synchronous speed, the induction machine will have a sliding speed g determined by the characteristics of the induction machine and the electrical load.
It functions as a generator that rotates at and supplies power to the connected power circuit.

Next, the function of the present invention in the embodiment shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a diagram showing an example of a variation state of the power load device 5 shown in FIG. 1, in which the horizontal axis represents time and the vertical axis represents the load amount (load power amount).
The horizontal line in the middle of the vertical axis indicates the reference load level determined by the conditions of this power system. For example, it is a load amount corresponding to the power receiving contract amount of the power receiving facility 1 shown in FIG. 1, and is usually an amount that does not allow the load to absorb power more than the reference load amount. Also, FIG. 4 (B)
In the case of a power generation system such as an in-house power generation system in which electric power is supplied by a generator driven by the drive machine shown in Fig. 6, the amount of electric power that cannot be generated by the generator is normally above this reference load amount. . In FIG.
Switch 11 with power being supplied to the distribution line 3
Is turned on and the load amount is less than the reference load amount as shown in FIG. 3, power is supplied from the local distribution line 3 to the first input / output terminal a of the bidirectional inverter 12, and the bidirectional power (not shown) is supplied. Due to the function of the control function of the inverter 12, the second converter / inverter 12b is operated by the flywheel 14
The frequency that is higher than the frequency at which the rotation speed of the induction machine is the synchronous speed of the induction machine 13 by a slip speed that is preset corresponding to the rotation characteristics of the induction machine 13 is output and supplied to the induction machine 13. Therefore, the induction machine 13 rotates in the electric motor region by using the flywheel as a mechanical load, and the surplus of the electric energy of the local distribution line 3 is stored as the rotational energy of the flywheel.

Next, when the power load device 5 includes, for example, a rolling mill, and a plurality of electric motors for driving a plurality of rollers are simultaneously turned on, as shown at point c in FIG. In addition, a load fluctuation detection function for determining that the load amount exceeds the reference load level, which is installed in advance in the power receiving equipment 1 (not shown), for example, based on the power difference between the received power amount and the reference load (power) amount, is provided. When detected, the control function of the bidirectional inverter 12 not shown causes the second
The converter / inverter 12b of the flywheel 1
A frequency lower than the frequency at which the rotational speed of No. 4 is the synchronous speed of the induction machine 13 by a slip speed preset corresponding to the rotation characteristic of the induction machine 13 is output and supplied to the induction machine 13. Therefore, the induction machine 13 rotates in the generator region using the flywheel as a drive source. Therefore, the electric power generated by the induction machine 13 is input to the second converter / inverter 12b and converted into direct current, and further, the first converter / inverter 12a.
Is converted to the frequency of the grid power distribution line 2 from the first input / output terminal a of the bidirectional inverter 12 to the local distribution line 3
And superimpose it on the received power supplied from the grid power distribution line 2 to bear the shortage of the power load. That is, the rotational energy stored in the flywheel 14 is converted into electric energy and emitted.

The above description shows the basic means and configuration for realizing the technical idea of the present invention, and appropriate element functions corresponding to the scale and conditions of this power system and the conditions of power load. Should be selected, configured, and activated. For example, although it has been described that the fluctuation of the load power is detected by the load fluctuation detection function that determines from the difference power between the received power amount and the reference load (electric power) amount installed in the power receiving equipment 1, the power source of the power system is the internal combustion engine. In the case of a generator driven by an engine, if the response speed of the AVR is fast enough, it is detected from the fluctuation of the power generation frequency due to the response delay of the internal combustion engine, while the response speed of the AVR is slow or insufficient. In such a case, detection may be performed from the fluctuation of the power generation voltage on the premises, or an appropriate means such as measuring and detecting the output current value or the generated power amount of the generator may be set. Alternatively, it may be determined based on the operation status of the power load function. Further, although the frequency supplied from the bidirectional inverter 12 to the induction machine 13 is set according to the rotation speed of the flywheel 14, it is necessary to prevent the frequency from being excessively high or low. The setting upper limit and / or the setting lower limit may be set in advance.
Further, regardless of the rotation speed of the flywheel 14, the induction machine 13 is driven in the electric motor area at a high frequency of a predetermined value set in advance to drive the induction machine 13 in the electric motor area in accordance with the characteristics of the induction machine. You may make it output the low frequency of the preset predetermined value. Further, the setting of the frequency corresponding to the rotation speed of the flywheel and the preset predetermined frequency may be appropriately determined in accordance with the conditions. Although it has been described that the above-described bidirectional inverter 12 is configured by the first converter / inverter 12a, the second converter / inverter 12b, and the control function (not shown), the bidirectional inverter 12 can be configured as shown in the above-described embodiment. Any other suitable configuration may be used as long as it can output an alternating current of a desired frequency with the characteristics of. Further, as the induction machine used when applying the present invention,
Although it is effective to use a squirrel cage induction machine from the viewpoint of reliability and cost, a winding type induction machine may be used and the secondary current control may be added to the above control conditions.

[0013]

Since the present invention is constructed and operates as described above, it has the following excellent effects. The rotational load stored in the flywheel is converted into electric energy when the load suddenly changes, and the electric energy is emitted and superposed on the generated electric power, so that the electric power load can be leveled. Therefore, it is economical because there is no need for the power receiving facility or the power generating facility to handle the maximum load. When the power source is a small amount of back power, such as an in-house power generation system, the amount of power load could be leveled, so
It is possible to obtain a high-quality power supply by eliminating voltage and frequency fluctuations that may occur due to load fluctuations. When the output frequency of the bidirectional inverter is determined according to the rotation speed of the flywheel, the amount of energy stored in the flywheel is maximized to maximize the characteristics of the flywheel function and / or the induction machine, and the stored energy is also stored. Can be effectively utilized.

[Brief description of drawings]

FIG. 1 is a schematic configuration block diagram of an electric power system for explaining an embodiment of an energy storage and emission device using a flywheel according to the present invention.

FIG. 2 is a schematic characteristic diagram of an induction machine for explaining the function of the present invention.

FIG. 3 is an explanatory diagram showing an example of a load fluctuation situation for explaining the function of the present invention.

FIG. 4 is a schematic configuration block diagram showing an example of a conventional power system to which the present invention is applied, where FIG. 4 (A) shows an example of a received power system, and FIG. 4 (B) shows an example of a private power generation system and the like. ing.

[Explanation of symbols]

 1: Power receiving equipment 2: Grid power distribution line 3: Premises distribution line 4: Circuit breaker 5: Power load device 11: Switch 12: Bidirectional inverter 13: Induction machine 14: Flywheel

Claims (2)

[Claims] 1. In a power circuit supplied with electric energy from a power source having a predetermined output capability, an induction machine having a flywheel coupled to the power circuit is connected through a bidirectional inverter, and the power source is provided. Electric power supplied from the bidirectional inverter as a preset frequency or a frequency equal to or higher than a preset frequency of the output frequency of the bidirectional inverter under a power load condition of less than a preset predetermined electric energy corresponding to the output capacity. By operating the induction machine as an electric motor, stored in the flywheel coupled to the induction machine as rotational energy is stored, in the power load conditions above a predetermined electric energy corresponding to the output capacity of the power supply, in the power load conditions, The output frequency of the bidirectional inverter is lower than the preset predetermined frequency. A number of inductors coupled to the flywheel to operate as a generator driven by the flywheel, converting the rotational energy stored in the flywheel into electrical energy and discharging it to the bidirectional inverter. An energy storage and emission device by a flywheel, characterized in that it is consumed in the power circuit via the bidirectional inverter. 2. The output frequency of the bidirectional inverter determined under a power load condition of less than a predetermined electric energy set in advance corresponding to the output capacity of the power source is a predetermined value from the frequency corresponding to the rotation speed of the flywheel. The output frequency of the bidirectional inverter is set higher than the frequency corresponding to the rotation speed of the flywheel, and the output frequency of the bidirectional inverter is set higher than the predetermined frequency corresponding to the output capacity of the power source. The energy storage and emission device according to claim 1, wherein the energy storage and emission device is reduced by a value.