JP3890209B2 - Method and apparatus for inputting rotational speed in governor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a speed governor for a water turbine generator in a hydroelectric power plant, and more particularly to a rotational speed input method and apparatus for the speed governor.
[0002]
[Prior art]
The generator output of the hydroelectric power plant is connected to the power system, and the generators connected in parallel must be synchronized with each other. Therefore, after starting the turbine generator, an operation to synchronize with the frequency of the power system is required. And after connection to an electric power grid | system, it is necessary to synchronize with the other generator connected in parallel. A speed governor is installed for these purposes.
[0003]
FIG. 6 shows a configuration example of the speed control system of the hydroelectric power plant. A deviation 34 between the output 33 of the turbine generator 31 and the signal of the load 32 appears as a change in the rotational speed of the turbine generator. If there is no deviation, the current rotational speed is maintained. The rotation speed signal 1 of the turbine generator detected by the rotation speed detector 35 that outputs a signal proportional to the rotation speed of the turbine generator is taken into the governor 36. The speed control calculation unit 12 calculates a deviation from the rotation speed signal 1 of the turbine generator, the signal of the target speed setting unit 37, and the speed droop rate output signal 38, and then the control target value calculation unit 39 sets the control target value 40. Calculated.
[0004]
On the other hand, the stroke of the servo motor 47 is taken into the speed governor 36 as the servo motor actual opening signal 46. A deviation 41 between the calculated control target value 40 and the servomotor actual opening signal 46 is calculated, and is output to the pressure distribution valve 44 as a control command value 43 through the amplifier 42. An output signal 45 from the pressure distribution valve 44 drives a servo motor 47. The opening of the guide vane is controlled by the operation of the servo motor 47, the amount of water flowing into the turbine is controlled, and the output 33 of the turbine generator 31 is controlled. Accordingly, the rotational speed signal 1 of the turbine generator affects the output 33 of the turbine generator 31.
[0005]
Since the rotational speed signal detection device 35 is normally attached to the turbine generator 31, the shaft runout or vibration of the turbine generator 31 affects the rotational speed signal 1 of the turbine generator.
[0006]
Here, since the shaft vibration frequency is higher than the rotational speed of the water turbine generator, if there is shaft vibration or vibration of the water turbine generator 31, high frequency noise is superimposed on the rotational speed signal 1 of the water turbine generator. Therefore, the rotational speed detection device 35 outputs the rotational speed signal 1 as if the water turbine generator is operated at a rotational speed accompanied by a high-frequency tick.
[0007]
Since the speed governor 36 responds faithfully to the rotational speed signal 1 of the water turbine generator, the control target value calculation unit 39 also outputs a calculation result in response to noise, and the servo motor 47 causes a hunting phenomenon, thereby adjusting the speed. Not only the speed machine 36 but also the life of the water turbine generator 31 and other peripheral devices can be shortened.
[0008]
If the turbine generator rotation speed signal 1 is lost for some reason, such as a malfunction of the rotation speed detector 35, the speed governor 36 determines that the rotation speed of the turbine generator 31 is extremely low and the output is insufficient. Then, in order to increase the rotation speed of the turbine generator and increase the output 33, the servo motor 47 is suddenly opened. Thus, conventionally, a speed governor that does not have countermeasures for the rotation of the rotational speed signal or the loss of the speed signal has been used.
[0009]
[Problems to be solved by the invention]
The above prior art does not consider the possibility of noise being superimposed on the rotation speed signal of the turbine generator, so the speed governor responds to the noise, which may result in damage to the equipment. There are problems such as shortening the service life. There are also the following problems before and after parallel connection to the grid.
[0010]
Before paralleling the power system: There is a risk that the turbine generator rotational speed 1 increases to an unrestrained speed and the turbine and generator are damaged.
[0011]
After paralleling the power system; the turbine generator output 33 suddenly increases, and there is a risk that the generator will burn the generator due to overcurrent.
[0012]
In the above case, the governor control system is an example of hydraulic control, but these problems are the same in a control system that employs an electric servo motor.
[0013]
Furthermore, the same phenomenon occurs when electrical noise enters the rotational speed signal 1 of the water turbine generator input from the rotational speed detection device 35 to the governor 36. Therefore, in order to prevent the intrusion of noise into the rotation speed signal of the turbine generator, measures to increase the rigidity of the rotating part and the fixed part of the turbine generator and greatly increase the natural frequency of the machine part are necessary. is there. In addition, it is necessary to consider the wiring shielding and wiring laying route that can completely prevent the intrusion of noise. However, there are problems that both require a lot of cost and time.
[0014]
The present invention pays attention to the rotational speed signal of the turbine generator, and realizes and provides stable control at low cost without affecting the turbine generator and auxiliary equipment even if the speed signal includes noise. This is to protect the turbine and generator from damage when the rotational speed signal is lost. It is an object of the present invention to provide a rotational speed input method and apparatus in a speed governor in such a case.
[0015]
[Means for Solving the Problems]
The above problem can be solved by the following means.
The rotational speed of the water turbine generator is detected, and a predetermined output signal is selected from a plurality of noise elimination circuits according to the high frequency signal accompanying the shaft vibration of the water turbine generator included in the rotational speed signal. Selecting whether the selected signal is an input signal or a rotation speed signal as a direct input signal according to the operation condition of the water turbine generator, and the selected signal is a rotation speed signal of the governor It can be solved by inputting as.
[0016]
The noise removal circuit is composed of a plurality of first-order lag elements, one output signal of the first-order lag elements is selected as the rotation speed signal, and the selected signal is input to the governor. Further, a primary advance element is provided as a compensation element for the delay element after the primary delay element, and an output signal of the advance element is used as the rotational speed signal. When the loss of the rotation speed signal is detected, the rotation speed signal immediately before is detected and used as a rotation speed signal. When the rotation speed signal is not obtained even after a predetermined time has elapsed, the rotation speed signal is set to a predetermined value. This can be solved by setting a fixed value and shifting to the stop control of the water turbine generator.
[0017]
In a speed governor for controlling the rotational speed of a hydroelectric generator, a plurality of noise removal circuits having a rotational speed signal by a rotational speed detection means of the turbine generator as an input signal, and a magnitude of a high-frequency component included in the rotational speed signal A selection for selecting whether the output signal of the noise removal circuit selected according to the input signal is an input signal or whether the rotational speed signal is directly input to the governor according to the operation condition of the turbine generator It is possible to solve the problem by a rotation speed input device that includes a switching means and that uses the selected and switched signal as an input signal of the governor.
[0018]
Further, the means for detecting the loss of the rotation speed signal, the means for holding the rotation speed signal immediately before the loss of the rotation speed signal is detected by the means, and the time point when the loss of the rotation speed signal is detected. This can be solved by a rotational speed input device that includes a timer that counts the elapsed time and switching means that switches the rotational speed signal to a preset value when a predetermined time has elapsed by the timer.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The rotation speed change period during normal operation of the turbine generator is generally about several tens of seconds. On the other hand, the shaft vibration of the water turbine generator and the noise caused by the vibration are as high as tens of Hz. In the present invention, a noise removal circuit is provided for the rotation signal on which such a noise signal is superimposed, and the output signal is used as a rotation speed signal. Here, a first-order lag element is used as the noise removal circuit. When the frequency of the first-order lag element is equal to or higher than the break point, the gain decreases at 20 db / dec with respect to the input. Therefore, by adding a first-order lag element with a time constant such that the break point of the frequency response characteristic is several Hz, the rotational speed signal can be output with almost no noise caused by shaft vibration or vibration of the turbine generator. Since the speed governor can control only the actual rotational speed of the water turbine generator, stable control can be realized.
[0020]
On the other hand, the phase characteristics of the first-order lag element are delayed before the breakpoint.For example, when controlling the needle when the system is parallel to a Pelton turbine, or when an agile response is required, use the first-order lag element. It may be harmful to driving. For these, if a speed signal selection means capable of selecting use / exclusion of the first-order lag element is provided, it is possible to select a response characteristic required in accordance with the operation. Furthermore, if a primary advance element is provided after the primary delay element and the phase delay of the primary delay element is compensated, control with response characteristics required for operation becomes possible. The output signal of the first-order lag element is selectively used, including inputting the rotational speed signal directly to the governor, depending on the operating condition required for the turbine generator.
[0021]
In addition to the first-order lag element described above, the turbine generator can be protected by adding another second-order lag element having a relatively large delay time. As described above, the speed governor is controlled by the rotational speed signal detected by the rotational speed signal detection device attached to the water turbine generator, but the rotational speed signal may be lost due to some factor. In this case, since the speed governor issues a command to the servo motor to open the guide blade opening more, there is a fear that the rotation of the water turbine generator will rise more than necessary, causing the water turbine generator to be damaged.
[0022]
The second primary delay element follows the rotational speed signal with a certain time constant. Accordingly, the output signal of the second first-order lag element does not immediately disappear even if the input signal is suddenly lost such as the loss of the rotation speed signal. The rotational speed signal 1 input to the governor is constantly monitored, and when the rotational speed signal is lost, the rotational speed signal output to the control target calculation unit of the governor is output from the second primary delay element. Simultaneously with the switching, the output of the second first-order lag element is self-maintained so that the rotational speed signal does not fluctuate. The opening degree by the servo motor can maintain the current value, and the output fluctuation of the turbine generator can be suppressed.
[0023]
The rotational speed signal may contain noise as described in the purpose of installing the first first-order lag element. Since noise is a recoverable incident phenomenon, whether or not it is a recoverable incident phenomenon by setting a confirmation timer so as not to switch to the output of the second primary delay element in response to the noise, that is, It shall be determined whether there is a serious failure that requires the turbine generator to be protected.
[0024]
If the rotation speed signal continues to be lost even after the confirmation timer has elapsed, it is determined that the rotation speed signal cannot be recovered. As a result, the water turbine generator is protected in a safe direction gently (in some cases, immediately).
[0025]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this case, a first-order lag element is used as the noise removal circuit. In FIG. 1, the rotational speed signal 1 detected by the rotational speed signal detector 35 attached to the water turbine generator is taken into the first primary delay element 2. The first primary delay element 2 sets a time constant with a gain K1 so that the break point is several Hz. The first-order lag element has a gain that decreases at 20 db / dec with respect to the input of the frequency above the breakpoint, so it is about several tens of Hz due to shaft vibration, vibration, etc. Since noise is output with a reduced gain, the output signal 13 of the first primary delay element 2 is a rotational speed signal in a state in which high-frequency noise is almost cut.
[0026]
As a result, a rotational speed signal with less noise can be input to the speed control calculation unit 12 and stable control can be performed. The same effect can be obtained by using a circuit (such as a low-pass active filter) that removes high-frequency noise instead of the first primary delay element 2.
[0027]
Since the first primary delay element 2 has a time constant, the output 13 has a time delay. Therefore, when agile responsiveness is required, it is necessary to input the rotational speed signal 1 directly to the speed control calculation unit 12. Therefore, the switching unit 6 switches the rotation speed signal 1 and the output 13 from the first primary delay element 2. Switching between the rotational speed signal 1 and the output signal 13 from the first primary delay element 2 is performed by the rotational speed signal selection means 5.
[0028]
The rotation speed signal selection means 5 is set according to the purpose of operation. For example, when it is desired to make an agile movement before paralleling the power system and to make a stable movement after paralleling the power system, the rotation speed signal selection means 5 may use an ON / OFF signal of a parallel breaker.
[0029]
In addition, if the primary advance element 21 that can set the phase advance at K3 is provided downstream of the first primary delay element 2 as shown in FIG. 5, the time delay of the output 13 can be eliminated.
[0030]
On the other hand, the rotational speed signal 1 is input to the rotational speed signal loss detection unit 4. When it is detected that the rotational speed signal is lost, the output signal 16 is output and input to the timer 9.
[0031]
Since the output 16 may also be output due to noise included in the rotation speed signal 1, if the rotation speed signal loss state set in advance by the timer 9 continues, the rotation speed signal is surely lost. And output 19d. For the second primary delay element 3, a time constant is set by the gain K2.
[0032]
Normally, the output 14 from the second primary delay element 3 is output as an output signal 18 as it is, but when the rotational speed signal is lost, the output signal 18 is self-generated by the output signal 19b from the rotational speed signal loss detection 4. Hold. At the same time, the switching unit 8 switches the output signal 15 from the switching unit 6 to the signal 18. It confirms the output 18 which is a stable and constant signal due to self-holding by the signal 19b, and the signal 18 is output as 17 as the output signal of the switching unit 8.
[0033]
Since the self-holding signal 17 is input to the speed control calculation unit 12, a rapid speed change is not given. Thereby, a sudden change in the servo motor opening can be prevented. Further, if the rotation speed signal is lost for a certain period of time, it is impossible to continue the control any more. Therefore, the output signal 20 is switched to the signal of the set value 11 by the output signal 19d and fixed to the speed control calculation unit 12. The value is input, and the water turbine generator is protected in a safe direction.
[0034]
Next, another embodiment of the present invention will be described. In FIG. 1, 50 can be constituted by a microcomputer (μ-com) or the like. For example, as shown in FIG. 2A, the rotation speed signal 1 is taken in, the signal is processed and judged, and a switching control signal (19a to 19d) is output to perform switching control. FIG. 2B shows a case where a plurality of first-order lag elements are provided in FIG. The first-order lag element 2b is the same as 2 in FIG. 1, but on the basis of this, three temporary delay elements including 2a or 2c are provided, and switching control is performed according to the magnitude of the high-frequency component accompanying shaft vibration or the like. Can do.
[0035]
The signals 13a to 13c are selected according to a predetermined condition. Even when an agile response is required, stable control may be achieved by selecting the signal 13a, for example, rather than inputting the rotation speed signal directly to the speed control calculation unit. Although it depends on the setting of the first-order lag element 2a, even if an agile response is required, the rotational speed signal can be directly input only when the high-frequency component is small.
[0036]
FIG. 3 shows an example of the processing flow. In step 102, the rotational speed signal 1 is captured. In step 104, it is determined whether an agility response is requested. If an agility response is requested, the rotation speed signal 1 is selected in step 112 without going through a first-order lag element. Further, the signal 13a is selected depending on the level of the agile response or the magnitude of the high frequency component. In addition, as shown in step 106, since an agile response is generally required before connection to the system, signal 1 or 13a is selected as the rotation speed signal in step 112. When the high frequency is not superimposed on the rotational speed signal, that is, when the shaft vibration is relatively small, the rotational speed signal 1 is selected, and when the high frequency component is included to some extent, the signal 13a is selected. .
[0037]
In step 108, the rotational speed signal is analyzed to determine the ratios F1 to F3 of the predetermined high frequencies f1 to f3 (f1 <f2 <f3) in the rotational speed signal. In step 110, a signal is selected according to a predetermined condition. For example, when F3 is larger than F1 or F2, since a relatively high frequency signal is included, the signal 13a is selected. Further, when many signals having a relatively low frequency are included, F1 is larger than F2 or F3, and the signal 13c is selected. In this way, an optimal first-order lag element can be selected from a plurality of provided first-order lag elements depending on the magnitude of the high-frequency component.
[0038]
The selection switching signal 19a can be selected as described above. These signal selections correspond to the speed signal selection condition 5 in FIG. When signal 1 is selected, signal 13a is selected when the influence of high frequency is expected. These selection logics may be determined in advance. Various settings such as setting the gain of the first-order lag element 2a to 0.3K1, etc. are conceivable based on K1, and can be determined according to the status of the device.
[0039]
FIG. 4 shows a processing flow corresponding to the speed signal loss detection 4 of FIG. In step 120, it is checked whether or not the rotational speed signal is captured. For example, it is checked whether a predetermined number of pulses are taken in per unit time. If the number of pulses to be input is lost or extremely decreased, it is determined that the rotation speed signal is lost. In step 122, the timer circuit is activated. On the other hand, a signal 19b for switching the first-order lag element 7 to self-holding is output. In step 124, the self-holding is confirmed, and a switching signal 19c is output. This becomes a switching signal of the switching unit 8 in FIG.
[0040]
If a predetermined time has elapsed since the timer was started (rotation speed signal lost time continues for a predetermined time), it is determined that the rotation speed signal has been interrupted for some reason, and a switch 19d to the switching unit 10 is output. The switching signal 19d is switched from the signal 17 to the set value 11. That is, the signal 20 gives a predetermined fixed value (pseudo signal) to the speed control calculation unit 12. In step 127, it is determined whether or not the loss of the rotation speed signal 1 is instantaneous and the timer 9 is restored before a predetermined time has elapsed, and if it is restored, the timer 9 is reset or the self-holding signal 18 is canceled. .
[0041]
FIG. 5 shows an example in which a lead compensation circuit 21 for the first-order lag circuit is provided. In FIG. 2, it is provided in the subsequent stage of 2b. In FIG. 2B, the compensation circuit is often provided at the subsequent stage of 2b and 2c. The temporary delay element 2a is a first-order delay element that does not need to be compensated by the advance circuit, and in many cases, no compensation circuit is provided.
[0042]
As described above, the present invention is to always select the optimal first-order lag element according to the magnitude of the high-frequency component caused by the shaft vibration or the like included in the rotation speed signal. Therefore, the signal input to the speed control calculation unit as the governor rotation speed signal can perform stable speed control without disturbing the control system of the governor. Even when the rotation speed signal is lost, the rotation signal at that time is held by the self-holding circuit and input to the speed control calculation unit to perform speed control, so that the valve opening is not changed abruptly. Further, after the predetermined time has elapsed, the fixed set value is given as a speed signal to the speed control calculation unit 12 and then the control shifts to protection control such as a stop operation of the water turbine generator, so that the control of the governor is not adversely affected.
[0043]
The problem to be solved by the present invention is caused by vibration of the water turbine generator, and it is necessary to fundamentally increase the rigidity of each part. However, it is very expensive. On the other hand, if this phenomenon is left unattended, stable load supply is impossible and the life of the device is shortened. Since the present invention makes it possible to perform stable load operation control only by adding a function to the governor, a cost reduction effect can also be expected.
[0044]
【The invention's effect】
Since the present invention controls the governor based on the signal that has passed through the high-frequency noise signal removal circuit selected according to the magnitude of the high-frequency signal superimposed on the rotational speed signal, the rigidity of the water turbine generator is insufficient. Stable control can be performed even if there is a slight disturbance in the rotational speed signal. Moreover, since it is not necessary to improve the rigidity of the water turbine generator, a reduction in the overall cost can be expected.
[Brief description of the drawings]
FIG. 1 is a block diagram of a rotation speed signal capturing unit and a switching unit in an embodiment of the present invention.
FIG. 2 is a block diagram when switching control is performed by a microcomputer in another embodiment of the present invention.
FIG. 3 shows a microcomputer processing flow chart in FIG. 2;
4 is a flowchart of rotation speed signal loss and timer processing in the microcomputer processing in FIG. 2. FIG.
FIG. 5 is a diagram illustrating an example using a lead compensation circuit.
FIG. 6 is a control block diagram of a conventional general hydroelectric power plant.
[Explanation of symbols]
1; rotational speed signal 2; first primary delay element 3; second primary delay element 4; rotational speed signal loss detection 5; rotational speed signal selection condition 6; switching unit 7; switching unit 8; switching unit 9; 10; switching unit 11; set value 12; speed control calculation unit 13; output 14; output 15; output 16; output 17; output 18; output 19; Load 33; turbine generator output 34; rotational speed 35; rotational speed signal detector 36; governor 37; target speed 38; droop rate output 39; control target value calculation unit 40; control target value 41; deviation 42; Part 43; control command value 44; pressure distribution valve 45; output 46; actual opening 47; servo motor.

Claims (7)

It has a servo motor that operates and controls the guide vane opening to adjust the amount of water flowing into the turbine, and detects the turbine generator's rotational speed in the governor of the hydroelectric power station that controls the rotational speed of the turbine generator. And selecting a predetermined output signal from a plurality of noise elimination circuits according to a high frequency signal accompanying shaft vibration of the turbine generator included in the rotational speed signal, and inputting the selected signal. Whether to use a signal or a rotation speed signal as a direct input signal is selected according to the operation condition of the water turbine generator, and the selected signal is input as a rotation speed signal of the governor. A rotational speed input method for a governor. 2. The noise removal circuit according to claim 1, wherein the noise removal circuit includes a plurality of first-order lag elements, selects one output signal of the first-order lag elements as the rotation speed signal, and inputs the selected signal to the governor. A rotational speed input method for a speed governor. The rotational speed input in the governor according to claim 2, wherein a primary advance element is provided as a compensation element for the delay element after the primary delay element, and an output signal of the advance element is used as the rotational speed signal. Method. 2. The rotation speed signal according to claim 1, wherein when the loss of the rotation speed signal is detected, the rotation speed signal immediately before being held is used as a rotation speed signal, and the rotation speed signal cannot be obtained even after a predetermined time has elapsed. Is set to a predetermined fixed value, and the process proceeds to stop control of the turbine generator. A servo motor that controls the opening degree of the guide vane that adjusts the amount of water flowing into the water turbine, a rotational speed detection means of the water turbine generator, and a target speed setting unit, and controls the rotational speed of the hydraulic power generator A plurality of noise removal circuits having a rotation speed signal from the rotation speed detection means of the water turbine generator as an input signal, and the noise removal circuit selected according to the magnitude of the high frequency component included in the rotation speed signal Selection switching means for selecting according to the operation conditions of the turbine generator whether to use the output signal of the turbine as an input signal or the rotational speed signal as an input signal directly to the governor. A rotational speed input device in a speed governor, wherein a signal is an input signal of the speed governor. 6. The means for detecting the loss of the rotation speed signal, the means for holding the rotation speed signal immediately before the loss of the rotation speed signal is detected by the means, and the loss of the rotation speed signal are detected. And a switching means for switching the rotation speed signal to a predetermined set value when a predetermined time has elapsed by the timer, and the rotation in the governor Speed input device. 6. The rotational speed input in the governor according to claim 5, wherein the plurality of noise elimination circuits are configured with a first-order lag element, and a compensation circuit for compensating for a delay is provided at a subsequent stage of the first-order lag element. apparatus.

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