JPH119000A - Control method for variable speed motor, and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the functions to stabilize a power system, which prevents an essential generator or a group of generators from dropping from the system by the fluctuation, and besides stabilizes the fluctuation in case that the fluctuation occurs in the power of the power system, with a minimum capacity of the variable speed generator. SOLUTION: The control block of the case where a variable speed generator generates power is equipped with a control circuit 15 for stabilization and a rotational speed compensation control circuit 16, and waiting operation is performed in the vicinity of the lower limit or the upper limit of the variable speed range of the rotational speed of the variable speed generator 3, and also the active power is discharged from or absorbed into the variable generator 3, according to the direction of the power of the group of generators which are the target of stabilization when abnormality occurs in the power system 1, thus the system is stabilized, making use of the variable speed range to the utmost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable-speed generator, and more particularly to a variable-speed generator which is connected to an AC power system and immediately releases or absorbs active power when an abnormality occurs in the system.
The present invention relates to a control method and a control device for a variable-speed generator capable of improving system stability.

[0002]

2. Description of the Related Art Conventionally, as one of control methods for controlling the active power of a variable-speed generator at high speed and using it for stabilization control of a power system, Japanese Patent Application No. 5-219507, "Operation of Variable-Speed Generator" There is a technology disclosed in the Law.

According to this, in the power system to which the generator is connected, the output of the variable speed generator is adjusted so as to suppress power fluctuation of the transmission line, thereby realizing the stabilization of the power system. It is possible.

For example, in a two-line power transmission system, when a ground fault occurs on one line, the power on the load side is insufficient due to the interruption of one line on the ground fault side, and the system voltage is thereby reduced. I do. In particular, when the required power is constant on the load side, the transmission current increases due to the voltage drop, the voltage drop of the transmission line becomes larger, and the voltage drop on the load side increases. In such a case, it is possible to adjust the output of the variable speed generator connected to the load side, temporarily increase the load side voltage, and suppress the voltage drop of the transmission line.

According to the above prior art, the phenomenon is grasped based on the information on the phenomenon at the time of ground fault, the fluctuation and the operating state of the circuit breaker, and the active power of the variable speed synchronous machine is controlled at a high speed, so that the power system can be controlled. Stabilization can be achieved.

[0006]

However, as described above, a technique for controlling the active power of a variable-speed machine at the time of a system abnormality has been proposed. However, the technique depends on the generator group to be stabilized and the power flow direction of the system. The control method and the standby rotation speed control of the variable speed generator are not mentioned in the above-mentioned conventional technology.

In particular, when the amount of active power that can be controlled by the variable speed generator is small compared to the capacity of the group of generators, there is a problem in how to maximize the active power control capability of the variable speed generator. .

According to the present invention, when any disturbance occurs in the power system and the power of the power system fluctuates, the fluctuation prevents an important generator and a group of generators from dropping out of the system, and The present invention relates to a control method for stabilizing the fluctuation, and aims to provide a function of stabilizing an electric power system with a minimum capacity of a variable speed generator.

[0009]

To achieve the above object, the present invention provides a primary winding connected to a point located between a power system and a generator or a group of generators connected to the power system. And a variable-speed generator control device having a secondary winding, wherein the power is supplied from the power system via a transformer, and the output side is connected to the secondary winding of the variable-speed generator to supply an alternating current having a variable frequency. A power conversion unit, a current control system that controls an alternating current supplied by the power conversion unit, a voltage control system and a power control system that input a variable value for setting a control target in the current control system, Abnormality detection means for detecting an abnormality of the power system, and power detection means for detecting active power other than the point where the variable speed generator is connected, the power control system, the abnormality detection means Anomalies in the power system Is detected, comprises a stabilization control means for performing active power control of the variable speed generator, the stabilization control means, when performing the active power control, the power detection means detected The sign of the amount of the active power of the variable speed generator to be corrected is switched according to the direction of the power flow.

According to another aspect of the present invention, there is provided a method for controlling a variable speed generator, the method comprising the step of connecting the variable speed generator when an abnormality occurs in the power system. The direction of the active power flow is detected, the sign of the amount of active power to be corrected is switched according to the direction of the active power flow, and the active power control of the variable speed generator is performed using the correction amount obtained as a result. .

[0011]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, for example, a variable-speed generator is installed between a generator or a group of generators to be stabilized and a load, and a voltage at a point where the variable-speed generator is connected is set. While detecting current, active power, and reactive power, detecting active power in the vicinity of a generator or group of generators to be stabilized, and controlling the operating rotational speed of the variable speed generator according to the direction of the active power. And a function for determining the active power control code at the time of an accident.

That is, in the steady state, when the active power of the generator or group of generators to be stabilized is directed to the load side, the rotation speed of the variable speed generator is set near the lower limit of the variable speed range, When the direction of the active power of the generator group is directed to the generator side, speed control is performed so that the rotation speed of the variable speed generator is operated near the upper limit of the variable speed range.

Further, in the event of a system failure, if the direction of the active power of the generator or generator group to be stabilized is directed toward the load, the active power control of the variable speed generator is controlled to the power absorbing side. This suppresses the acceleration of the generator to be stabilized, and when the active power of the generator group is facing the generator side, the active power control of the variable speed generator is set to the power release side. The control prevents the generator to be stabilized from decelerating and dropping out of the grid.

Hereinafter, a control system including a variable speed generator to which an embodiment of the control method of the present invention is applied will be described in more detail with reference to FIGS. FIG. 1 shows a configuration example of a control block when a variable speed generator included in the present system performs a power generation operation.

In this system, as shown in FIG. 1, a variable-speed generator 3 connected to a power system 1 via a main transformer 2 includes a power converter 4 such as a cycloconverter.
Is excited by AC. The power conversion device 4 includes the power system 1
Is connected via an exciting transformer 5 to change the phase of the AC exciting current to increase or decrease the output of the variable speed generator 3.

The system further includes a voltage controller 7, a power controller 8, a current controller 9, a pulse phase shifter 10, a speed detector 11, a speed controller 12, Motor 13 and pump turbine 14
And a stabilization control circuit 15 and a rotational speed correction control circuit 16 which are characteristic configurations of the present invention.

The voltage controller 7 includes a voltage V of the power system 1 detected by the power detector 6 and a voltage command V
Adjust so that the deviation of ref becomes zero. This voltage controller 7 is a component of the secondary current of the variable-speed generator 3 that has a phase different from the voltage phase of the AC power system 1 by π / 2 in electrical angle when viewed from the primary side (abbreviated as a d-axis component). ) Which generates the command value.

The power controller 8 adjusts the difference between the active power P supplied from the power system 1 detected by the power detector 6 and the active power command Pref given from the outside to zero. The power controller 8 is a device that generates a command value of a component (abbreviated as a q-axis component) of the secondary current of the variable speed generator 3 that is equal to the voltage phase of the power system 1 when viewed from the primary side. .

The current controller 9 calculates secondary-side phase current commands Ia *, Ib *, Ic * from the d-axis component current and the q-axis component current, and calculates the current command value and the output current of the power converter 4. The detected values Ima, Imb, Imc are compared, and the power converter 4 is controlled so that the deviation becomes zero. The pulse phase shifter 10 generates a gate pulse to be supplied to the elements constituting the power converter 4.

The speed controller 12 controls the rotation speed N of the variable speed generator 3 detected by the speed detector 11 and the rotation speed command Nr.
Adjust so that the deviation of ef becomes zero.

The pump turbine 14 has an optimum rotation speed Nref.
The servo motor 13 is controlled by the output of the speed controller 12 and the value of the optimum guide vane opening command Yref, and the guide vane opening is determined. By controlling in this way, it is possible to control the active power output by the Iq command and the generator voltage or the reactive power by the Id command while maintaining an appropriate rotation speed.

The stabilization control circuit 15 includes, for example, a system fault signal transmitted based on the open / closed state of the circuit breaker and a power detector 18 (FIG. 2) provided near a synchronous machine other than the variable speed generator. Active power signal PL detected by
And outputs a stabilizing signal (active power correction signal) ΔPss for correcting the active power command when a system fault occurs.

The rotation speed correction control circuit 16 outputs a correction signal ΔN for a rotation speed command in a steady state from an active power signal PL near a synchronous machine other than the variable speed generator.

In the system of the present embodiment, as shown in FIG. 2, a synchronous machine or a group of synchronous machines 20 is connected to the system on the load side 30, and the variable speed generator 3 is installed therebetween. . Further, a power detector 6 is provided near the variable speed generator 3 to detect the output power PG from the variable speed generator 3, and a power detector 18 is provided near the synchronous machine 20 to The nearby active power PL is detected.

Now, assuming that a ground fault has occurred in one of the two circuits 32 and a high-speed re-closing (accidental phase breaker 34 cut-off → re-closing) is performed, the synchronous machine 20 performs power generation operation. In this case, the impedance of the systems 33 and 34 during the open phase increases, and the amount of power that can be transmitted to the load 30 decreases. For this reason, the synchronous machine 20 accelerates, and at the time of high-speed reclosing, the voltage phase on the synchronous machine 20 side advances from the voltage phase on the load side 30, the phase is switched on, the power fluctuation continues, and the worst synchronous machine Step out and you will fall out of the grid.

At this time, the variable speed generator 3 detects its own output power PG, and also detects a system fault signal such as a circuit breaker operation and the sign of the detected active power PL (flow direction).
From the detected information, and control is performed so as to temporarily absorb the active power of the variable speed generator 3. For example, when the variable-speed generator 3 performs a power generation operation, control is performed so as to reduce the power generation output.

A specific configuration example and operation of the stabilization control circuit 15 of FIG. 1 for realizing the above control operation will be described with reference to FIG.

The stabilization control circuit 15 of this embodiment includes a correction signal generator 151 for generating an active power correction signal ΔPss, comparators 152, setting sections 153 and 154 for setting values of Ps, and a comparison result of the comparator 152. And a selection unit 155 for switching a setting unit to be connected according to the setting. The stabilization control circuit 15 can be realized by, for example, software expressing a functional algorithm of each unit described above. Here, the comparator 152 compares a predetermined threshold value (0 in this example) with an input value, and each variable is defined as follows.

Ps: magnitude of active power command to be corrected from time t1 to t2 Po: amount to correct active power (correction amount) t1: correction start time t2: time to correct active power by Po or -Po The time t1 is set, for example, according to the operation timing of a circuit breaker that operates to open (eliminate) a system fault phase when a system fault occurs, and the time t2 is continuously corrected to the time t1. It is set in advance according to the length of the period to be performed.

In the stabilization control circuit 15 of this embodiment, the comparator 152 which determines the sign of the input PL signal determines whether the PL is negative (the power flow direction near the synchronous machine 20 is the power generation operation direction) or the PL signal is low. It is determined whether it is correct (the synchronous machine 20 is in the pumping operation direction). When the PL signal is negative, the sign of the active power correction signal for stabilization, which is output using the system fault signal as a trigger, is positive (in the direction in which the variable speed generator absorbs active power). When the PL signal is positive (the power flow direction near the synchronous machine 20 is the pumping operation direction), the sign of the active power correction signal is negative (the direction in which the variable speed generator emits active power).

According to the above configuration, in the control of the active power at the occurrence of a system fault, if the detected value of the active power PL is negative, the variable speed generator 3 absorbs the active power, It is possible to prevent the active power of the synchronous machine 20 from being excessive during the phase loss and being accelerated. When the value of the detected active power PL is positive, the variable-speed generator 3 emits active power to prevent the input power of the synchronous machine 20 from decreasing and decelerating during phase loss. it can.

Next, the rotation speed correction control circuit 1 shown in FIG.
6 will be described with reference to FIG.

In the system having the above-mentioned stabilization control circuit 15, the rotational energy of the variable speed generator 3 is converted into electric power and absorbed / discharged. Therefore, in order to more efficiently transfer and receive large energy, it is necessary to increase the inertia moment of the rotor of the variable speed machine 3 or the speed change range. An increase in the moment of inertia increases the size of the variable speed machine 3, and an increase in the speed change range leads to an increase in the secondary voltage of the variable speed generator, thereby enlarging the power converter 4.
However, if the widest possible range of speed change can be used, the maximum power absorption and emission can be achieved without changing the size of the device.

In order to realize such control, the rotation speed correction control circuit 16 of this embodiment includes a comparator 161 for determining the sign of the active power PL, and setting units 162 and 163 for setting the value of the rotation speed correction signal ΔN. And a selection unit 16 for switching a setting unit to be connected according to the comparison result of the comparator 161
4 is provided. The rotation speed correction control circuit 16 can be realized by, for example, software that expresses a function algorithm of each unit described above. Here, the variable N is a rotation speed correction amount.

In the rotation speed correction control circuit 16 of this embodiment, a comparator 161 for determining the sign of the active power PL near the synchronous machine 20 is provided, and the active power PL is negative (the power flow direction near the synchronous machine 20 is Direction) or whether the active power PL is positive (the synchronous machine 20 is in the pumping operation direction). Active power PL
Is negative, the rotation speed command correction signal ΔN is made negative,
When the active power PL is positive (the power flow direction near the synchronous machine 20 is the pumping operation direction), ΔN is set to be positive.

According to the above configuration, in the control of the rotation speed, when the active power PL is negative, the rotation speed of the variable speed generator 3 in the steady state becomes a lower speed side than normal operation, Even if the variable speed generator 3 absorbs power and the rotation speed increases, it is difficult to deviate from the variable speed range. Also,
When the active power PL is positive, the rotation speed of the variable speed generator 3 in the steady state is higher than normal operation, and it is possible even if the rotation speed is reduced by the variable speed generator 3 releasing power. It is difficult to deviate from the shift range.

Next, another embodiment of the present invention will be described with reference to FIG. In the following description and FIG.
The same reference numerals are given to the same configurations as those of the embodiment, and the detailed description thereof will be omitted.

The system of the present embodiment comprises a variable speed generator 3
Is suitable for pumping operation or phase operation,
It has a control block configuration as shown in FIG. In the pumping and phase adjustment modes of the present embodiment, the speed control is performed by adding the output of the speed controller 12 output to the servo motor 13 in the embodiment of FIG. 1 to the active power command Pref.

In the case of the phase adjusting operation, the servo motor 13 closes the guide vane opening to zero, sets the active power command Pref to zero, and operates the pump turbine 14 in a state where the water surface is pushed down. Also in this case, the stabilization control circuit 15 is installed, and the sign of the active power correction signal ΔPss for stabilization is switched according to the sign of the PL of the synchronous machine 20, so that the synchronous machine 20 loses synchronism at the time of a system failure. Can be prevented. Further, by further providing the rotation speed correction control circuit 16, the amount of power that can be absorbed / released by the variable speed generator 3 can be maximized.

In the case of pumping, since the rotation speed is closely related to the input active power of the variable speed generator 3, it may not always be appropriate to correct the rotation speed as described above. In the case of the phase adjustment operation, there is little restriction on the set rotation speed, and the above operation is particularly effective.

[0041]

According to the present invention, the stabilization and release of the active power can be performed so as to suppress the fluctuation of the power of other generators and the drop out of the system when the system is abnormal. large.

Further, according to the present invention, the amount of electric power to be discharged and absorbed can be used to the maximum without changing the variable speed range, and the size of the system can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall control block diagram when a variable-speed generator performs a power generation operation in one embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an operation of the entire system in the embodiment of FIG. 1;

FIG. 3 is a block diagram showing a configuration example of a stabilization control circuit of the present invention.

FIG. 4 is a block diagram illustrating a configuration example of a rotation speed correction control circuit according to the present invention.

FIG. 5 is an overall control block diagram of another embodiment of the present invention when a variable speed generator is pumped or operated in phase.

[Explanation of symbols]

1. . . Power system, 2. . . 2. main transformer; . . 3. Variable speed generator, . . Power converter, 5. . . Exciting transformer,
6. . . Power detector, 7. . . Voltage controller, 8. . . Power controller, 9. . . Current control system, 10. . . 10. pulse phaser; . . Speed detector, 12. . . Speed controller, 1
3. . . 13. servo motor, . . Pump turbine 1
5. . . 15. stabilization control circuit; . . Rotating speed correction control circuit, 20. . . Synchronous machine, 30. . . Load system, 31,
32. . . Transmission line impedance, 33, 34. . . Circuit breaker.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Motoo Futami 7-2-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Power and Electricity Development Division (72) Inventor Nobuhiro Takahashi Higashi-ku, Nagoya-shi, Aichi Prefecture 1 Higashishinmachi Chubu Electric Power Co., Inc.

Claims (8)

[Claims] 1. A power supply connected to a point located between a power system and a generator or a group of generators connected to the power system,
In a control device for a variable speed generator having a primary winding and a secondary winding, power is supplied from the power system via a transformer, and an output side is connected to a secondary winding of the variable speed generator, and an AC of variable frequency is connected. A power conversion unit that supplies current, a current control system that controls an alternating current supplied by the power conversion unit, a voltage control system that inputs a variable value for setting a control target in the current control system, and power control. System, an abnormality detection unit for detecting an abnormality of the power system, and a power detection unit for detecting an active power other than a point to which the variable speed generator is connected. Means for performing active power control of the variable speed generator when the occurrence of an abnormality in the power system is detected by the means, wherein the stabilization control means performs the active power control. At the time, A control device for a variable speed generator, wherein a sign of an amount to be corrected for the active power of the variable speed generator is switched according to a direction of a power flow detected by a force detection unit. 2. The stabilization control unit according to claim 1, wherein the stabilization control unit determines whether the sign of the active power value detected by the power detection unit is positive or negative in order to specify the direction of the power flow. First setting means for setting an amount to be corrected when the sign of the active power is positive; second setting means for setting an amount to be corrected when the sign of the active power is negative; The selection means for selecting one of the two setting means in accordance with the determination result of the above, and the setting means selected by the selection means in response to the occurrence of the abnormality detected by the abnormality detection means Amount, a correction signal generating means for generating an active power correction signal for controlling to correct for a specific period, the power control system, the active power value in the variable speed generator, from the outside, Power command value to be input, A variable speed generator control device, wherein active power control of the variable speed generator is performed in accordance with a correction amount indicated by the active power correction signal. 3. The power control system according to claim 1, further comprising a speed control system for controlling a rotation speed of the variable speed generator, wherein the speed control system is configured to: Variable speed control means for switching a sign of an amount to be corrected of the rotation speed of the variable speed generator and controlling the rotation speed so as to change by a correction amount obtained as a result. Generator control device. 4. The rotation speed correction unit according to claim 3, wherein the rotation speed correction unit determines whether the sign of the active power value detected by the power detection unit is positive or negative to specify the direction of the power flow, First setting means for setting an amount to be corrected when the sign of the active power is positive; second setting means for setting an amount to be corrected when the sign of the active power is negative; Selecting means for selecting one of the two setting means according to the determination result of the above. The speed control system comprises: a rotation speed of the variable speed generator; and a power command value input from the outside. A control device for a variable speed generator, wherein the rotation speed control is performed in accordance with a correction amount indicated by a setting unit selected by a selection unit of the rotation speed correction unit. 5. The control system according to claim 3, further comprising a control mode in which said variable speed generator performs a phase adjustment operation, wherein said power control system stabilizes a control output of said speed control system in said control mode. A control device for a variable speed generator, wherein active power control is performed according to a result added to a control output of a control means and an active power value of the variable speed generator. 6. A method of controlling a variable speed generator connected to a point located between a power system and a generator or a group of generators connected to the power system, wherein an abnormality occurs in the power system. The direction of the active power flow other than the point where the variable speed generator is connected is detected, and the sign of the amount to be corrected for the active power is switched in accordance with the direction of the power flow, and the correction obtained as a result is obtained. A method for controlling a variable speed generator, wherein active power control of the variable speed generator is performed using a quantity. 7. The power flow direction according to claim 6, wherein when no abnormality occurs in the power system, the direction of the active power flow other than the point where the variable speed generator is connected is detected. Switching the sign of the amount to be corrected of the rotational speed of the variable speed generator in accordance with the variable speed generator, and performing the rotational speed control of the variable speed generator using the correction amount obtained as a result. Generator control method. 8. A control mode according to claim 7, further comprising a control mode in which said variable speed generator performs a phase adjustment operation. In said control mode, said control output of said rotational speed is controlled by said active power control output when said abnormality occurs. A variable speed generator control device which performs active power control of the variable speed generator in accordance with an output obtained as a result thereof and an active power value of the variable speed generator.