JPH05153800A - Variable speed pumped-storage hydroelectric generator system - Google Patents

Abstract

PURPOSE:To operate even if a partial circuit of a secondary exciter is defective and to suppress generation of an overvoltage when a system accident occurs and/or an exciting converter is defective. CONSTITUTION:An exciting converter 6 of one group of a polyphase, or multigroup type structure is disconnected from an exciter at the time of a system trouble, the exciter is subsequently operated by an exciting converter 6 of the other group. A DC circuit is short-circuited by turning ON a gate of a thyristor of an inverter 12 at the time of a system trouble, and an overvoltage is suppressed. Further, the DC circuit is short-circuited by a protective GTO thyristor and the inverter 12 even at the time of a trouble of the converter 6, and a failure of an apparatus due to the overvoltage is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed pumped storage power generation system for operating an AC excitation synchronous machine under the control of an excitation converter.

[0002]

2. Description of the Related Art FIG. 7 is a circuit diagram showing a conventional variable speed pumping system, in which 1 is an armature of an AC excitation synchronous machine (hereinafter referred to as AESM) 50 and 2 is an AESM 50.
With a secondary coil, 3 is a reversible pump turbine directly connected to the rotor 2, 4 is a shaft, 5 is a transformer for an excitation converter, and 6 is a thyristor drive circuit for controlling the excitation current of the secondary coil. An excitation converter (hereinafter referred to as EX), 7 is an EX6 controller.

Next, the operation will be described. AESM50
In order to operate at a variable speed, the method of secondary excitation of AESM50 is usually adopted, and if the frequency is corrected by the secondary excitation by the slip amount so that it matches the system frequency even if the rotation speed changes, Parallel operation is possible.

Further, in EX6, a cycloconverter system for directly producing an alternating current from an alternating current or a system composed of an inverter and a converter for once converting to a direct current is used.
The AESM 50 is operated so that the electric power taken in by the EX 6 via the exciter transformer 5 becomes the electric power and the optimum rotation speed set under the ignition control by the controller 7.

FIG. 8 is a circuit diagram showing another conventional variable speed pumping system. The same or corresponding parts as those in FIG. 7 are designated by the same reference numerals and their duplicate description will be omitted.
In FIG. 8, 8 is an overvoltage suppressing thyristor circuit for suppressing an overvoltage of the output voltage of the EX6, 9 is an overvoltage suppressing arrester for the output voltage, and 10 is an overvoltage detecting circuit.

In this conventional example, in order to operate the AESM 50 at a variable speed, a method of secondary excitation of the AESM 50 is usually adopted, and even if the rotation speed changes, the secondary excitation is performed by a slip amount so as to match the system frequency. By correcting the frequency with, parallel operation with the system is enabled.

Further, in EX6, a cycloconverter system for directly making alternating current from alternating current is used, and when a system fault occurs, an overvoltage occurs in the secondary coil of the AESM50,
The overvoltage is detected by the overvoltage detection circuit 10, and the thyristor of the overvoltage suppressing thyristor circuit 8 is ignited according to the detection result to suppress the overvoltage.

[0008]

Since the conventional variable speed pumped storage hydropower system is configured as described above, the system of FIG. 7 includes the thyristor and the like because the EX6 has a multi-phase one-group configuration. There is a problem in that the operation of the AESM 50 cannot be continued due to a failure of some of the converter elements, that is, the failure of one element causes loss of the excitation capability, and the AESM 50 must be stopped continuously. ..

Further, in the system of FIG. 8, it is necessary to provide an overvoltage protection device such as an overvoltage suppressing thyristor circuit 8 and an overvoltage suppressing arrester 9 on the output side of the EX6.
As a result, the circuit configuration becomes complicated, and the space occupied by each part of these circuits becomes large, which is uneconomical.

Further, in the system shown in FIG. 8, although the system side accident can be dealt with, the EX6 cannot be protected, the structure is complicated and the occupying space of each circuit element becomes large, which is uneconomical. There was a problem. A technique similar to such a conventional variable speed pumped storage power generation system is described in 1991 National Meeting of the Institute of Electrical Engineers, pp. 1066, 9-59-60 and 1070, 8-247-248.

The invention of claim 1 is to solve the above-mentioned problems, and by devising the circuit system of the EX, even if a converter element in a part of the EX fails, it continues. It is an object of the present invention to obtain a variable speed pumped storage power generation system that can realize the operation of AESM.

It is another object of the present invention to provide a variable speed pumped storage power generation system capable of taking measures against overvoltage with a relatively simple and small circuit structure.

A third object of the present invention is to provide a variable speed pumped storage hydropower system capable of simply responding to a system-side accident and protecting the excitation converter from failure.

[0014]

The variable speed pumped storage hydropower system according to the invention of claim 1 separates the EX of the failed group from the secondary side among the EXs in the multi-phase multi-group form and leaves the other EXs. An inverter control circuit is provided to enable the secondary side to be excited by a normal group of excitation transducers.

Further, the variable speed pumped storage hydropower system according to claim 2 is provided with a converter that constitutes an EX and an inverter that converts a system voltage into a direct current, an inverter that converts an output of the converter into an alternating current, and an input side of the inverter. And an inverter control circuit based on the output of the overvoltage detection circuit, the gate of the inverter is turned off in the event of a system fault to suppress the overvoltage, and the gate of the inverter is recovered after the system fault is recovered. Off, turn on the converter gate to restore normal operation, while
If the system accident is not recovered, the unit is tripped.

Further, the variable speed pumped storage hydropower system according to the invention of claim 3 constitutes an EX, a converter for converting the system voltage into a DC, an inverter for converting the output of the converter into an AC, and an input side of the inverter. An overvoltage detection circuit and a protective gate turn-off thyristor provided in the inverter control circuit are provided to the inverter control circuit when an overcurrent on the output side of the inverter is detected or when an overvoltage is detected by the overvoltage detection circuit. To short-circuit the output circuit of the converter or / and to simultaneously ignite all the thyristors of all bridges in the inverter to short-circuit the secondary circuit, and after the accident recovery, restore the inverter and the converter to normal operation. On the other hand, if the accident does not recover, unit trip It is intended.

[0017]

In the inverter control circuit according to the first aspect of the present invention, when one group of EXs having a multi-group structure fails, the AESMs can be continuously operated by the remaining EXs.
The EX control is also controlled by the remaining group, and power generation is controlled within the power range in which the remaining group can operate.

In the inverter control circuit according to the second aspect of the present invention, the overvoltage detection circuit detects the overvoltage of the DC circuit on the converter output side, and when this is detected, the inverters are simultaneously fired to short-circuit the secondary side of the AESM. And suppress temporary overvoltage until the accident recovery.

The inverter control circuit according to the third aspect of the present invention detects overvoltage and overcurrent of the DC circuit on the converter output side at the time of a system side accident and at the time of EX failure, and according to the detection result, the protective gate turn-off thyristor. Is activated to short-circuit the DC circuit or to simultaneously ignite the gate turn-off inverters to short-circuit the secondary side of the AESM.
Prevent overcurrent.

[0020]

EXAMPLES Example 1. An embodiment of the invention of claim 1 will be described below with reference to the drawings. In FIG. 1, 1 is AES
M50 armature, 2 rotor with secondary coil of AESM50, 3 reversible pump turbine directly connected to rotor 2, 4 shaft, 5 EX converter, 11 converter constituting EX6 , 12 is an inverter constituting the EX6, 13 is a DC link capacitor, 14 is an inverter 1
A disconnector provided on the output side of 2 and a converter 11
A disconnector provided on the input side of the inverter 16 is an inverter control circuit. Further, the EX 6 including the inverter 12 and the converter 11 has a system configuration in which three groups are provided.

Next, the operation will be described. First, the inverter control circuit 16 is controlled so that the commanded power, reactive power, voltage, and optimum rotation speed are achieved. On the other hand, independently of this, the converter output voltage and the conversion power factor of the EX6 are set to 1.0. The converter 11 is controlled to do so. Further, in the present invention, the EX6 is divided into other groups (here, three groups) in order to increase the capacity, so that it is necessary to control the current balance between the respective EX6 groups.

When, for example, the upper group EX6 among the above-mentioned three groups of EX6 fails, the disconnectors 14 and 15 on the output side and the input side of this upper group EX6 are opened, and the remaining middle group. And AESM50 is excited by EX6 of the lower group. Then, in the EX6 of the second group, the inverter control circuit 16 controls the inverter 12 so that the commanded power, reactive power, voltage, and optimum speed of the allowable range are achieved, thereby enabling continuous operation of the AESM 50. .. This operation can be applied to both power generation operation and pumping operation.

Example 2. In the above embodiment, the forced commutation type multi-phase multi-group gate turn-off (hereinafter referred to as GTO) type constituted by the inverter 12 and the converter 11 as the EX6 has been described, but a cycloconverter type may be used and the number of phases may be changed. If the number of groups is 3 or more and the number of groups is 2 or more, the same effect as that of the above-described embodiment can be obtained.

In this case, the concept of multi-grouping is also based on the method of partial load operation at the time of failure of one group, or the converter multi-group configuration with one group margin so that normal operation is performed even after disconnecting the failure group in the case of one group failure. It is also possible to make it possible.

[0025] Moreover, it is not limited to pumped storage power plants
The same effect can be obtained by using M in an applied plant such as a flicker prevention system using a flywheel generator.

Example 3. Next, an embodiment of the invention of claim 2 will be described with reference to the drawings. In FIG. 2, 1 is AE
SM armature, 2 rotor with secondary coil, 3 reversible pump turbine, 4 shaft, 5 EX converter,
These are the same or equivalent components as shown in FIG. Further, 6 is an EX, which is the converter 11, the inverter 12, the overvoltage detection circuit 25 and the DC link capacitor 1 placed in the DC circuit on the output side of the converter 11.
7 and 7. Reference numeral 18 denotes an inverter control circuit for controlling simultaneous firing of all bridge GTO thyristors in the inverter 12 when the DC circuit is overvoltage.

Further, FIG. 3 shows the inverter 12 in FIG.
FIG. 3 is a circuit diagram specifically showing that GTO thyristors S1 to S6 placed in each bridge are connected to diodes D1 to D1.
2, and normally, direct current is sequentially transferred to each of the thyristors S1 to S6 to be converted into alternating current power, which can be supplied to the secondary coil 2.

Next, the operation will be described. Now, if an accident such as a one-wire ground fault, a two-wire ground fault, or a short circuit occurs on the system side, an overvoltage occurs in the secondary coil 2 of the AESM 50. At this time, in order to prevent damage to the device, the overvoltage detection circuit 25 detects this and outputs it to the inverter control circuit 18, and all GTO thyristors S1 to S6 of all bridges constituting the inverter 12 are simultaneously ignited.

Therefore, the secondary circuit at this time short-circuits the secondary circuit as shown by the dotted arrow in FIG. 3, for example, for an instant, so that the AESM 50 operates as an induction machine.
Overvoltage is suppressed. At this time, the gate of the converter 11 is turned off and the operation of the converter 11 is stopped.

On the other hand, if the fault on the system side is eliminated by the operation of the breaker of the power transmission line, the inverter 12 is gated off by the inverter control circuit 18, and then both the converter 11 and the inverter 12 are normally fired. Then, the operation of the AESM50 is continued. In this case, if the system accident continues after a certain time, the whole unit will be stopped.

Example 4. It should be noted that although the forced commutation type 12-phase voltage inverter 12 is used as the EX 6 in the above embodiment, it may be a multi-phase type other than 12-phase, and the converter 11 is not limited to the GTO type. It is not necessary and can be applied to an application product of the AESM50, such as a flywheel generator or a frequency converter, instead of the variable speed pumping machine, and the same effect as that of the above-described embodiment is obtained.

Example 5. FIG. 4 is a circuit diagram showing an embodiment of the invention of claim 3, in which 11 is an EX6 converter, 12 is an EX6 inverter, 19 is an inverter control circuit for controlling firing of a thyristor of the inverter 12, and 17 Is a DC link capacitor inserted in the DC circuit on the converter output side, 25 is an overvoltage detection circuit, and the set voltage is set higher than that of the overvoltage detection circuit 10 provided separately. 22 is a protective GTO thyristor which is controlled by the output of the overvoltage detection circuit 10; 23 is a short-circuit resistor;
These are connected in series with each other and in parallel with the DC link capacitor 17. 20 is a converter 2 for detecting the secondary current of the AESM 50 on the output side of the inverter 12.
1 is an overcurrent detection circuit that is connected via 1 to detect an overcurrent and inputs this detection signal to the inverter control circuit 19.

FIG. 5 is a circuit diagram showing the details of the inverter 12, which has the GTO thyristors S1 to S6 put in the respective bridges together with the diodes D1 to D12. Is converted to AC power and can be supplied to the secondary coil 2.

Next, the operation will be described with reference to the flowchart of FIG. Now, if an accident such as a one-line ground fault, a two-line ground fault, or a short circuit occurs on the system side,
Overvoltage or overcurrent occurs on the secondary side of the AESM 50. Further, the voltage of the DC circuit between the converter 11 and the inverter 12 also rises due to the failure of the EX6, resulting in an overvoltage.

Therefore, in order to prevent the equipment from being damaged due to such abnormalities in voltage and current, this overvoltage is detected by the overvoltage detection circuit 10 at the output side of the converter 11, and the protection GTO thyristor 22 is ignited by this detection signal. (Step ST1), each DC link capacitor 17 is short-circuited through the short-circuit resistor 23.

Next, it is judged whether or not the DC voltage on the output side of the converter 11 has become lower than a predetermined low set level of the overvoltage detection circuit 10 due to this short circuit (step ST
2) If the following occurs, the protective GTO thyristor is gated off (step ST3).

At this time, if it does not fall below the low set level, it is judged whether or not the AESM voltage has normally recovered even after a fixed time period (step ST4). (Step ST
5) If recovered, the converter 11 and the inverter 12 are each turned on (step S) on condition that the protective GTO thyristor is turned off.
(T6, ST7), the normal operation is restored (step ST8).

On the other hand, when it is detected by the overcurrent detection circuit 20 that the output of the inverter 12 becomes an overcurrent, the inverter control circuit 19 turns off the inverter 12 and the converter 11 (step ST
9). Next, due to this gate-off, the overvoltage detection circuit 25 determines whether or not an overvoltage exceeding a predetermined high set level has occurred (step ST10), and if it is determined to exceed, the inverter 12 is gated on (step ST10). ST11), if it is determined not to exceed, step S
Move to T4.

Then, in step ST11, the inverter 1
With all bridges in 2 being gated on,
As shown by the dotted arrow in FIG. 5, the secondary circuit is short-circuited and
The secondary circuit of the ESM is also short-circuited, and the induction motor operates to suppress the overvoltage. At this time, the converter 11
Turns off the gate, and the operation of the converter 11 is stopped.

On the other hand, when an accident or the like on the system side is eliminated by the operation of the transmission line breaker or the like and the above-mentioned overcurrent and the return to the low set voltage or less are made (step ST12), the inverter control circuit 19 detects the overcurrent. Based on the outputs of the circuit 20 and the overvoltage detection circuit 25, the inverter 12 is gated off (step ST13), the converter 11 and the inverter 1 are turned on.
2 to normal ignition control (steps ST6, S
T7), and the normal operation of the AESM50 is returned (step ST8).

Example 6. In addition, although the forced commutation type 12-phase voltage inverter 12 is described as the EX 6 in the above embodiment, the multi-phase type other than this may be used instead of 12 phases, and the converter 11 is not limited to the GTO method. Further, instead of the variable speed pumping machine, an application product of the AESM50, such as a flywheel generator or a frequency converter, can be used, and the same effect as that of the above-described embodiment can be obtained.

[0042]

As described above, according to the first aspect of the present invention, among the EXs that are polyphase-multigrouped, the EX of the failed group is separated from the secondary side, and the remaining normal groups are separated. Since the inverter control circuit that makes it possible to excite the secondary side by the excitation converter is provided, it is possible to obtain a variable speed pumped storage power generation with a high operating rate.

Further, according to the invention of claim 2, EX
And an inverter for converting the system voltage into a direct current and an inverter for converting the output of the converter into an alternating current, and an overvoltage detection circuit provided on the input side of the inverter, and the inverter control circuit is provided with the overvoltage detection circuit. Based on the output of the system, in the event of a system fault, the inverter gate is turned off to suppress overvoltage, and after recovery from the system fault, the inverter gate is turned off and the converter gate is turned on to restore normal operation. Since I configured it to trip the unit if the accident does not recover,
There is an effect that the circuit configuration becomes simple and the space occupied by each part of the circuit can be suppressed, so that the one that can economically control the operation of the AESM can be obtained.

Further, according to the invention of claim 3, E
A converter that constitutes X and that converts the system voltage into direct current; and an inverter that converts the output of the converter into alternating current;
By providing an overvoltage detection circuit and a protective gate turn-off thyristor provided on the input side of the inverter, the inverter control circuit, when detecting an overcurrent on the output side of the inverter or when detecting an overvoltage by the overvoltage detection circuit, The protective GTO thyristor is ignited to short-circuit the output circuit of the converter, and / or the thyristors of all bridges in the inverter are simultaneously ignited to short-circuit the secondary circuit. Since it is configured to return to normal operation and unit trip if the accident does not recover, it can handle not only a system accident but also an EX failure, and the circuit configuration is simple and the AESM can be economically controlled. There is an effect that can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a variable speed pumped storage hydropower system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a variable speed pumped storage hydropower system according to an embodiment of the present invention.

FIG. 3 is a circuit diagram showing details of the inverter in FIG.

FIG. 4 is a block diagram showing a variable speed pumped storage hydropower system according to an embodiment of the present invention.

5 is a circuit diagram showing details of the inverter in FIG.

FIG. 6 is a flowchart showing an operation flow of the variable speed pumped storage power generation system in FIG.

FIG. 7 is a block diagram showing a conventional variable speed pumped storage hydropower system.

FIG. 8 is a block diagram showing another conventional example of a variable speed pumped storage hydropower system.

[Explanation of symbols]

6 EX (excitation converter) 11 converter 12 inverter 10 overvoltage detection circuit 16, 18, 19 inverter control circuit 22 protection GTO thyristor (protection gate turn-off thyristor) 25 overvoltage detection circuit 50 AESM (AC excitation synchronous machine) S1 S6 thyristor

Claims (3)

[Claims] 1. A variable-speed pumped storage power generation system in which variable-speed pumped-storage power generation system performs variable-speed operation by controlling the secondary side of an AC excitation synchronous machine directly connected to a reversible pump turbine by a excitation converter. Among the above-mentioned excitation converters, an inverter control circuit that separates the excitation converter of the faulty group from the secondary side, and makes it possible to excite the secondary side by the remaining excitation transducers of the normal group. A variable speed pumped storage power generation system characterized by being provided. 2. A variable speed pumped-storage power generation system in which a secondary side of an AC excitation synchronous machine directly connected to a reversible pump turbine is controlled at a variable speed by controlling the secondary side of the AC excitation synchronous machine. And a converter for converting the system voltage to a direct current and an inverter for converting the output of the converter to an alternating current, an overvoltage detection circuit provided on the input side of the inverter, and an output of the overvoltage detection circuit based on the output. An inverter that turns off the gate of the inverter to suppress overvoltage, turns off the gate of the inverter and turns on the gate of the converter to restore normal operation after recovery of the system fault, and causes a unit trip if the system fault does not recover A variable speed pumped storage power generation system, which is provided with a control circuit. 3. A variable speed pumped-storage power generation system which operates at a variable speed by controlling the secondary side of an AC excitation synchronous machine directly connected to a reversible pump turbine by means of an excitation converter. And an inverter for converting the system voltage into a direct current and an inverter for converting the output of the converter into an alternating current, an overvoltage detection circuit and a protective gate turn-off thyristor provided on the input side of the inverter, and an output side of the inverter. When an overcurrent is detected or when an overvoltage is detected by the overvoltage detection circuit, the protection gate turn-off thyristor is ignited to short-circuit the output circuit of the converter, and / or the thyristors of all bridges in the inverter are simultaneously ignited. Then, the secondary circuit is short-circuited, and after the accident recovery, the inverter and converter are A variable-speed pumped storage hydropower system, which is equipped with an inverter control circuit that returns to normal operation and trips the unit if an accident does not recover.