JP3075394B2 - Variable speed pumped storage power generation system - Google Patents

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 that operates an AC excitation synchronous machine under the control of an excitation converter.

[0002]

2. Description of the Related Art FIG. 6 is a circuit diagram showing a conventional variable speed pumping system. In the figure, reference numeral 1 denotes an armature of an AC excitation synchronous machine (hereinafter referred to as AESM) 50, and 2 denotes an AESM 50.
, A reversible pump turbine directly connected to the rotor 2, 4 a shaft, 5 a transformer for an exciting converter, 6 a thyristor drive circuit for controlling the exciting current of the secondary coil. , An excitation converter (hereinafter referred to as EX), 8 is an overvoltage suppression thyristor circuit for suppressing the overvoltage of the output voltage of EX6, 9 is an arrester for suppressing the overvoltage of the output voltage, and 10 is an overvoltage detection 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. Even if the rotational speed changes, the secondary excitation by the slip is made to match the system frequency. By correcting the frequency, parallel operation with the system is enabled.

[0004] In EX6, a cycloconverter system for directly generating an alternating current from an alternating current is used. 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 suppression thyristor circuit 8 is fired according to the detection result to suppress the overvoltage.

[0005]

Since the conventional variable-speed pumped-storage power generation system is configured as described above, the system is provided with an overvoltage protection thyristor circuit 8 and an overvoltage suppression arrester 9 on the output side of the EX6. It is necessary to provide a device, which complicates the circuit configuration, increases the space occupied by each part of the circuit, and causes problems such as being uneconomical.

Further, in the system shown in FIG. 6, even if the system side accident can be dealt with, the EX6 cannot be protected, or the configuration is complicated, the occupied space of each circuit element becomes large, and it becomes uneconomical. There was a problem. In addition, the technology similar to such a conventional variable speed pumped storage power generation system is described in 1991 National Conference of the Institute of Electrical Engineers of Japan, pages 1066, 9-59 to 60, and 1070, 8 to 247 to 248.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to provide a variable speed pumped-storage power generation system capable of providing overvoltage protection with a relatively simple and small circuit configuration.

Another object of the present invention is to provide a variable-speed pumped-storage power generation system capable of simply coping with a system-side accident and realizing protection against a failure of an exciting converter.

[0009]

According to a first aspect of the present invention, there is provided a variable speed pumped storage power generation system having a converter for converting a system voltage into a direct current, and a GTO thyristor provided in each bridge together with a diode. An inverter for sequentially transferring DC, converting the output of the converter to AC power and outputting the AC power, and an overvoltage detection circuit provided on the input side of the inverter are provided, and the inverter control circuit is provided with a system based on the output of the overvoltage detection circuit. In the event of an accident, the GTO thyristor of the inverter is simultaneously fired to suppress overvoltage.

According to a second aspect of the present invention, there is provided a variable-speed pumped-storage power generation system having a converter for converting a system voltage into a direct current, and a GTO thyristor provided in each bridge together with a diode. An inverter that converts the output of the
An overvoltage detection circuit and a protection gate turn-off thyristor provided on the input side of the inverter are provided, and a protection gate is provided in the inverter control circuit when an overcurrent on the output side of the inverter is detected or an overvoltage is detected by the overvoltage detection circuit. The output circuit of the converter is short-circuited by firing the turn-off thyristor, and / or the thyristors of all the bridges in the inverter are simultaneously fired to short- circuit the secondary circuit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a variable speed pumped-storage power generation system according to Embodiment 1 of the present invention. In the drawing, reference numeral 1 denotes an armature of an AESM (AC excitation synchronous machine) 50;
Is a rotor having an AESM50 secondary coil, 3 is a reversible pump turbine directly connected to the rotor 2, 4 is a shaft, 5
Is a converter for EX, 11 is a converter for EX (excitation converter) 6, 12 is an inverter for EX6,
6 is EX, which is a converter 11, an inverter 12,
It comprises an overvoltage detection circuit 25 and a DC link capacitor 17 provided in a DC circuit on the output side of the converter 11. Reference numeral 18 denotes an inverter 1 when the DC circuit is overvoltaged.
2 is an inverter control circuit for simultaneously firing control of the GTO thyristors of all bridges.

FIG. 2 shows the inverter 12 shown in FIG.
Is a circuit diagram specifically showing GTO thyristors S1 to S6 inserted in each bridge and diodes D1 to D1.
2 and normally transfer DC sequentially to each of the thyristors S1 to S6, convert the AC power into AC power, and supply the AC power to the secondary coil.

Next, the operation will be described. Now, when an accident such as a one-line ground fault, a two-line ground fault, or a short circuit occurs on the system side, an overvoltage occurs in the secondary coil of the AESM50. At this time, in order to prevent damage to the equipment, the overvoltage detection circuit 25 detects this and outputs it to the inverter control circuit 18 to simultaneously fire the GTO thyristors S1 to S6 of all the bridges constituting the inverter 12.

For this reason, the secondary voltage at this time causes the secondary circuit to be short-circuited as shown by the dotted arrow in FIG.
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 accident on the system side is eliminated by the operation of the circuit breaker or the like of the transmission line, the inverter 12 is gated off by the inverter control circuit 18, and thereafter, both the converter 11 and the inverter 12 are controlled by normal ignition control. And the operation of the AESM 50 is continued. In this case, if the system fault continues after a certain time, the entire unit will be stopped.

Embodiment 2 It has been described that using a force commutated 12-phase voltage inverter 12 as EX6 in the first embodiment, but may be a multi-phase type other rather than 12-phase, similar to Embodiment 1 above Symbol embodiment It works.

Embodiment 3 FIG. 3 is a block diagram showing a variable speed pumped-storage power generation system according to Embodiment 3 of the present invention. In the figure, reference numeral 11 denotes an EX6 converter, and reference numeral 12 denotes E.
Inverter X6, 19 is an inverter control circuit for firing control of the thyristor of inverter 12, 17 is a DC link capacitor put in the DC circuit on the converter output side, 25
Is an overvoltage detection circuit, which has a higher set voltage than an overvoltage detection circuit 10 provided separately. Reference numeral 22 denotes a protection GTO whose ignition is controlled by the output of the overvoltage detection circuit 10.
Thyristor (protection gate turn-off thyristor), 2
Reference numeral 3 denotes a short-circuit resistor, which is connected in series with each other and connected to the DC link capacitor 17 in parallel.
Reference numeral 20 denotes an overcurrent detection circuit which is connected to the output side of the inverter 12 via the secondary current detection converter 21 of the AESM 50, detects an overcurrent, and inputs this detection signal to the inverter control circuit 19.

FIG. 4 is a circuit diagram showing the details of the inverter 12, which has GTO thyristors S1 to S6 in each bridge together with diodes D1 to D12. Is converted to AC power, which can be supplied to the secondary coil.

Next, the operation will be described with reference to the flowchart of FIG. Now, if an accident occurs on the system side, for example, one of a single-wire ground fault, a two-wire ground fault, and a short circuit,
Overvoltage or overcurrent occurs on the secondary side of the AESM50. In addition, the voltage of the DC circuit between the converter 11 and the inverter 12 also increases due to the failure of the EX6, resulting in an overvoltage.

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

Next, it is determined whether or not the DC voltage on the output side of the converter 11 has fallen below a predetermined low set level of the overvoltage detection circuit 10 due to the short circuit (step ST).
2) If the following occurs, the gate of the protection GTO thyristor 22 is turned off (step ST3).

At this time, if the level does not fall below the low set level, it is determined whether or not the AESM voltage has recovered normally after a certain period of time (step ST4). If not recovered, a unit trip is made (step ST5). When the recovery has been completed, the converter 11 and the inverter 12 are each gate-on on condition that the protection GTO thyristor 22 is gate-off (step ST6).
ST7), returning to normal operation (step ST)
8).

On the other hand, if the overcurrent detection circuit 20 detects that the output of the inverter 12 has become overcurrent, the inverter control circuit 19 turns off the inverter 12 and the converter 11 (step ST).
9). Next, due to the gate-off, the overvoltage detection circuit 25 determines whether or not an overvoltage exceeding a predetermined high set level has occurred (step ST10). If it is determined that the overvoltage has exceeded the predetermined level, 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 the bridges in 2 being gate-on,
As indicated by the dotted arrow in FIG. 4, the secondary circuit is short-circuited and A
The secondary circuit of the ESM 50 is also short-circuited, and the operation of the induction motor operates to suppress the overvoltage. 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, when an accident on the system side is eliminated by the operation of the transmission line breaker or the like and the overcurrent and the return to the low set voltage or less are performed (step ST12), the inverter control circuit 19 detects the overcurrent. The gate of the inverter 12 is turned off (step ST13) based on the outputs of the circuit 20 and the overvoltage detection circuit 25, and the converter 11 and the inverter 1
2 is returned to the normal firing control (steps ST6 and S5).
T7), the operation returns to the normal operation of the AESM 50 (step ST8).

Embodiment 4 In the third embodiment, the forced commutation type 12-phase voltage inverter 12 has been described as EX6. However, instead of the 12-phase type, a polyphase type other than this may be used, and the converter 11 needs to be limited to the GTO type. AESM50 instead of a variable speed pump
It can also be used in applications such as flywheel generators and frequency converters, and has the same effects as the above embodiment.

[0027]

As described above, according to the first aspect of the present invention, a converter for converting a system voltage into a direct current and a GTO thyristor provided in each bridge together with a diode are provided, and a direct current is sequentially transferred to each of the GTO thyristors. An inverter for converting the output of the converter into AC power and outputting the AC power, and an overvoltage detection circuit provided on the input side of the inverter, and providing an inverter control circuit with an inverter control based on the output of the overvoltage detection circuit in the event of a system failure. Since the GTO thyristor is configured to fire simultaneously to suppress overvoltage,
The circuit configuration is simplified, the space occupied by each part of the circuit can be reduced, and therefore, there is an effect that the operation of the AESM can be economically controlled.

According to the second aspect of the present invention, the converter for converting the system voltage to the direct current and the GTO
An inverter that has a thyristor with a diode, sequentially transfers direct current to each GTO thyristor, converts the output of the converter into AC power, and outputs the power, and an overvoltage detection circuit and a protection gate turn-off thyristor provided on the input side of the inverter are provided. When the inverter control circuit detects an overcurrent on the output side of the inverter or detects an overvoltage by the overvoltage detection circuit, the protective gate turn-off thyristor is fired to short-circuit the output circuit of the converter, and / or , The thyristors of all bridges are simultaneously ignited and the secondary circuit is short-circuited , so that not only system failures but also EX failures can be dealt with, and the circuit configuration is simple and economical to operate the AESM. There is an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a variable speed pumped storage power generation system according to Embodiment 1 of the present invention.

FIG. 2 is a circuit diagram showing details of an inverter in FIG. 1;

FIG. 3 is a block diagram showing a variable-speed pumped-storage power generation system according to Embodiment 3 of the present invention.

FIG. 4 is a circuit diagram showing details of an inverter in FIG. 3;

FIG. 5 is a flowchart showing a flow of an operation of the variable speed pumped storage power generation system in FIG. 3;

FIG. 6 is a block diagram showing a conventional variable speed pumped storage power generation system.

[Explanation of symbols]

6 EX (excitation converter), 10, 25 Overvoltage detection circuit, 11 converter, 12 inverter, 18, 19
Inverter control circuit, 22 GTO thyristor for protection (gate turn-off thyristor for protection), 50 AES
M (AC excitation synchronous machine), S1 to S6 thyristor.

Claims (2)

(57) [Claims] A variable-speed pumped-storage power generation system in which an AC-excited synchronous machine directly connected to a reversible pump-turbine is operated at a variable speed by controlling the secondary side of the synchronous machine with an exciting converter, the system voltage is converted to DC. A converter that has a GTO thyristor in each bridge together with a diode, sequentially transfers DC to each of the GTO thyristors, converts the output of the converter into AC power, and outputs the AC power. An inverter provided on the input side of the inverter an overvoltage detection circuit, based on an output of the overvoltage detecting circuit, a variable speed pumped storage power generation system characterized by comprising an inverter control circuit to suppress the overvoltage and simultaneously firing the GTO thyristor of the inverter during system fault . 2. A variable-speed pumped-storage power generation system in which an AC-excited synchronous machine directly connected to a reversible pump-turbine is operated at a variable speed by controlling a secondary side thereof by an exciting converter. A converter that has a GTO thyristor in each bridge together with a diode, sequentially transfers DC to each of the GTO thyristors, converts the output of the converter into AC power, and outputs the AC power. An inverter provided on the input side of the inverter An overvoltage detection circuit and a gate turn-off thyristor for protection, and an output circuit of the converter by firing the gate turn-off thyristor for protection upon detection of overcurrent at the output side of the inverter or upon detection of overvoltage by the overvoltage detection circuit. And / or all bridge thyristors in the inverter Variable speed pumped storage power generation system characterized by the provided an inverter control circuit Ru short the secondary circuit by simultaneous firing.