JPH0824408B2 - Generator protector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention determines a generator when one or more generators among a plurality of generators operating in parallel have an excitation system failure. The present invention relates to a generator protection device that is disconnected.

[Conventional technology]

FIG. 4 is a circuit diagram of a conventional generator protecting device disclosed in, for example, Japanese Patent Publication No. 51-37422. Each of the generators 1a and 1b operated in parallel has a characteristic that the voltage decreases with a delayed reactive current and increases with a reactive current as a cross current compensation. The generated voltage of the generators 1a and 1b is given to the reactive power detectors 12a and 12b, respectively, and the breaker
It is given to the bus A via 3 _a1 and 3 _b1 , and further given to the load 6 via the bus A. The output of the reactive power detector 12a is given to the average value calculation circuit 13 and the comparison amplification circuit 14a, and the output of the reactive power detector 12b is given to the average value calculation circuit 13 and the comparison amplification circuit 14b.

The output of the average value calculation circuit 13 is the comparison and amplification circuit 14
given to a and 14b. The output of the comparison amplification circuit 14a is given to the exciter 2a and the logical operation circuit 16a, and the output of the exciter 2a is given to the generator 1a. Comparative amplifier circuit
The output of 14b is given to the exciter 2b and the logical operation circuit 16b, and the output of the exciter 2b is given to the generator 1b. On the other hand, the voltage of the bus A is given to the bus voltage comparison circuit 15 to which the bus voltage setter 15a is connected, and the output of the bus voltage comparison circuit 15 is the comparison amplification circuits 14a and 14b and the logical operation circuit 1
It is given to 6a, 16b. And which gives an output of logic circuit 16a in the trip coil 3 _a2 of the circuit breaker 3 _a1, breaker logic circuit 16a, 16b is the output of the comparator amplifier circuit 16b 3 _b1
The trip coil is given to _3b2 . This logical operation circuit 1
A faulty generator is determined based on the reactive power sharing deviations from 4a and 14b and the bus voltage deviation from the bus voltage detector 15.

When the generators 1a, 1b are operated in parallel, the reactive power of the generators 1a, 1b is detected by the reactive power detectors 12a, 12b, and both outputs of the reactive power detectors 12a, 12b are output to the average value calculation circuit 13. input. As a result, the average value calculation circuit 13 compares the output obtained by calculating the reference reactive power per generator with the comparison amplification circuit 14
Give to a, 14b. The comparison amplification circuits 14a and 14b respectively compare the reference reactive power and the reactive power detected by the reactive power detectors 12a and 12b, and the reactive power of the generators 1a and 1b is larger than the reference reactive power. On the contrary, the generator with the smaller voltage is supplied with the output of the voltage increase to the exciters 2a and 2b so that the reactive power of both generators 1a and 1b is equally divided. Further, during such reactive power sharing control, the voltage of the bus A is compared with the set voltage given by the bus voltage setter 15a in the bus voltage comparison circuit 15, and if the rise or fall of the bus voltage is detected, the comparison amplification circuit is detected. The reactive power sharing control by 14a, 14b is temporarily interrupted, and the output of voltage reduction or voltage increase is generated by the excitation device 2.
It is given to a and 2b to keep the bus voltage constant.

In such an operating state, the exciter becomes above, and when the generator fails, the deviation between the reactive power and the reactive power reference value which is the output of the comparison amplification circuits 14a, 14b, that is, the reactive power sharing deviation and The deviation between the bus voltage output from the bus voltage comparison circuit 15 and the set value of the bus voltage, that is, the bus voltage deviation, is compared by the logic operation circuits 16a and 16b, respectively, and the generator that has failed according to the operation table shown in Table 1 below. Is being determined.

That is, in the case of a failure in which the voltage of the generator rises, the reactive power (kV _ar ) increases with the rise of the bus voltage (greater than the bus voltage deviation ΔV).
Is large (greater than reactive power sharing deviation + ΔkV _ar )
In the case of a failure in which one is the failed generator and the generated voltage drops, the amount of shared reactive power (kV _ar ) is small due to the decrease in bus voltage (bus voltage deviation − less than ΔV) (reactive power sharing deviation − (Smaller or larger than ΔkV _ar ) is judged to be the faulty generator and the output signal of the logical operation circuit 16a or 16b is output to the circuit breaker 3 _a1 or 3
given to the trip coil 3 _a2 or 3 _b2 of _b1 energizing it. As a result, the circuit breaker 3a or 3b operates to cut off and disconnects the failed generator 1a or 1b from the bus A.

[Problems to be Solved by the Invention]

As described above, the conventional generator protection device is configured such that when the generators are operated in parallel, even if the generator voltage is increased or decreased due to an abnormality of the exciter or the like, the generator fails. , While the bus voltage control is operating, a healthy generator compensates for the rise or fall of the voltage of the failed generator, and apparently it is difficult for the bus voltage to change, and the determination of the failed generator is delayed and sound. There is a problem that the over current trip of the generator and the faulty generator cannot be judged quickly.

If the busbar load is large, the remaining generators may suddenly become overloaded due to the disconnection of the faulty generator, which may cause inconvenience such as stall of the prime mover.

In view of the above problems, it is an object of the present invention to provide a generator protection device that can quickly and accurately determine a faulty generator regardless of bus voltage control.

[Means for solving the problem]

The generator protection device according to the present invention discriminates whether or not the generators are in parallel operation, and when the generators are in parallel operation, the generator 1
A means for calculating the reference reactive power per unit, a means for obtaining a deviation between the reference reactive power and the reactive power carried by each generator, and a deviation of the reactive power by detecting the voltage increase / decrease state of the generator. When the value exceeds a predetermined value, the direction of the deviation and the voltage increase / decrease state are logically calculated, the means for determining the faulty generator and the bus load are detected, and when the bus load exceeds the predetermined value, a priority cutoff signal is output. Then, after shutting off the target circuit breaker, and when the predetermined value is not exceeded, a means for immediately outputting the disconnection signal of the faulty generator is provided.

[Action]

According to the present invention, by this, it is determined whether or not the generators are in parallel operation, and when the generators are in parallel operation, the reactive power of each generator is calculated by the voltage and current of the generators to determine the reactive power of the generators. The reference reactive power per generator is calculated from the total sum and the preset rated capacity ratio of the generator, and the deviation between the reference reactive power and the reactive power that the generator bears is calculated, while the generator If the reactive power deviation is judged to be greater than or equal to a predetermined value, the direction of the deviation and the voltage increase / decrease status are logically operated to determine the faulty generator, and the priority cutoff signal is determined according to the size of the bus load. It is determined whether or not the output of is required.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing its embodiments. FIG. 1 is a single line connection diagram of a power supply system to which a generator protection device according to the present invention is applied. Each of the generators 1a and 1b operated in parallel has a characteristic that the voltage decreases with a delayed reactive current and increases with a reactive current as a cross current compensation.

Generator 1a, the power generation voltage of 1b is applied to the bus A via the circuit breaker 3 _a1, 3 _b1, feeder breaker 6a from the bus A, given 6b to the load 6 through the.

Further, the generated voltage and current of the generator 1a are passed through the transformer 4a and the current transformer 5a, and the generated voltage and current of the generator 1b are passed through the transformer 4a.
And the current input to the analog input section 8 of the failure determination section 11 including the digital input section 7, the analog input section 8, the calculation section 9 and the output section 10 via the current transformer 5b. The voltage of the bus A is applied to the analog input section 8 via the transformer 4c. Breaker 3 _a1 auxiliary contact 3 _a3 switching signal and breaker
The opening / closing operation signal of the auxiliary contact 3 _b3 of 3 _b1 is given to the digital input section 7. The output signals of the digital input section 7 and the analog input section 8 are given to the arithmetic section 9, and the output signal of the result of the arithmetic operation by the arithmetic section 9 is given to the output section 10.

The voltage control signal output from the output unit 10 is the excitation device 2a, 2b.
The output of the exciter 2a to the generator 1a
The output of 2b is given to the generator 1b. Also, the signal output from the output unit 10 for tripping the circuit breaker is the circuit breaker 3 _a1 , 3
It has been given to the trip coil 3 _a2, 3 _b2 of _b1.

Furthermore, the priority cutoff signal output from the output unit 10 is the power breaker.
Given to the trip circuit of 6a.

Next, the judgment procedure of the failure judgment unit 11 will be described with reference to the flowchart shown in FIG. 2 and the subroutine shown in FIG.
The computing unit 9 first checks the digital input unit 7 (S1),
Breaker 3 _a1, 3 auxiliary contacts 3 _a3 of _b1, 3 _b3 generator 1a from the opening and closing operation signal, 1b determines whether concurrent operation (S2). In the parallel operation state, the calculation unit 9 takes in the respective generated voltage and current of the generators 1a and 1b from the analog input unit 8 and the generators 1a and 1b.
Each reactive power is calculated (S3). In addition, the calculation unit 9 adds the calculated reactive powers of the generators 1a and 1b and the rated reactive power of each generator preset in the calculation unit 9 to determine whether the generators 1a and 1b have 1 Calculate the standard reactive power that each unit must bear. Then, the standard reactive power of each generator is compared with the reactive power that the generator actually bears to obtain the reactive power deviation, and if the actual reactive power is large, the generator A signal is output from the output unit 10 to the exciter 2a or 2b in order to reduce the voltage. On the contrary, when the reactive power actually burdened is small, the output unit 10 outputs a signal to the exciter 2a or 2b in order to increase the voltage of the generator. As a result, the reactive power that is actually borne is distributed to the capacity ratio of each generator. Also, the bus voltage is checked (S4), and if the bus voltage is decreasing or rising, the reactive power sharing control described above is temporarily interrupted and the exciter from the output unit 10 keeps the bus voltage constant. The signal of voltage up or down is output to 2a and 2b. Next, in the subroutine of FIG. 3 for checking the rise and fall of the bus voltage, it is judged whether or not it is in the voltage control state (S5). If the voltage is being controlled, it is judged whether or not the "rising" signal for raising the bus voltage is being output (S6), and if it is the "rising" signal, the flag that the voltage is regarded as "falling" is set (S7). , If the "falling" signal is being output, the flag that the voltage is considered to "rise" is set (S8). If it is not in the voltage control state in step (S5), it is determined whether or not the bus voltage at the predetermined time t ₁ second before has changed by the bus voltage deviation ΔV or more (S9), and if it is changed, it is determined whether or not it has risen. Then, (S10), if the actual bus voltage rises, a flag that regards the voltage as "increase" is set (S7), and if it drops, the flag that regards the voltage as "fall" is set (S8). In addition, if there is no change in bus voltage deviation ΔV or more in step (S9), the voltage rises.
Both the falling flags are reset (S11). After finishing such a subroutine, the voltage "rises"
If the flag of 1) or the flag of "falling" is set (S12), that is, if the bus voltage is rising or falling, it is determined whether the reactive power (kV _ar ) sharing is unbalanced (inappropriate) ( S13). If the sharing is unbalanced, it is determined whether or not it has increased compared to t ₁ seconds before (S14), and if it has increased, it is determined whether or not the increased amount is equal to or greater than a predetermined value (S15). If the amount of increase is equal to or greater than the predetermined value, the generator in failure is determined (S17), and it is confirmed whether or not the determination result is two consecutive times to prevent malfunction (S18). When the amount of increase is less than or equal to the predetermined value, it is determined whether the increase state has passed a predetermined time t ₂ seconds (same as or slightly longer than t ₁ ) (S16). Then, when the increase state has passed t ₂ seconds, it is determined as a faulty generator (S19).

 Judgment of the faulty generator is performed by the calculation table shown in Table 2.

That is, when the voltage “fall” flag is set, the reactive power deviation ΔkV _ar is in the (−) direction, that is, the reactive power sharing is less, or the reactive power sharing is decreasing (−) for a time t ₂ seconds. The one with the fault is the faulty generator. Also, when the voltage “rising” flag is set, the reactive power deviation ΔkV _ar
Is in the (+) direction, that is, the direction in which the reactive power share is large or the direction in which the reactive power share is increasing (+) for time t ₂ seconds is determined to be the faulty generator.

Next, the size of the bus load is calculated by summing the active powers shared by the generators 1a and 1b, and this ratio exceeds the set value after the faulty generator is disconnected Whether or not it is determined (S20), if it is equal to or more than the set value, a priority cutoff signal is output (S21), and the power breaker 6a that is the target of the priority cutoff is tripped. If the value does not exceed the set value, a signal to disconnect the faulty generator is immediately issued to trip the breaker.

Then, for a generator that is determined to be a faulty generator, the bus A
A signal is given to the trip coil of the circuit breaker 3 _a1 or 3 _b1 connected to the circuit to cause the circuit to perform the circuit breaking operation, and the faulty generator is disconnected from the bus bar A (S22) for protection. Power supply to the load 6 is continued by a sound generator.

If the voltage rising / falling flag is reset in step (S11), that is, if the bus voltage deviation ΔV or less, it is determined that the generator is normal and the determinations in step (S13) and thereafter are not performed.

In this way, when determining a faulty generator, after confirming that the bus voltage is in the rising or falling state, it is judged whether the actual sharing state of the reactive power of each generator is proper or not. Since it is decided, even during the control operation of the bus voltage,
It is possible to quickly determine a faulty generator without making an erroneous determination. Further, since the reactive power of the generator is directly calculated by the voltage and the current of the generator, a separate power converter is not required and the reactive power can be obtained quickly and with high accuracy.

〔The invention's effect〕

As described in detail above, according to the present invention, the generator operating in parallel has a failure such that the voltage rises or falls due to the abnormal operation of the excitation system, and even if the bus voltage is controlled at that time, the Accurately determine the faulty generator. Furthermore, when the bus bar load exceeds the specified value, the problem that the remaining generator is overloaded and trips or the prime mover is stalled is output after the priority breaker signal is output to shut off the target breaker. , It is possible to improve the reliability of a power supply system that operates a plurality of generators in parallel.

[Brief description of drawings]

FIG. 1 is a single line connection diagram of a power supply system to which the generator protection device of the present invention is applied, FIG. 2 is a flow chart showing the determination contents of a failure determination unit, and FIG. 3 is a subroutine for checking rise / fall of bus voltage. FIG. 4 is a single wire connection diagram of a conventional power supply system. 1a, 1b …… Generator, 2a, 2b …… Exciter, 3 _a1 , 3 _b1 …… Circuit breaker, 3 _a3 , 3 _b3 …… Auxiliary contact, 6 …… Load, 6a, 6b …… Power breaker, 7 ... Digital input section, 8 ... Analog input section, 9 ... Arithmetic section, 10 ... Output section, 11 ... Failure determination section In the drawings, the same reference numerals indicate the same or corresponding portions.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-51-96008 (JP, A) JP-A-59-92718 (JP, A) JP-A-60-82033 (JP, A) JP-A-62- 16027 (JP, A) JP 63-234833 (JP, A) JP 63-242126 (JP, A) JP 1-164233 (JP, A) JP 45-17503 (JP, B1) Japanese Patent Publication No. 45-18498 (JP, B1) Japanese Patent Publication No. 51-37422 (JP, B1) Japanese Patent Publication No. 56-19185 (JP, B1)

Claims (1)

[Claims] 1. A generator protection device, which is connected to a busbar through a circuit breaker and determines a generator when a plurality of generators operating in parallel have an excitation system failure, Means for discriminating whether or not the generators are in parallel operation, and calculating the reference reactive power per generator when in the parallel operation state, and the reference reactive power and the reactive power which each generator bears. The voltage increase / decrease status of the generator depends on the output of the voltage control signal when the generator is in voltage control, and the voltage increase / decrease status from a predetermined time before when the voltage control is stopped. And a means for determining the deviation of the reactive power when the deviation of the reactive power is equal to or greater than a predetermined value, and a means for judging the faulty generator, and detecting the bus load, When the specified value is exceeded, a priority cutoff signal is output and After blocked the breaker, also the generator protection devices, characterized in that it comprises a means for outputting a disconnection signal for fault generator immediately when it does not exceed a predetermined value.