JP2510440B2 - Protection relay operation simulation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection relay operation simulation method for simulating the operation of main protection and backup protection relays in a training simulator for conducting skill training on system operation of power supply staff and control staff. is there.

[0002]

2. Description of the Related Art FIG. 3 is a flow chart showing an operation simulation method of a conventional protection relay, in which ST2 is a fault equivalent impedance calculation step, ST3 is a positive phase admittance matrix calculation step including the fault equivalent impedance, and ST4. Is a positive phase circuit voltage calculation step, ST5 is a negative phase or zero phase circuit fault current calculation step, ST6 is a negative phase or zero phase circuit voltage and current distribution calculation step, S
T7 is a three-phase voltage / current distribution calculation step of the three-phase circuit, S
T8 is an operation determination step for determining the operation of the main protection / reserve protection relay unit alone, ST9 is an operation presence / absence determination step for determining the presence / absence of operation of the relay unit alone, and ST10 is a timer for Δt.
ST11 is a relay sequence determination step for determining whether or not a relay sequence is established, ST12 is a circuit breaker trip step for tripping the corresponding circuit breaker, and ST13 is a failure continuation determination step for determining failure continuity. .

Next, the operation will be described. There are 1-wire ground fault, 2-wire ground fault, 2-wire short-circuit, 3-wire ground fault (short circuit), etc. in power system accidents.
First, the fault equivalent impedance Zf consisting of a negative phase circuit and a negative phase circuit to be added to the fault point of the positive phase circuit is calculated (step ST2). In a 3-wire ground fault (short circuit), Zf = 0, but in a 1-wire ground fault, Zf = Zf ² + Zf ⁰ , in a 2-wire ground fault, Zf = Zf ² · Zf ⁰ / (Zf ² + Zf ⁰ ), 2-wire In a short circuit, Zf = Zf ² . Here, Zf ² is the equivalent impedance of the anti-phase circuit viewed from the accident point, and Zf ⁰ is the equivalent impedance of the zero-phase circuit viewed from the accident point.

Next, the admittance matrix when the fault equivalent impedance Zf is added to the fault point of the positive-phase circuit is calculated (step ST3), and then the equation 1 of the positive-phase circuit network is solved to calculate the voltage at each node. Is calculated (step ST4). Here, g is a generator rear node, f is an accident node, l is a load, a general node, I is a node current, Y is an admittance,
V is a node voltage.

[0005]

[Equation 1]

In equation 1, the unknowns are Ig, I
f and Vl. Now, expanding Expression 1, it becomes Expressions 2 and 3.

[0007]

[Equation 2]

Therefore, from Equation 3, Equation 4 is obtained.

[0009]

(Equation 3)

Then, substituting equation 4 into equation 2 yields equation 5.

[0011]

[Equation 4]

Next, If and Zf ² and Zf ⁰ obtained by the equation 5 are used.
To calculate the fault current of the anti-phase or zero-phase circuit (step ST5), and then calculate the node voltage and branch current of the anti-phase or zero-phase circuit from the fault current of the anti-phase or zero-phase circuit and the admittance matrix. (Step ST6). Then, the node voltage and branch current of the positive-phase or negative-phase or zero-phase circuit are converted into the node voltage and branch current of the a, b, and c phases (step ST7). This completes the calculation of the input voltage and current of the relay.

Next, the voltage and current at the relay installation point are input to a program simulating the main protection / reserve protection relay unit to determine the operation (step ST8), and if there is no operation, the processing is terminated and the operation is performed. If yes, the process proceeds to step ST10 (step ST9), and the timer is updated by Δt to determine whether the relay operation time limit has been reached (step ST10). Next, it is determined whether or not the final output of the relay sequence is output (step ST11), and if not output, the process returns to step ST10, and if it is output, shutoff that should be tripped when the relay operates. The device is picked up from the table and the circuit breaker is shut off (step ST12). After this, it is judged whether or not the failure is still continuing (step ST13). If the failure is continuing, the process returns to step ST2 and subsequent steps, and if the failure stops, the process ends.

[0014]

Since the conventional operation simulation method of the protection relay is carried out as described above, the number of nodes increases significantly when the system scale increases, which results in a long calculation time. There was a problem that it could not be applied to the training simulator.

The present invention has been made in order to solve the above problems, and realizes application to a training simulator by reducing the number of nodes for circuit network calculation and accelerating the operation simulation of a protection relay. The purpose is to obtain a protection relay operation simulation method that can be performed.

[0016]

A method of simulating the operation of a protection relay according to the present invention is designed to detect the vicinity of a fault section before calculating the fault equivalent impedance of a negative-phase circuit and a zero-phase circuit to be added to a fault point of a positive-phase circuit. In order to be able to calculate only the voltage and current, the normal-phase circuit, the negative-phase circuit, and the zero-phase circuit are subjected to contraction processing to limit the operation of the main protection and backup protection relays.

[0017]

In the reduction processing of the positive-phase, negative-phase, and zero-phase circuits according to the present invention, it is sufficient to calculate only the input voltage and current of the protection relay installed near the fault point, so that the number of circuit nodes is greatly reduced. Therefore, the simulation of the protection relay operation can be executed at high speed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, ST1 is a reduction step for performing reduction processing of positive-phase, negative-phase, and zero-phase circuits, ST2 is a fault equivalent impedance calculation step, ST3 is a positive-phase admittance matrix calculation step including the fault equivalent impedance, and ST4.
Is a positive phase circuit voltage calculation step, ST5 is a negative phase or zero phase circuit fault current calculation step, ST6 is a negative phase or zero phase circuit voltage and current distribution calculation step, and ST7 is a three phase voltage and current distribution of a three phase circuit. Calculation step, ST8 is the main protection,
An operation determination step for determining the operation of the backup protection relay unit alone, ST9 is an operation presence / absence determination step for determining the presence / absence of operation of the relay unit alone, ST10 is a timer updating step for updating the timer by Δt, and ST11 is the presence / absence of establishment of the relay sequence. A relay sequence determination step for determining, ST12 is a circuit breaker trip step for tripping the corresponding circuit breaker, and ST13 is a failure continuation determination step for determining continuation of failure.

Next, the operation will be described. First, in the event of a power system failure, the normal phase, negative phase, and zero phase circuits are contracted (step ST1). The concept of this contraction processing is as follows. Now, in an electric power system having three generators A, B, and C as shown in FIG. 2, it is assumed that an accident occurs in a node and a transmission line between the nodes. In this case, it is not necessary to simulate the protection relay operation of the entire system even if the failure of the main protection operation or the inoperability of the circuit breaker is considered.
Between the node as the next section adjacent to the accident section,
It is sufficient to simulate the operation of the main protection and backup protection relays of only the transmission lines between-,-, and-.

This is derived from the protection range of the main protection and backup protection relay, and the main protection protects its own section,
The first stage of the backup protection relay has its own zone, the second stage has 130% of its own zone, and the third stage has two zones including its own zone. Further, with regard to the protection of backup equipment, the operation time period is set longer in the order of the first stage, the second stage, and the third stage.

The reduction process will be described below with reference to FIG. Now, if the formula of the positive-phase network is made, it becomes like the formula 6, and if the formula 6 is rearranged, the formula 7 is obtained.

[0022]

(Equation 5)

[0023]

(Equation 6)

Further, by rewriting the equation 7, the equation 8 is obtained.

[0025]

(Equation 7)

Therefore, in this equation 8, Vg, In,
Il is known and Ig, Vn, and Vl are unknown, but if contracted, Equation 9 is obtained.

[0027]

(Equation 8)

As is clear from the equation (9), the dimension of the linear equation is reduced from 14 dimensions in the equation (6) to five dimensions. As a result, in the actual system, the number of nodes reaches several hundreds, and the dimension of the simultaneous linear equations is reduced to about 1/100. Then, this reduction processing may be performed only once. Thereafter, as in the conventional case, the processes from step ST2 onward are executed, and when it is determined in step ST13 that the failure continues, in step ST1, the above-mentioned normal-phase, anti-phase, and zero-phase circuits are contracted. After the processing is executed, the processing after step ST2 is repeated again.

[0029]

As described above, according to the present invention, before calculating the failure equivalent impedance of the negative-phase circuit and the zero-phase circuit which should be added to the fault point of the positive-phase circuit, the voltage and current only near the fault section are calculated. As it can be calculated, the normal phase circuit, the negative phase circuit, and the zero phase circuit are contracted to simulate the operation of the limited main protection and backup protection relay, so the dimension of the simultaneous linear equations is greatly reduced. Therefore, there is an effect that a main protection / reserve protection relay operation can be simulated at high speed.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation simulation method of a protection relay according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a reduction processing method corresponding to an accident in a power system.

FIG. 3 is a flowchart showing an operation simulation method of a conventional protection relay.

[Explanation of symbols]

 ST1 Reduction processing step ST2 Fault equivalent impedance calculation step ST4 Positive phase circuit voltage calculation step ST5 Fault current calculation step ST6 Voltage and current distribution calculation step ST7 Three-phase voltage and current calculation step ST8 Operation determination step ST10 Timer update step ST11 Relay sequence determination Step ST12 Circuit breaker trip step ST13 Failure continuation determination step

Claims (1)

(57) [Claims] 1. A fault equivalent impedance calculating step of calculating fault equivalent impedances of a negative phase circuit and a zero phase circuit to be added to a fault point of the positive phase circuit, and a positive voltage calculating each node voltage using the fault equivalent impedance. Phase circuit voltage calculation step, failure current calculation step of calculating a failure current of the negative phase circuit or zero phase circuit based on the above node voltage calculation formula, and node of the negative phase circuit or zero phase circuit using the above failure current The voltage and current distribution calculation step for calculating the voltage and the branch current, and the three-phase voltage for obtaining the node voltage and the branch current of the three-phase circuit based on the node voltage and the branch current of the positive phase circuit, the negative phase circuit, and the zero phase circuit, In the current calculation step and the program that simulates the main protection and backup protection relay unit, the voltage at the protection relay installation point,
An operation determination step of inputting a current and determining an operation; a timer updating step of updating a timer to determine whether or not the operation time limit of the protection relay has been reached when there is an operation based on the above operation determination result; The relay sequence determination step to determine whether the final output of the relay sequence of the protection relay is output, and when the final output is output, the specified circuit breaker picked up from the table when the protection relay operates. In a protection relay operation simulation method that includes a circuit breaker trip step to trip and a failure continuation determination step that determines whether the failure continues and, if it continues, repeats the above steps. Before the calculation of the equivalent impedance of the failure, it is possible to calculate the voltage and current only in the vicinity of the fault section. , Reverse-phase circuit, the main protection is limited by contraction processing the zero-phase circuit, the operation simulating method of protection relay which comprises carrying out the operation simulation of the backup protection relays.