JPH08289456A - Setting calculation system for power system protective relay - Google Patents

Abstract

PURPOSE: To provide a system for calculating the setting of protective relay in any operating pattern. CONSTITUTION: The setting calculation system for power protective relay comprises a setting reference calculation means 100 for determining severest system conditions for the duty of a protective relay to be set and an electric quantity inputted to the objective relay under the severest system conditions, means 300 for inputting a basic setting formula being set by an operator through an input unit, and means 200 for calculating the setting value of the protective relay according to the basic setting formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power system protection relay settling calculation system to which an electronic computer is applied.

[0002]

2. Description of the Related Art In order for a protection relay of a power system to achieve a required function, it is necessary to satisfy an operating duty and a non-operating duty. That is, while correctly detecting an accident that has occurred within the protection zone (operation duty), it must never operate (health duty) when the sound is healthy and for an accident outside the protection zone. For this reason, in setting the protection relay, various system conditions are assumed and the load current, fault current, etc. are carefully examined.

In order to precisely and efficiently perform such work,
A computer system and a program for calculating the set value of the protection relay have been developed. The outline will be described by taking a program for setting a distance relay (impedance relay) as an example. The distance relay settled here is installed on a certain power transmission line, and the next bus fault is an operation duty and the next bus fault is a non-operation duty.

(1) First, the settling program searches for the next bus and the next bus starting from the relay installation point. Usually, there are a plurality of secondary buses, and when the line is a multi-terminal line, there are a plurality of secondary buses.

(2) Then, the failure calculation is executed by designating the next bus and the next bus that have been searched for as fault points one by one.
In each case, find the impedance observed by the relay to be settled. The symmetric coordinate method is widely used for failure calculation.

(3) The maximum value of the impedance observed by the relay in the case of a secondary bus fault is determined, and this is used as the settling reference value for the operational responsibility. There is also an example in which a value obtained by multiplying a predetermined safety coefficient is used as the settling reference value.

(4) The minimum value of the impedance observed by the relay in the case of a secondary bus bar failure is determined, and this is used as the settling reference value for the non-operation duty. There is also an example in which a value obtained by multiplying a predetermined safety coefficient is used as the settling reference value.

(5) "Settling reference value of operation duty <Settling value <
The settling value satisfying the "setting reference value of non-operation duty" is obtained under the constraint of the settling range of the relay, and the process is ended. In most cases, there are multiple set values that satisfy the above equation. In this case, if a value that is as close as possible to the settling reference value for the non-operation duty is selected, high-sensitivity settling will be performed, so this method is often used. The settling range may be defined in a database or set on the CRT screen every time calculation is performed.

Although a distance relay is taken as an example here, since an actual protection relay device is constructed by combining relays of various operating principles, settling guidelines corresponding to individual operating principles are set, In response to this, various settling programs are prepared.

[0010]

The "distance relay in which the next bus fault is the operation duty and the next bus fault is the non-operation duty" given as an example in the prior art is one of the backup equipment protection second It is a protection relay called a dan. In this electric utility, the responsibilities of the second stage of backup protection are unified as above in most systems, but in some systems, such as the terminal system, the next bus is operated as an operation duty exceptionally. ing.

When this electric engineer introduces the conventional power system protection relay settling calculation system, the relays which are operating exceptionally are excluded from the calculation target, or they are dedicated to the exceptional relays. You will be forced to choose whether to install the program.

[0012] If the former is selected, the system configuration becomes easy, but in reality, there are many exceptional operations that differ for each protection relay method, so the calculation target system is considerably limited. Will end up. Therefore, the latter is selected, but in this case, the system becomes complicated, which is disadvantageous in terms of maintainability and economy.

Next, the problem when the settling value is calculated will be described. In the conventional technology, when there are multiple settling values that satisfy the obligation, the value with the highest sensitivity is adopted, but in this method, there is little margin for non-operation obligations, which may lead to malfunction. There is a nature. Although it has been described that there is an example in which the safety standard is multiplied to obtain the settling reference value, in that case, the operator may erroneously set the safety coefficient.

Contrary to the above, the settling reference value may deviate from the settling range of the relay in some cases. In this case, since the upper limit value or the lower limit value of the settling range is adopted as the settling value, all the responsibilities cannot be satisfied under the settling value. Therefore, the operator needs to consider the replacement of the relay or measures for system operation, but conventionally, no confirmation or notification has been made for that purpose.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power system protection relay settling calculation system capable of calculating protection relays of any operation mode with a simple configuration. There is.

[0016]

A power system protection relay settling calculation system according to [Claim 1] of the present invention is a system condition that is the most severe against the responsibility of a protection relay that is a settling target, and a settling target under that condition. Basic formula set by the operator through a settling reference value calculating means for obtaining the amount of electricity input by the protection relay and an input device such as a CRT display device (hereinafter referred to as CRT display device) equipped with a display unit if necessary. And a settling value determining means for calculating the settling value of the protection relay according to the settling basic equation.

A power system protection relay settling calculation system according to [Claim 2] of the present invention is [Claim 1] in which a settling basic expression registration means for registering a settling basic expression as a mathematical expression name and a registered mathematical expression name. A basic settling formula input means for inputting is provided.

In the power system protection relay settling calculation system according to [Claim 3] of the present invention, in [Claim 1], when there are a plurality of settling values satisfying the duty, the safety factor and the non-working duty for the duty of operation are provided. It is equipped with a safety settling means that adopts a settling value with which the safety factor for Eq.

In the power system protection relay settling calculation system according to [Claim 4] of the present invention, in [Claim 1], it is confirmed whether or not the settling value as the calculation result satisfies all the obligations, and at least If not satisfied, a settling value validity checking means is provided to notify the operator of that.

[0020]

In the power system protection relay settling calculation system according to [Claim 1] of the present invention, the settling reference value calculation means is the most severe system condition against the responsibility of the protection relay to be settling and the settling target under that condition. The amount of electricity input to the protection relay, that is, the settling reference value is obtained. The settling value determination means substitutes the settling reference value obtained by the settling reference value calculation means into the settling basic expression input by the settling basic expression inputting means through the CRT display device, and calculates the settling value of the protection relay.

In the power system protection relay settling calculation system according to [Claim 2] of the present invention, the settling basic formula registration means is activated at the request of the operator, and the settling basic formula corresponding to the mathematical expression name is displayed via the CRT display device. To register. Similarly, upon the operator's request, the settling basic equation input means is activated, the mathematical expression name is input through the CRT display device, and the mathematical expression name is replaced with the settling basic expression registered by the settling basic expression registering means.

In the power system protection relay settling calculation system according to [Claim 3] of the present invention, the safe settling means is activated when there are a plurality of settling values satisfying the obligation in the settling value determining means of [Claim 1]. However, the safety settling means adopts a settling value at which the safety factor for operating duty and the safety factor for non-operating duty are as equal as possible.

In the power system protection relay settling calculation system according to [Claim 4] of the present invention, the settling value determining unit of [Claim 1] activates the settling value validity checking unit after the settling value is calculated. The settling value validity checking means checks whether or not the settling value, which is the calculation result of the settling value determining means, satisfies all responsibilities,
If at least not satisfied, notify the operator to that effect.

[0024]

Embodiments Embodiments will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a power system protection relay settling calculation system according to [Claim 1] of the present invention. In FIG. 1, reference numeral 100 is a settling reference value calculation means, 200 is a settling value determination means, and 300 is a settling basic expression input means, both of which are realized as a computer program. The equipment database 1 stores the connection state of the electric power system and equipment constants.

The power flow condition file 2 stores data such as generator output, load power, and phasing equipment amount. The settling reference value file 3 is for three sections ahead of the settling terminal (equipment where the relay to be set up is installed), that is, the next bus, the next bus, the bus fault to the next bus, and the fault in its own section, respectively. In this case, various electric quantities observed at the settling terminal are stored, and the configuration is shown in FIG. 2. For convenience of description, details will be described together with the operation.

The basic settling equation file 4 stores the operation obligation conditional expression and the non-operation obligation conditional expression of the relay to be settled, and its configuration is as shown in FIG. As shown in FIG. 3, in the present embodiment, up to four conditional expressions can be stored, and each conditional expression has a flag indicating whether the expression is an operation obligation conditional expression or a non-operation obligation conditional expression. .

The settling terminal file 5 stores the settling range of the settling terminal relay, and its configuration is shown in FIG. Since the setting of the relay is performed by switching the taps, the setting range is the upper and lower limit values and the step value (tap step width). 4 shows the settling range in the case of a distance relay as an example,
Instead, using an undervoltage relay or an overcurrent relay as an example,
The configuration of this embodiment does not change.

The settling terminal actually stores the equipment code of the terminal in the equipment database 1.
In, the name of the equipment is described. The settling value file 6 is a file that stores the settling result. Although not shown in FIG. 1, the power flow condition file 2 and the settling terminal file 5 are data referred to and updated from the CRT display device 99.

Next, the operation of this embodiment will be described. First, the function of the settling reference value calculating means 100 will be described with reference to FIG.
In step S1, the equipment database / power flow condition file is read, and in step S2, the system states are all arranged and edited in correspondence with the node / branch number to create a so-called node branch model.

Next, in step S3, Newton-Raphson (NR) power flow calculation is executed to obtain a solution. The result of the power flow calculation will be described as the pre-fault voltage at the fault point and the load current of the branch in the fault calculation performed in steps S5 and S6.
3 may be omitted. In that case, the pre-fault voltage in the fault calculation is treated as the rated voltage and the load current is treated as zero.

Then, in step S4, the system is searched and a fault point is set. Taking the case where the settling terminal is a line as an example, the failure points are as follows. Own end of the section, middle point, partner end (all for main protection relay setting). Next busbar, next busbar, next busbar (all for backup protection relay setting).

At each failure point, a failure calculation of a three-phase short circuit (3LS) is performed in step S5, and a one-line ground fault (1LG) failure is performed in step S6. The fault calculation method uses the symmetric coordinate method. That is, by determining the positive-phase and zero-phase driving point impedances Z1 and Z0 of the fault point and considering that the negative-phase component is equal to the positive-phase component, the fault point current at the time of three-phase short circuit and the fault point at the one-line ground fault The current can be obtained by Eqs. (1) and (2), respectively.

[0033]

## EQU1 ## IF ₁ = E / Z ₁ , IF ₂ = IF ₀ = 0 (1) IF ₁ = IF ₂ = IF ₀ = E / 2 Z ₁ + Z ₀ (2) where E: Pre-fault voltage at the fault point. IF ₁ , IF ₂ , IF ₀ : Positive phase, negative phase, zero phase current at the fault point.

At the time of a failure, the current at the failure point is shunted to each branch to cause a voltage drop at each node.
The voltage drop at each node in the symmetrical equivalent circuit can be obtained by solving Eq. (3).

## EQU00002 ## [.DELTA.V] = [Z] [IF] (3) where [.DELTA.V]: column vector of the amount of voltage drop at each node. [Z]: Node impedance matrix. [IF]: Column vector of each node current (fault point current enters the element of the fault point node, and all other elements are 0).

Steps S5 and S6 are repeated processing for the number of failure points, and the calculation result is stored in the file each time. If it is determined in step S7 that the repetition has ended, the process proceeds to step S8, and the failure calculation results obtained thus far are used to calculate the magnitudes of the current, voltage, and impedance for each of the section, the next bus, the next bus, and the next bus. Is used as a key to create a settling reference value file shown in FIG. 2, and the process is completed.

The settling basic expression input means 300 writes the settling basic expression input from the CRT screen into the settling basic expression file shown in FIG. 3, and activates the settling value determining means 200. The settling value determination means 200 refers to the settling basic equation file 4 to take out the electric quantity settling in the settling basic equation from the settling reference value file 3, and adopts a tap value satisfying the settling basic equation as the settling value.

When there are a plurality of tap values that satisfy the settling basic equation, the tap value closest to the non-operation duty is adopted. If the upper and lower limits of the setting range are exceeded, the upper and lower limits are adopted. The settling result is written in the settling file 6, and the settling value determination means 200 ends the process.

The above contents are repeated, but for convenience, FIG.
Although an example of the distance relay is described in FIG. 4, the configuration of FIGS. 3 and 4 does not change whether the target relay is an overcurrent relay or an undervoltage relay. Therefore, according to the present embodiment, various relays can be settled with a simple configuration.

FIG. 6 is a block diagram of an embodiment of the power system protection relay settling calculation system according to [Claim 2] of the present invention. 6, the same parts as those in FIG. 1 and the corresponding parts are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 6, a settling basic formula registration means 400 and a formula name registration file 7 are added to FIG. Hereinafter, description will be added focusing on the differences. The mathematical expression name registration file 7 is as shown in FIG.
This is a file that defines mathematical formula names and the corresponding basic settling formulas.

Next, the operation will be described. Basic setting registration method
400 writes the formula name and the corresponding settling basic formula in the formula name registration file 7 according to the operator's request via the CRT display device 99. On the other hand, the settling basic formula input means 30
For 0, in [Claim 1], only the basic settling equation is input, but here it is also possible to enter the mathematical expression name. If there is an input of the mathematical expression name, refer to the mathematical expression name registration file 7. And obtain the corresponding settling basic formula.

FIG. 7 shows, as an example, the basic settling equation for the second stage of the short circuit detection distance. Of course, this basic settling equation is common to most of the second stage of the short circuit detection distance of the system. Therefore, the operability can be improved by replacing this with the formula name.

FIG. 8 is a block diagram of an embodiment of the power system protection relay settling calculation system according to [Claim 3] of the present invention. 8, the same parts as those in FIG. 1 and the corresponding parts are designated by the same reference numerals and the description thereof will be omitted. In FIG. 8, the safety settling means 500 is added to FIG.

Next, the operation will be described. Settling value determination means 20
If there are multiple setpoints that satisfy the obligation at 0,
The settling value determination means 200 activates the safety settling means 500. It should be noted that, although it will be noted at the beginning, it is not appropriate to estimate the safety factor in advance with the settling reference value when carrying out the present embodiment. Therefore, the safety factor of the basic settling equation has been removed in advance.

The safety settling means 500 selects the tap value so that the safety factor expected for the operation duty and the safety factor expected for the non-operation duty are equal. Now, assuming that the operation duty settling reference value is P, the non-operation duty settling reference value is Q, and the safety factor is S, ideally equation (4) holds, and if equation (4) is further transformed, ) It becomes an expression. Therefore, the tap value T is given by equation (6).

[0045]

[Equation 3] P (1 + S) = Q (1-S) (where P <Q) (4) S =-(P-Q) / (P + Q) (5) T = P (1 + S) = 2Q / (P + Q) …………… (6)

In reality, it is rare that there is a tap that matches T. Therefore, comparing the lower side and the upper side of T, the
A tap value close to is adopted as the settling value. As described above, according to the present embodiment, human error in the safety factor and erroneous settling due to over-priority of any responsibility do not occur. It should be noted that if a function is added to this embodiment and a certain safety factor cannot be secured, a warning is given to the operator, which is more kind.

FIG. 9 is a block diagram of an embodiment of a power system protection relay settling calculation system according to [Claim 4] of the present invention. 9, the same parts as those in FIG. 1 and the corresponding parts are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 9, a settling value validity checking means 600 and a failure calculation result 8 are added to FIG.

The failure calculation result 8 is obtained in steps S5 and S of FIG.
The data accumulated by 6 and the settling reference value calculating means 10
0 is the result of all failure calculations performed in the course of execution. The data items of failure calculation result 8 are the current and voltage introduced by the relay to be set and the distance measurement impedance as shown in Fig. 10.

Next, the operation will be described. Settling value determination means 20
After 0, the settling value validity checking means 600 is started after the settling value is calculated. The settling value validity checking means 600 refers to the failure calculation result 8 and checks whether or not the settling basic expression stored in the settling basic expression file 4 is satisfied for each failure calculation result. In this case, regarding the operation responsibility, since the relay of the failure phase must operate originally, only the relay of the failure phase is confirmed.

On the other hand, regarding the non-operation duty, all three phases are confirmed regardless of the failure phase. When the confirmation is completed for all failure calculations, the failure points are displayed on the CRT display device 99 for at least failure calculations that are not satisfied. According to the present embodiment, the operator can recognize the problematic point in system protection when the optimum settling cannot be performed due to the restriction of the settling range of the relay.

[0051]

As described above, according to the present invention, it is possible to provide a power system protection relay settling calculation system having a simple structure and good operability and calculation accuracy, which reduces the practical work of an electric utility. And, it can contribute to further improvement of supply reliability.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of [claim 1] of the present invention.

FIG. 2 is a configuration diagram of a settling reference value file according to an embodiment of [claim 1] of the present invention.

FIG. 3 is a configuration diagram of a settling basic expression file according to an embodiment of [Claim 1] of the present invention.

FIG. 4 is a configuration diagram of a settling terminal file according to an embodiment of [Claim 1] of the present invention.

FIG. 5 is a flowchart of the settling reference value calculation means according to the embodiment of [Claim 1] of the present invention.

FIG. 6 is a configuration diagram of an embodiment of [claim 2] of the present invention.

FIG. 7 is a configuration diagram of a mathematical expression name file according to an embodiment of [Claim 2] of the present invention.

FIG. 8 is a configuration diagram of an embodiment of [claim 3] of the present invention.

FIG. 9 is a configuration diagram of an embodiment of [claim 4] of the present invention.

FIG. 10 is a configuration diagram of a failure calculation result according to the embodiment of [Claim 4] of the present invention.

[Explanation of symbols]

 1 Equipment database 2 Power flow condition file 3 Settling reference value file 4 Settling basic formula file 5 Settling terminal file 6 Settling value file 7 Formula name registration file 8 Failure calculation result 99 CRT display device 100 Settling reference value calculation means 200 Settling value determination means 300 Settling basic expression input means 400 Setting basic expression registration means 500 Safety setting means 600 Settling value validity checking means

Claims (4)

[Claims] 1. In a power system protection relay settling calculation system for calculating an appropriate settling value of a protection relay of a power system using an electronic computer having an input device, the system that is the most severe against the responsibility of the protection relay to be settled. Settling reference value calculating means for obtaining the amount of electricity input to the protection relay to be settled under that condition, settling basic equation inputting means for inputting the settling basic equation set by the operator via the input device, and settling basic equation A power system protection relay settling calculation system having settling value determining means for calculating a settling value of a protection relay according to the above. 2. A settling basic expression registration means for registering a settling basic expression as a mathematical expression name, and a settling basic expression input means for inputting a registered mathematical expression name.
The power system protection relay settling calculation system described. 3. A safety settling means for adopting a settling value that equalizes a safety factor for a working duty and a safety factor for a non-working duty when a plurality of settling values satisfying the duty are present is added. The power system protection relay settling calculation system described in 1. 4. A settling value validity confirming means for checking whether or not the settling value as a calculation result satisfies all responsibilities, and at least notifying the operator if not, is added. The power system protection relay settling calculation system according to claim 1.