JPH09261871A - Lead-in bus bar voltage selection method in system control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead-in bus bar voltage selection method in system control wherein a proper operation input can be always fetched even if there is a defect inside. SOLUTION: The bus bar voltages are fetched into a relay processor from bus bars A, B which are jointly used, through PT. With one of the voltages as a representative input, a relay operation is conducted for controlling a system (8). At that time, a means for detecting an abnormality in each lead-in circuit is installed to find out if there is an abnormality (1, 4, 6) in each lead-in circuit. In the case that there is an abnormality, the input bus bar voltage is switched to 97 another one, which is input for relay operation (4, 5). The bus bars are put in order (2, 5, 9) and the one which is earlier in the order is fetched as the representative input.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an introduction bus voltage selecting method in system control for selecting a bus voltage to be introduced into a relay arithmetic processing unit in automatic control of a power system, for example, automatic control of voltage / reactive power (VQ). .

[0002]

2. Description of the Related Art A VQ device is for maintaining proper system voltage and sharing of economical reactive power. Generally, a voltage / reactive power control device (load tap switching transformer, synchronous adjustment) except for a generator is used. It plays the role of effectively controlling voltage / reactive power by selectively controlling phase machines, power capacitors, shunt reactors, etc.).

When a bus voltage is taken into the relay arithmetic processing unit, a plurality of buses are used together, for example, when the upper bus B1 and the second bus B2 are connected by a tie circuit breaker CBt as shown in FIG. Instrument transformer P on buses B1 and B2
T1 and PT2 are installed, and the secondary voltage thereof is input to the A / D converters AD1 and AD2 of the relay arithmetic processing unit RE. In the relay processing device RE, the introduction bus voltage is a healthy voltage or no voltage (for example, when the secondary rated voltage of the instrument transformer is 110V, the detected voltage is 0 to 70V in the phase voltage expression of the secondary voltage value). After determining whether the voltage range is set), the required relay calculation processing is performed and the operation of the adjustment relay is controlled based on the result. That is, the voltage / reactive power control is performed by the opening / closing operation of the switch for control equipment which responds to the relay output contact. FIG. 3 shows the procedure for selecting the introduced bus voltage at that time.

First, in step 31, the voltages of the instep and O-buses are detected, and based on the result, it is determined whether or not the instep bus has no voltage (32). If No, the bus voltage V used for calculation
Is used as the upper bus voltage (33), and the relay calculation process is performed using the voltage V (34). If Yes in the determination step (32), it is determined whether the O-bus is unvoltage (35). No
If so, the bus voltage V is set to the Otsu bus voltage (36), and relay calculation processing is performed (34). If the result of determination that there is no voltage on the O-bus is Yes (Yes), the relay is locked (37).

The above-mentioned non-voltage detection is performed based on the magnitude relationship of the positive bus voltage <ε and the second positive bus voltage <ε, which are obtained by obtaining the positive voltage from the three-phase input. Here, ε = 0
70 [V] (phase voltage expression of secondary voltage at PT installation point).

[0006]

As described above, if selection is made as the operation input depending on whether the positive phase voltage is within the set no-voltage range or not, the VQ device side has a fault and an incorrect voltage value is obtained. In case of, the voltage is used to perform arithmetic processing, which may result in inappropriate voltage / reactive power control.

For example, when the rated voltage (110 V) is applied between the secondary wires of the instrument transformer, the A / D
When the input of one phase is lost due to the failure of the converter, the positive phase voltage becomes 73.3V. That is, the voltage value exceeds the no-voltage range. Therefore, the relay arithmetic processing device RE uses the voltage to perform the relay arithmetic processing, and controls the adjustment relay with an erroneous arithmetic result.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above problems and to provide an introduction bus voltage selecting method in system control which can always take in an appropriate calculation input even if there is an internal failure.

[0009]

SUMMARY OF THE INVENTION The present invention takes in a bus voltage from a plurality of buses used together in a relay arithmetic processing unit for system control, and introduces one of the bus voltages as a representative input for system control. In the voltage selection method, a means for detecting an abnormality in the introduction circuit of each bus voltage is provided, and the presence or absence of an abnormality is determined in a specified order. When an abnormality occurs, the specified order is switched to the next highest bus voltage and the normal state is restored. It is characterized in that it is sometimes switched to return to the original bus voltage, which prevents a skeptical value from being input as a calculation when an internal failure occurs.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. First, in step 1, it is determined whether or not the voltage detection analog circuit on the upper bus side of the designated order (higher order) is defective.
For the means for detecting an abnormality, an automatic monitoring function used in a digital protection relay is applied. When the judgment in the judgment step 1 is No, the O-bus line switching flag is reset (2), and when the judgment is Yes, it is judged whether or not the upper bus voltage is being introduced (3). If the main bus voltage is being introduced (Yes), it is determined whether the voltage detection analog circuit on the O-bus side is defective (4). If the determination is No, the O-bus switching flag is set (5). ) Then, it is judged again whether or not the voltage detecting analog circuit on the upper bus side is defective (6). This is after the reset processing (2) of the Otobus switching flag, when the judgment (3) as to whether or not the main bus voltage is being introduced is No, and whether or not the analog circuit for voltage detection on the Otobus side is defective. The same applies when the determination (4) is Yes.

If the judgment (6) again as to whether or not the voltage detecting analog circuit on the upper bus side is defective is No, the upper bus voltage is selected as the calculation input voltage V (7), and this voltage V is used. The relay calculation is performed by using (8). If the result of the determination (6) again as to whether the analog circuit for detecting the voltage on the upper bus side is defective (Yes), it is determined whether the flag for switching the O-bus line is ON (9). If the determination is Yes, the O-bus voltage is selected as the voltage V of the operation input (10), and the relay operation is performed using the voltage V as in the case of selecting the instep bus (8). If No,
Lock the relay (11).

According to the above procedure, in the system in the state where the bus is also used, the relay operation is performed by introducing the instep bus voltage which is normally specified first. When the A / B bus analog circuit failure (zero-phase / reverse-phase monitoring failure, A / D converter accuracy failure, etc.) occurs, the A / B bus positive-phase voltage calculated by the relay arithmetic processing device becomes a suspicious value. For this reason, the introduced bus voltage is switched to the next-order O-bus voltage in the designated order in accordance with the abnormality detection, and the relay operation processing is performed using the O-bus voltage. However, when the detection analog circuit on the side of the upper bus returns to the normal state, the relay calculation input is switched to the voltage of the upper bus.

In other words, the analog circuit for voltage detection on the other bus side after the designated order becomes a backup existence,
At the time of failure recovery, it returns to the original state. Therefore, even if there is an internal failure, a proper bus voltage is always used as a relay calculation input, and system control such as voltage / reactive power control is appropriately performed.

[0014]

As described above, according to the present invention, when the system is in an operating state in which the bus is also used, even if a failure occurs in the analog circuit for voltage detection of one bus, the analog circuit of the other bus If it is sound, it becomes a backup existence, so that an appropriate voltage value can always be used as an input for relay calculation, and appropriate system control can be expected.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a single line connection diagram showing a configuration example of a circuit for introducing a bus voltage from a plurality of buses in a combined use state.

FIG. 3 is a flowchart showing a conventional example.

[Explanation of symbols]

 1 ... Judgment of whether or not the analog circuit on the upper bus side is defective 2 ... O-bus switching flag reset processing 3 ... Judgment whether or not the voltage of the upper bus is being introduced 4 ... Judgment whether or not the analog circuit on the O-bus side is defective 5 ... O-bus switching flag setting process 6 ... Judgment of whether or not the analog circuit on the K-bus side is defective 7 ... Process of setting relay calculation input voltage V as K-bus voltage 8 ... Relay calculation process using voltage V 9 ... O-bus switching flag Judgment as to whether or not it is ON 10 ... Process for setting relay operation input voltage V as Otobus voltage 11 ... Relay lock process

Claims (1)

[Claims] 1. In the introduction bus voltage selection method in system control in which bus voltages are respectively taken from a plurality of buses used together in a relay arithmetic processing unit for system control, and one of them is used as an arithmetic input, each bus voltage is selected. A means for detecting an abnormality in the introduction circuit of is provided, and it is determined whether or not there is an abnormality in a specified order, and when there is an abnormality, the specified order is switched to the next highest bus voltage,
In addition, the introduction bus voltage selection method in system control is characterized in that it is switched to return to the original bus voltage when it returns to a normal state.