JPS6158123A - Method of testing equivalent of dc breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an equivalence test method for high voltage DC circuit breakers, and in particular,
This invention relates to an equivalent test method suitable for applying a DC high voltage to a test circuit breaker.

[Background of the invention]

Constructing test equipment comparable to that of a DC transmission system would require enormous costs. Therefore, developing a reliable equivalent test method by utilizing existing AC test equipment is an important issue in the development of DC circuit breakers.

FIG. 4 shows a configuration example of a DC circuit breaker installed in a part of a DC power transmission system. Direct current is supplied from the converter 1 through a DC reactor 2 including the line inductance and a commutation breaker 3. The illustrated DC circuit breaker includes a series circuit of a commutating circuit breaker 3, an oscillating current generating glue handle 4, a capacitor 5, and a closing device 6 in parallel, and a nonlinear resistor (hereinafter referred to as Z) containing zinc oxide.
(abbreviated as nO) are connected in parallel to form a separately excited vibration type DC breaker 20. FIG. 5 shows operating waveforms when the DC circuit breaker is disconnected. When the DC current is cut off due to a ground fault or the like, the commutation breaker 3 is opened and the electric charge previously charged in the capacitor 5 is transferred from the charger 6 to the time t! Insert it. An oscillating current of LC is superimposed on the DC Lg in the commutation breaker 3, the commutation breaker 3 is cut off at the current zero point at time t2, and Id* is commutated to the capacitor C. capacitor 5
Zn07 becomes conductive at time t3 when the charging voltage of Zn07 becomes high and reaches the system protection level (for example, 1.6 times the rated voltage), and the voltage between the poles of the commutation breaker 3 is limited by the limiting voltage of 2Ω07. A voltage close to direct current is applied. After time t4 when the Zn07 absorbs the energy of the DC reactor 2 and the ZnO7 current is cut off, the voltage returns to the current voltage. The energization time of Zn07 is influenced by the value of the DC reactor 2 including the line of the DC system, but the value of the DC reactor is generally large and difficult to simulate in an equivalence test. Therefore, in the equivalent test of the DC breaker 20, ZnO
A method of applying a voltage V waveform that simulates the current-limiting characteristics of No. 7 is being considered. (For example, Japanese Patent Publication No. 59-7945) [Object of the Invention] An object of the present invention is to provide a test method that employs an inductive DC equivalent test method and is capable of applying a reliable high voltage equivalent to that of an actual system. .

[Summary of the invention]

As a result of calculations and actual measurements, we investigated a method of limiting the overvoltage after current interruption with ZnO, separating it from the power supply side using an auxiliary circuit breaker, and applying a DC voltage equivalent to that of the actual system to the DC circuit breaker under test. The DC voltage applied to the test circuit breaker depends on the value of the ZnO limit voltage installed on the power supply side of the auxiliary circuit breaker and the test circuit breaker side, and it can be made equivalent to the actual system by adjusting the ratio of the limit voltages between the two. It was found that a certain voltage can be applied.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The present invention uses a short-circuit generator 8 and a protective circuit breaker 9 as power sources.
, closing switch 10. A step-up transformer 11 and a DC reactor 12 are provided.

The DC breaker 20 is on the right side of the auxiliary breaker 13 in the drawing. The ZnO 15 of the DC breaker 20 is arranged in the same manner as in the actual system, but the limiting voltage characteristics of ZnO itself are slightly different. This Z
By changing the limiting voltage ratio between oo and Zn014 provided on the power supply side of the auxiliary circuit breaker 13, it is possible to apply a DC voltage equivalent to that of the actual system.

FIG. 2 shows an example of operating waveforms, and the process up to the breaking process of the commutation breaker 3 is the same as FIG. 5. However, in the equivalence test,
When the auxiliary breaker 13 is added to the current carrying circuit, the auxiliary breaker 13 opens simultaneously with the commutation breaker 3. The current after being cut off by the commutation breaker 3 is commutated to the capacitor 5, and the voltage V between poles of the commutation breaker increases. At time t5 during this voltage rise, ZnO 14 starts conducting and limits the voltage between electrodes of commutation breaker 3. ZnO14 electric current, / increases, Zn
ZnO15 at time t3 when the voltage between the poles of the circuit breaker 3 increases due to the voltage and current characteristics (hereinafter abbreviated as VI characteristics) of O14.
begins to conduct. At this time, the '51 load charged in the capacitor from the power source is discharged through ZnO14 and ZnO15, so the direction of the current flowing through the auxiliary circuit breaker 13 is reversed, and the auxiliary circuit breaker 13 is at the current zero point. Cut off at t6.

After the auxiliary circuit breaker 13 is disconnected, the DC circuit breaker 20 is disconnected from the power supply, so the residual charge in the capacitor 5 is discharged through the ZnO 15, and the current limit circuit of ZNOIS is disconnected at time t4.

Therefore, the residual voltage of the capacitor at this point is applied to the DC breaker 20. The residual voltage of the capacitor 5 decreases due to the V-I characteristic of Zn015, but the current at this point is on the order of mA and the resistance value is high, so that an equivalent direct current with a long decay time constant can be applied. In the actual system, the power supply voltage returns to 1.0 PU after the current is cut off at ZnO, but in this equivalence test, the overvoltage equivalent to
times) is applied, resulting in a severe test. In the equivalence test, the goal is to apply a voltage such that the rate of voltage rise between the poles of the commutation breaker immediately after commutation is interrupted and the applied DC equivalent voltage V ae are equivalent to the actual system. In the case of this equivalence test, the target value of Vd changes depending on the limit voltage setting value of the ZnOs 14 and 15, and the target value of Vae cannot be applied. The cause is
Due to the size K of the heavy current flowing through the ZnO 15, an oscillating voltage is generated in the reactor 4 and capacitor 5, so this construction is not possible.

and the voltage peak value V between the poles of the commutation breaker 3.

As a result of examining the relationship between and the DC voltage Van, it was found that as ■ increases, V increases due to the V-1 characteristic of ZnO15, but Vd.

shows a decreasing tendency. Target vd.

Increasing the value of V to apply V is not desirable in terms of insulation, so it is desirable that the value of Vd be as close to V as possible. Therefore, it is necessary to reduce the value of ■. The value of (2) is related to the magnitude of the interrupting current Ias. Ids.

Keeping the value constant, the ratio N of ZnO14 and ZflO15 (Zn
It was found that when increasing the limiting voltage of O15/limiting voltage of ZnO, Ir decreased and the difference between ■ and ■-6 became smaller. That is, in the equivalence test according to the present invention, by increasing the limiting voltage of ZnO15 of the DC circuit breaker higher than the limiting voltage of ZnO14 on the power supply side of the auxiliary circuit breaker,
, the target is V6. can be applied. According to experimental and computational analysis results, N = 1
．． It was found that a value of about 1 is desirable.

FIG. 3 shows another implementation sequence. Auxiliary circuit breaker 13 is used when the auxiliary circuit breaker has a strict interrupting duty and cannot interrupt the circuit.
There is a method of reducing the breaking duty of the auxiliary circuit breaker by inserting a capacitor 16 between the poles of the auxiliary circuit breaker.

In this case, Zn0 that limits the voltage between poles of the auxiliary circuit breaker 13
17 are provided. If the limiting voltage of this Zn017 is low, the capacitor's
Since the residual charge of 9"5 is energized through ZnO17, the target v4.
cannot be applied.

Therefore, by setting the limiting voltage of Zn017 to be higher than the limiting voltage of ZnO14 and approximately the same as the limiting voltage of ZnO15, the target V4g can be applied.

〔Effect of the invention〕

As in the present invention, by setting the limiting voltage of ZnO between the poles of the auxiliary circuit breaker or the DC breaker under test to be higher than the limiting voltage of ZnO on the power supply side, reliable equivalent voltage equivalent to that of the actual system can be achieved. I can take the test.

[Brief explanation of drawings]

FIG. 1 is an equivalent test circuit diagram showing an embodiment according to the present invention;
2 is an explanatory diagram of FIG. 1, FIG. 3 is a circuit diagram showing another embodiment of the present invention, FIG. 4 is an actual system simulation circuit diagram, and FIG. 5 is an explanatory diagram of FIG. 1. 3... Commutation breaker, 4... Reactor, 5... Capacitor, 6... Closing switch, 12... DC reactor, 13-=Auxiliary circuit breaker, 14, 15.17-Zr
1O. 16... Capacitor.

Claims (1)

[Claims] 1. The auxiliary circuit breaker and the test circuit breaker are connected in series and voltage is applied from the power supply, and when interrupting, both circuit breakers are opened and the circuit breaker is connected to the power supply side of the auxiliary circuit breaker. In the inductive equivalent test method in which a high voltage is applied to the test circuit breaker through impedance elements provided on the test circuit breaker, the impedance value of the test circuit breaker is higher than that of the power supply side. Equivalent test method for DC circuit breakers. 2. Equivalent of the DC breaker according to claim 1, characterized in that the value of the impedance element provided between the poles of the auxiliary breaker is higher than the value of the impedance element on the power source side. Test method. 3. An equivalent testing method for a DC circuit breaker according to claim 1 or 2, characterized in that a nonlinear resistor whose main component is zinc oxide is used as the impedance element.