RU2653514C1 - Method of disconnecting the controlled shunt reactor - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electrical engineering and can be used in electric power systems. In the method for shutting off the controlled shunt reactor, simultaneously with the signal for disconnecting the mains switch, a command is made to maintain a fixed predetermined current value. This excludes a trip with small currents, accompanied by overvoltages, and high currents leading to large losses.

EFFECT: technical result is increase in reliability.

1 cl, 2 dwg

Description

The proposal relates to electrical engineering and is used in electric power systems.

Widely known [1] is a method of disconnecting a controlled shunt reactor from the network, which consists in slowing down the current drop before shutting down. The hardware complexity of performing such an operation is a disadvantage of the method.

The closest in essence is [2] a method of disconnecting a controlled shunt reactor from the network, which consists in maintaining a predetermined current value and applying a signal to turn off the network switch. However, this method leads to overvoltages. As shown in [3, 4], when disconnecting small load currents (less than 25 A), large overvoltages can occur.

The technical result achieved in the proposed invention is to increase reliability.

The technical result is achieved due to the fact that at the same time they signal to maintain a fixed predetermined current value.

In FIG. 1 shows a diagram for implementing the method on the example of CSR with DC bias. It contains: 1 - CSR, 2 - power switch, 3 - high-voltage network, 4 - controlled rectifier, 5 - switching control unit, 6 - current sensor, 7 - voltage setting block, 8 - setting point selection unit, 9 - network voltage sensor 3, 10 - voltage regulator, 11 - current regulator. An example of the structure of block 8 is shown in FIG. 2 and contains: 12 - threshold element, 13, 14 - keys controlled by element 12.

The control method of CSR is as follows. CShR1 is made in a known manner and contains the power supply terminals of the rectifier 4. It is also possible the power supply of the rectifier 4 from an extraneous network. The switching control of the switch 2 is carried out by the control unit 5. In operating condition, switch 2 is turned on. Rectifier 4 is in operation and there is a direct current at its output, which goes to magnetize UShR1, which creates a magnetic field of magnetization in it. Proportional to this current and the current flowing from network 3 to UShR1. The regulator 10 acts on the rectifier 4 in order to maintain the required voltage level in the network 3, measured by the sensor 9. Block 8 connects the output of the voltage regulator 10 to the input of the rectifier 4 (key 14 of Fig. 2 is turned on), which includes its current control circuit, measured sensor 6.

If it is necessary to disconnect CShR1 from the network, a signal is sent from block 5 to switch 2. At the same time, a signal is sent to setpoint selection block 8, which, upon the appearance of this signal, disconnects the rectifier input from voltage regulator 10 and supplies a fixed setpoint signal to its input, setting the optimal current value when the switch 2 is turned off. At the same time, the threshold element 12 is triggered, the key 14 is turned off, and 13 is turned on (Fig. 2). The rectifier 4 is made quick-acting with a large magnification (10-25) of forcing and is capable of increasing the magnetization current of UShR1 from zero to nominal in a time of 0.1-0.2 seconds, thanks to the current regulator 11.

In the reactor-transformer CSR CSR, the performance is an order of magnitude higher. Typical tripping time of circuit breaker 2 (SF6) for tripping is 0.05 s, and taking into account the presence of intermediate protective relays is even longer. Therefore, at the time of breaking of the contacts of switch 2, at least 25-50% of the rated current of CShR1 will flow through them, if we assume that before that there was an idle mode. The range of rated currents of CSRs is usually 200-500 A. And the “safe” value of the current from the point of view of disconnection without overvoltage is about 100 A [3].

Thus, during the shutdown time, it will be possible to forcefully increase the current to the specified value and breaking the contacts at this current will reduce the overvoltage. In another case, when the current before applying the signal to turn off the switch 2 was close to the nominal, and a trip with such a current is undesirable due to prolonged arc burning and energy loss, the current will decrease to the specified value. This ensures reliable operation of the installation.

Information sources

1. RF patent No. 221302 class. Н02Р 6/12, 05.26.16.

2. RF patent No. 2473999.

3. www.forca.ru \ knig \ archivy \ electricheskaya-chast-electrostanciy-45.html.

4. The journal "Electro", 2016, No. 1, pp. 37-41.

Claims (1)

A method of disconnecting a controlled shunt reactor from the network, which consists in maintaining a predetermined current value and applying a signal to turn off the network switch, characterized in that at the same time a signal is supplied to maintain a fixed predetermined current value.

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