SU955325A2 - Device for collecting bus differential protection - Google Patents

Description

(54) DEVICE FOR DIFFERENTIAL PROTECTION

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The invention relates to electrical engineering and can be used for the differential protection of busbars of electric power systems of alternating current.

According to the main author. St. No. 626463, a device containing current-voltage transformer transformers for supply and feed connections, the output windings of which are connected in series and connected to the primary winding of an isolation transformer, is known to have a rectifying bridge connected to the secondary winding, a multi-shoulder rectifying bridge to which input terminals are also connected transducer output windings, operating and braking resistors and reacting organ 1.

The known device has insufficient reliability. This is due to the fact that it lacks control over the health of the output windings of the transducers and connecting wires between them, which are the elements of protection that are most susceptible to possible damage.

The purpose of the invention is to increase the reliability of the device for differential busbar protection. TIRED TRAINS

The goal is achieved by the fact that the device is equipped with two additional resistors, separately connected to the extreme terminals of the output windings of the transformer converters of the supply and supply connections, connected in series, and the signaling organ input is connected in parallel with the operating resistor.

Above FIG. 1 shows a diagram of the proposed device; in fig. 2 shows its circuit of a 10-place when the output windings of the converters of powered connections are broken.

The device contains current transformer transformers - voltage of power 1 and powered 2 connections, many 5 shoulder rectifying bridge 3, two additional resistors 4 and 5, separation transformer 6, rectifying bridge 7, brake 8 and working 9 resistors, reactive body 10 and The signaling authority 11 and the resistance 12 of the primary winding 2 ° C of the transformer 6.

The device works as follows.

Claims (1)

In normal operating conditions, the working (differential) signal is almost zero and the reacting protection body does not work. In external short-circuit (short-circuit) modes, a large unbalance voltage can be generated at the operating resistor. However, it is significantly less than the braking voltage, which prevents the response of the reacting organ. In the internal short-circuit modes. brake and working signal are equal in magnitude. The voltage arriving at the input of the reacting body causes it to operate, since the principle of monitoring the operability of the output windings of the converters is based on the use of information obtained from the output windings of the converters when the power system is working. In normal operating conditions of the power system and when the monitored protection elements are operational, the voltage on the primary and, therefore, secondary windings of the isolation transformer is practically non-existent and the signaling organ does not work. At breakage of the output windings of converters; for example, powered connections (point A in Fig. 1) at the terminals of the windings of the transformer 6 and, therefore, a signal appears at the output of the signaling organ. The magnitude of this signal in the specified case (Fig. 2) is determined by the total output voltage of the power supply converter Ui and the ratio of the resistance 12 of the primary winding of the isolation transformer and one of the additional resistors 5. The signaling authority 11 triggers and signals a break in the output windings of the converters. The setpoint of the triggering of the signaling authority must exceed the value in the normal operating mode of the maximum unbalance voltage caused by the nonidentity of the converters. Obviously, when the winding terminals are closed, any converter at the input of the signaling body will be distinguished by a voltage greater than the unbalance voltage allocated at its input in normal mode, and it can also be triggered. To prevent false triggering of protection in the external short-circuit mode. in case of breaks or closures of the windings of the converters, the signaling body should also block the operation of protection. It is advisable to select the setpoint in the response time of the signaling organ 0.5-2 in order to detun it from emergency modes in the power system with serviceable windings. It should be noted that the reacting authority will not falsely operate when the output windings of the transducers are broken, since the signal generated at the same time on the working resistor 9 depends on the ratio of the resistance of the resistor 5 and the resistance 12 of the winding of the transformer 6 and will be less than its trigger setting. In addition, the brake signal in this case exceeds the working one; on the braking resistor, the total output signal of the transducers is allocated, the output windings of which remain intact, and on the working resistor - only a part of this signal. Thus, the proposed protection device without significantly complicating its circuit allows monitoring the operability of the output windings of the converters and connecting wires between them when the protected power system is operating in normal operation. This increases the reliability of the security device, which is the positive effect of the invention. The invention The device for differential protection busbars on the author. St. No. 626463, characterized in that, in order to increase reliability, it is equipped with two additional resistors, separately connected to the extreme terminals of the output windings of the transformer converters of the supply and supply connections, respectively, and the signaling body, whose input is connected in parallel with the operating resistor. Sources of information taken into account during the examination 1. USSR author's certificate No. 626463, cl. H 02 H 3/28, 1978.