SU892555A1 - Device for advanced sectionizing of network - Google Patents

Description

(DEVICE FOR ADVANCED NETWORK SECTIONING

The invention relates to electrical engineering, namely, relay protection and automation of power systems, and can be used, for example, for adaptive automation of advanced network partitioning during short circuits with currents exceeding the breaking capacity of installed high-voltage circuit breakers. Prior sectioning devices are known in which the measurement organs are connected to the current of the sectional connection 1 or to the sum of the currents of several preselected connections of vi 2. One of the drawbacks of the known devices is that the current in the sectional connection and even the sum of the currents of several connections cannot be unambiguously determine the current of the damaged connection, as they depend on the operating modes of the generating sources, the network circuit and the short circuit location. The closest to the technical essence of the present invention is a device for centralized relay protection of a switchgear containing current sensors of all connections, switching blocks of input signals according to the number of connections connected to the outputs of current sensors, and output units 3J. The disadvantage of the device is that the advance sectioning is always carried out by the same switch regardless of the degree of short circuit current overload capacity of the switch of the damaged connections. This can lead to a significant redundancy in the leading disconnection of generating capacity and, in addition, to reduce the service life of the sectioning switch, since it ceases and shuts down during a short circuit on any connection of the power object with the requirement of automatic advance sectioning, the purpose of the invention is to reduce the redundancy when advancing partitioning and increase the service life of switches. This goal is achieved by the fact that a device containing current sensors of all connections is connected, a switching unit of input signals and a block of output organs, the outputs of which are connected to circuit breakers, are equipped with a selector switch, a mini selector, a setpoint automatic setting unit, an adder, a comparator and by the section selection circuit selector, we will take the outputs of current sensors of all n connections connected to the corresponding n inputs of the max detector and the automatic setting unit, and m of them according to the number of connections allocated for advance partitioning, are connected via the switching unit to the m inputs of the partitioning circuit selection unit and the mini selector, the output of which is connected to the first control input of the switching unit (m + t) input of the partitioning circuit selection unit and the first input of the comparator whose output is connected to the second control input of the switching unit and to (t + 2) the input of the section selection circuit selection unit whose m outputs are connected to the m inputs of the block of output switches off sectioning switches, and the second input is comparative The mouth is connected to the output of the adder, to the first input of which are connected (n + 1) the input of the automatic setting unit and the output of the max-selector, and the second input is connected to the output of the automatic setting unit of the setpoint. The drawing shows a block diagram of the proposed device. . The device contains switches 1, current sensors 2, switching unit 3 input signals, max-selector k, block 5 automatically setting a setpoint, .minisselektrr 6, block 7 of selecting a sectional circuit, comparator 8, adder E and block 10 of output organs, current sensors 2 can be performed, for example, with the prediction of the amplitude of the periodic component of the current at the beginning of the short circuit process to the possible saturation of the current transformers. A sampling of 5 .4 and storing of the values of the currents can be made after a short circuit by known methods. Switching unit 3 consists of m transistor switches controlled through comparators and triggers from mini selector 6 and comparator 8. Disconnecting the circuit from a mini selector 6 in block 3 with a signal equal to the signal from block 6 with no signal from the output of block 8. the disconnected circuit is excluded from the comparison in block 6, in block 5 of the atomatic setting, the circuit is selected that corresponds to the damaged connection, it is determined which group of switches (in terms of the breaking capacity, this circuit and Based on this, the output bias voltage output signal is automatically set at the second input of the adder 9B by block 7 for selecting the sectional connection according to the result of comparing signals from the inputs and output of the mini selector by separating the circuit with a signal equal to the signal from the output of block 6 and, if there is a signal from the output comparator 8, a signal is applied to the corresponding output organ of the block It). If it turns out that the circuits with the same signals are more than one, then a logical preference scheme is provided to ensure that only one of the sectioning switches is turned off. The device works as follows. In normal mode, signals from current sensors 2 are missing, so the signal from the mini selector 6 output to the first control input of switching unit 3 is equal to zero, and all m input circuits are connected to the inputs of mini selector 6 via the corresponding switches. is equal to zero, which excludes the possibility of: the operation of the block 7 for selecting the sectional attachment and the block of output organs 10. In a short circuit at one of the n Attachments with a current exceeding the breaking capacity of the switch, the output is max In selector 4, a voltage proportional to the current in the damaged connection is formed. This voltage is applied to the first input of the adder 9 and to the (n + l) input of the automatic setting unit 5. The latter determines which group the switch of the damaged connection belongs to and generates the corresponding setpoint voltage applied to the second input of the adder 9. Moreover the voltage from output 5 must have a sign opposite to the voltage sign from output k, so that in adder 9 the setpoint signal is subtracted from the maximum signal. The difference obtained at the output of the adder E corresponds to the fraction of the current through the switch of the faulty connection by which it exceeds the breaking capacity of this switch.

At the same time, signals from current sensors 2 of pre-selected m connections through the switching unit 3 are fed to the inputs of the mini selector 6 and to the corresponding inputs of the block 7 for selecting the sectioning connection prg1.

At the output of block 6, a signal is proportional to the minimum current from m connections. This signal is fed to the first control input of the switching unit 3 and to the first input of the comparator 8.

If the signal from block 6 exceeds the voltage from the adder E, then on. The output of the comparator 8 is a logical unit, prohibiting the disconnection of the minimum input circuit of the mini-selector 6 and allowing the operation of the section selection circuit selection unit 7, disabling the corresponding sectioning switch through the unit of output organs 10.

If the signal at the output of block 6 is less than the signal from the output of the adder 9, then the comparator 7 does not work, therefore the minimum circuit is disconnected in block 3 and the block 7 is disabled. After the minimum circuit is disconnected, the mini selector allocates a signal proportional to the current at the output with the minimum current from the remaining (t -1) connections.

The further process of passing the signals is similar to the one above.

After the partitioning switch is turned off, the breaker switch is turned off by its

protection. Then, the partition switch is turned on again from the recloser.

Since damage is disabled,

then the signals from the current sensors 2 become zero. The zero signal from the output of the mini selector 6 resets the circuit of the switching unit 3 to its initial state, thus ensuring the readiness of the device for repeated action.

The use of the proposed device makes it possible to reduce the redundancy at the advanced sectioning of the network by automatically selecting the optimal sectional connection and the current of the setpoint depending on the short circuit current and the breaking capacity of the switch on the damaged connection. The technical and economic effect from the use of the proposed device is achieved by increasing the stability of the power system, the reliability of the power supply to consumers and the service life of high voltage equipment.

Claims (3)

Invention Formula thirty A device for advanced network partitioning, containing current sensors of all n connections, a com- munication unit for input signals, and a block of output organs, whose outputs. connected with circuit breakers, characterized in that, in order to reduce the hinge (accuracy in advance sectioning and increase the service life of the switches, it is equipped with a max detector, a mini selector, an automatic setting unit, an adder, a comparator, and a sectioning circuit selector unit the outputs of the current sensors of all n connections are connected to the corresponding n inputs of the max-selector and the automatic setting unit, and m of them, according to the number of connections, allocated for leading seconds connected through the switching unit to the m inputs of the section selection circuit selection unit and the mini selector, the output of which is connected to the first control input of the switching unit, (m + l) input of the section selection circuit selection unit and the first input of the comparator, the output of which is connected to the second control to the input input of the commutation unit and k (t + 2) input of the section selection circuit selection block, to the m outputs of which are connected m inputs of the block of output organs of the sectionalizing circuit breakers, the second input of the comparator is connected to the output of Pa, to the first input of which are connected (n + 1) the input of the automatic setting unit of the settings and the output of the max-selector, and the second input is connected to the output of the automatic setting unit of the setting. Sources of information taken into account in the examination 1. USSR author's certificate number, cl. H 02 H 3/06, 1976. 2.Popov P.M., Nesterov N.V. Divider protection on reed switches. Electric power stations, 1975. i °. 3. USSR author's certificate number 663017, cl. H 02 H 7/22, H 02 H 3/06, 1977 (prototype). QDC 1 happy ui