SU1543496A1 - Device for automated central disconnection of load to preserve stability of power system - Google Patents

Abstract

The invention relates to emergency control in electric power systems and is intended to maintain the stability of parallel operation of generators of power plants and individual parts of power interconnections in post-accident conditions. The goal is to reduce excess load shedding. Consumers powered by lines 11 and 12 are disconnected using repeaters of the output relay of the shutdown receiver for any action of automation. The consumers feeding on lines 13 and 14 are turned off in the case when the power of consumers on lines 11 and 12 is less than what is required to be turned off in the event of an accident in the power system. The control of the total power of the consumers, which will be switched off during the operation of the automation, at any given moment is carried out using two power relays. The actuation power of the relay 20 must exceed, with a small margin, the return power of the second relay by the amount of power of the busiest line, the return power of the second relay is chosen equal to the load required to be turned off. Intermediate two-position relays and time relays provide an approximate constant power of consumers connected to automatics. 1 hp f-ly, 3 ill.

Description

(21) 4326800 / 24-07

(22) 10.08. (46) 02.15.90. Bul V 6

(71) North-West Branch of the All-Union State Design and Survey and Research Institute of Energy Systems and Electric Networks Zergosetproekt

(72) M.S. Israel (53) 621.316.925 (088.8)

(56) Actuators disconnecting loads from emergency control. Typical solution. No. 407-03-353.84, album 2, sheets 4 and 5, the Ural branch of the Institute of Energosetproekt, 1983.

Issues of emergency automation of power systems. Sat scientific papers of the in-ta Energoset- project, - Moscow: Energoizdat, 1982, p. 60-65, FIG. one.

(54) AUTOMATIC DEVICE OF CENTRALIZED LOAD CUT-OFF FOR SAVING THE STABILITY OF THE ENERGY SYSTEM

(57) The invention relates to emergency control in electric power systems and is intended to preserve the stability of parallel operation of generators of power stations and separate parts of power interconnections in post-accident conditions. The goal is to reduce excess load shedding. Consumers powered by lines 11 and 12 are disconnected using repeaters of the output relay of the shutdown receiver for any action of automation. The consumers feeding on lines 13 and 14 are turned off in the case when the power of consumers on lines 11 and 12 is less than what is required to be turned off in the event of an accident in the power system. Control

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The total power of the consumers, which will be turned off during the operation of the automation, is carried out at any given moment with the help of two power relays. The power of the first relay should exceed, with a small margin, the power of the second relay return by the amount of power. The invention relates to emergency control in electric power systems and is designed to maintain the stability of the parallel operation of the generators of power plants and individual parts of power combinations in the post-failure conditions. 20

The aim of the invention is to reduce excess load shedding.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - primary and secondary circuits of alternating current, and the voltage of the control organ of the current value of the load power; in fig. 3 chains of a constant operating current of the control body of the current value of the load power. thirty

The centralized load shedding automatic device contains a device for controlling action of automatic control dosage 1, which is located, as a rule, in the control room 35, the power supply system, device 2 for automatically memorizing dosages associated with device 1 of the configuration link, starting organs 3 located at the fixation points of alarms before and connected with the device 2 by emergency communication channels, devices 4 for disabling the on-load disconnect signals associated with the device 2 by the main communication channels, - 45 power devices 5 located in places where load shedding is required and 4 distribution channels connected to the device, current transformers 6, switches 7, bodies 8 controlling the current value of load power and maintaining the power of this power, voltage transformers 9 .

The loads 10 fed along lines 11 and 12 are switched off with the help of the output relays of the receiver of the shutdown of the unit 5 under any action of automation. Loads 10 feeding on line 55

over loaded line, the return power of the second relay is chosen equal to the load that needs to be switched off. Intermediate two-position relays and time relays provide an approximate constant power of consumers connected to automatics. 1 з.п, ф-л, 3 Il.

 50

50

5 about 45

five

m 13 and 1 are turned off in cases where the power of the load on the lines. 11 and 12 are less than what is required to be turned off in the event of a power outage.

The control of the total power of the loads, which will be disconnected by the action of automation, at any given moment is carried out by 8 group relays and 16 active powers connected to the organs, connected to current transformers 6 and voltage transformers 9 (Fig. 2). A relay 17 connected to a current transformer 6 at a common input of a power transformer 18 is used if it is necessary to vary the power of the disconnectable loads depending on the mode

power systems.

The loads are disconnected by the contacts 19 of the unit 5 (Fig. 3).

Intermediate relays 20 and 21, resistors 22-24 and capacitors 25 are connected to the relay contact circuits 15 and 16 and prevent them from burning and welding.

The contacts controlled by the relays 20 and 21 of the time relay 26-29 and the contacts controlled by the contacts of these time relays the on-off intermediate relays 30 and 31 provide an approximate power constant for the loads connected to the automatics.

Intermediate relays 32 and 33 with powerful contacts, such as the relay RL-342, switch to current transformer 6 circuits.

The actuation power of the relay 16 is taken to be greater than the return power of the relay 15 by an amount exceeding the maximum power of the most loaded line 13 or 14. The return power of the relay 15 is assumed to be equal to the load that must be shut off. If these conditions are not observed, the scheme can operate multiple times when the total power is 515

the loads without this line are less than the return power of the relay 15, and with this line it is more than the operation power of the relay 16.

In the output disconnection circuits of lines 11th to the loads, pointer relays and overlays 38-41 are used.

The device works as follows.

In the maximum load mode, only loads of lines 11 and 12 are connected to the automation.

As load decreases along lines 11 and 12, relay 15 returns, and consequently, relay 16, relays 20 and 21 return, and with time delay, relay 26 changes the position of relay 30, which prepares the trip circuit of switch 7 for line 13 and simultaneously with the help of a relay 32 connects the transformer 6 of the current of the line 13 to the current circuit of the power relay 15 and 16.

If the power on the three lines 11-13 in this case exceeds the actuation power of the relay 15, the relays 15 and 20 are triggered again and the device continues to pause. With a new decrease in total power (already three lines) and the return of relay 15, time relay 27 is started up, which, when activated, changes the position of relay 31, prepares the line disconnect circuit I, and its current transformer 6 is connected by relay contact 33 to current circuits relays 15 and 16.

If the subsequent change. In this mode, the total power of the four lines will exceed the response power of the relay 16, and therefore, 15, the contacts of the relay 20 and 21 trigger the relay 29, which, if activated, returns the relay 31 to its original position. In this case, the line disconnecting circuit AND opens, and its current transformer 6 is disconnected by contact of relay 33 from relay 15 and 16 current circuits, and relays 16 and 21 return. which, when activated, returns to the initial position of the relay 30, the disconnection circuit of the line 13 is opened and its current transformer 6 is disconnected from the current circuits of the relay 15 and 16.

Thus, the power of the loads connected to the chains of the emergency

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five

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automation, is constantly maintained in the interval between the return power of the relay 15 and the response power of the relay 16.

By adding intermediate relays and time relays, it is possible with the same two power relays to increase the number of lines to the loads controlled by the circuit.

In some cases, a different load power is required, which must be switched off during the same accident in the power system at its maximum and minimum modes of operation. This can be caused by an excess of reactive power in the minimum load mode in that part of the power system where power plants are located operating in the base part of the load curve, and a lack of reactive power in another part of the power system where power plants located in this mode are located. To change the power of disconnected loads depending on the power system mode, the circuit shown in FIG. 2, complements the power relay 17 on the common input from the transformer 18 and the contacts of this relay in the voltage winding circuits of the group power relays 15 and 16 changes the switching power of these group relays.

The proposed device makes it possible to prevent excessive load shedding while maintaining the stability of the power system at low cost when operating automation.

Claims (2)

1. The device for automatic centralized load disconnection to maintain the stability of the energy system. we, containing a control dosage unit, a dosage memory unit associated with a dosage unit by a tuning channel, triggering bodies associated with the dosage unit with emergency communication channels, non-critical and critical loads disabling signal distribution units associated with the unit memorization of dosages by the main communication channels, executive units connected with the distribution blocks of the load shedding signals by the distribution communication channels, and load current transformers, so that, in order to reduce excess load shedding, the executive bodies are supplemented by control bodies and maintain the current value of the power of the load to be shut off, each of which contains two power relays, the setting of one of them is equal to the value of the load to be switched off the control unit dosage unit, the setpoint of the other is greater than the setpoint of the first power relay by the amount of power of the most loaded of the disconnected lines, the intermediate two-position relays and the relay The currents included in the DC operating current circuits, while the current inputs of the two power relays are connected in series to the parallel-connected secondary windings of the current transformers of the loads, and to less responsible direct 18 77g-1 Mr I,., | 0 Of course, to the more responsible ones through the closing contacts of the intermediate relays, the power relay inputs are connected to the load voltage transformer, and the contacts of the output intermediate relays are connected between the actuators and the circuit breakers of the circuit breakers of more critical loads. 2. The device according to claim 1, characterized in that, in order to change the power of the disconnected load, it is supplemented with a third power relay installed on the common input of the substation, the closure contacts of which are connected in parallel with the windings of the voltage of both power relays installed in the total power measurement circuit disconnected loads, shunt part of the windings.