SU1283893A1 - Device for linking two a.c.power systems - Google Patents

Abstract

This invention relates to the field of electrical engineering. The purpose of the invention is to improve the reliability of the power systems by providing communication functions in case of accidents and localizing disturbances within the disturbed power system. To achieve the goal, the parameters of the device, which contains two reversible converters connected in series through an inductive element, are chosen in accordance with the expression Cz 1 + Pc Etz, where Cc is the specified current overload ratio; Р - nominal transmitted power; Тц - time of emergency current shutdown by the main protection of the power system element having the longest delay; E „- the energy intensity of the inductive element. 1 il.

Description

0

11283893

The invention relates to electrical equipment, namely, to the creation of integrated power systems, and can be used to provide power flows from one part of the combination to another in normal and emergency modes without interfering with the electromechanical processes occurring in these systems.

The purpose of the invention is to increase the reliability of the power systems by ensuring the functioning of communication in case of accidents and localizing the disturbances within the disturbed power system.

The drawing shows a single line diagram of the proposed device.

Two power systems 1 and 2, depicted conventionally busbars 3, are connected by means of a power system communication device — a DC insert 4 containing two reversible converters 5 and 6 connected by alternating current to the said power systems and interconnected in series through inductive element 7 direct current outputs. The power system element is depicted as a busbar connection of the node substation protected by a relay protection kit 8 and a switch 9.

DC injection works as follows.

In the established nominal mode, the nominal power P is transmitted over the communication line at a voltage Uu and a current IM in a constant link

me

e ny n in

 and e mpln with m

m

 with

35 n

. with

20

25

current. With a significant excess of the time constant of the intersystem communication circuit over the duration of the disturbances in the systems being combined, we can neglect the active resistance of the communication and assume that

L

dl

(one)

de i is the current through the inductive element; t is time;

Ug is the voltage of the converter operating in the rectifier mode;

Uj is the voltage of the converter operating in the inverter mode;

Bn is the inductance of the inductive element.

In the steady-state nominal mode, the derivative of the current in (1) is zero, the current through the insert is unchanged, and the nominal power is transmitted via intersystem communication

Any disturbances in the interconnected power systems at given constant valve control angles directly reflect the difference in voltage across the expression (D. Although the insertion current cannot change noticeably

Due to the large inductance of the circuit, it is possible to maintain the parameters of the mode of each power system by adjusting the power flow in only one adjacent converter due to the energy stored in the inductive element, and not by changing the power flow from one power system to another. This simplifies the installation control system.

In case of disturbances of the type of short circuit in the AC network, the voltage of one of the two converters can be set to zero, the rate of change of the current is maximum and

according to (1) is tUK / bc. The most dangerous is a change towards an increase in current at full rated pre-emergency load. During the time of the TC disconnecting the damage by the relay protection kit 8

and switch 9 the intersystem communication current will increment

ul

 Ilil t

 L: H

(2)

and the maximum current value at the time of the accident shutdown will be

45

(3)

Prien in account that

(3) can

and expression like

h

rewrite

(I +

RnTi 2E

-).

(four)

EH

power consumption of th element.

inductively

The current overload factor, which is the ratio of maximum current to nominal current, is expressed as

g:

I U /

one

1 hL

VNIIPI Order 7454/54 Circulation 19

Random polygons pr-tie, Uzhgorod, st. Project, 4

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Claims (1)

Formula of the invention n. A device for communicating two AC power systems, each of which includes elements,. Equipped with a relay protection comprising two reversible converters connected in series through an inductive element, characterized in that, in order to increase the reliability of the power systems by ensuring the functioning of the communication in case of accidents and localizing disturbances within the disturbed power system, the device parameters are selected in accordance with the expression K, 5H RnTi 2En where Kc is the specified current overload ratio; R. - nominal transferable P power; T „is the time of disconnection of the emergency current by the main protection of the power system element having the highest aaaaaaaaaaing; E „- the energy intensity of the inductive element. g: I U / one 1 hL VNIIPI Order 7454/54 Circulation 19 Random polygons pr-tie, Uzhgorod, st. Project, 4 Subscription