Author: V.K. Fokin, Research and development center at Federal Grid Company of Unified Energy System, JSC

Keywords: electromechanical AC link; short-circuit current; electrical machine.

Abstract: The article analyzes the experienceof using longitudinal capacitive compensation (CCP) devices used in AC networks with a voltage of 500 kV andhigher either independently or as part of fl exible AC power transmission lines. Such devices allow:

– signifi cantly increase the capacity of electrical connections to the required static and dynamic stability reserves;

– redistribute power fl ows along lines within sections between power systems, as well as between parallel lines in electric networks, ensuring acceptable and optimal line loading and reducinglosses of electric energy;

– normalize the voltage levels of the electrical network, especially if there are long-distance power lines;

– ensure effective damping of electromechanical oscillations between power systems; 

Foreign experience in the operation of the CPC testifi es that the greatest application is found for uncontrolled devices (NUPCs) and controllable ones (UPRK-B) with switching of vacuum or SF6 circuit breakers in 500 kV and higher networks, where a preselected correction of branch parameters is required to increase the capacity of the electrical system and optimal redistribution of fl ow. The article concludes that, in comparison with the UCPK-B, the thyristor devices of UPMK-TK are high-speed, but more expensivedevices. They can damp electromechanical fl uctuations between power systems and oscillations of the rotors of generators of electric stations operating on long-distance power lines far from the nodes of consumption. At the same time, feasibility studies should be made of the selection of USK-TC with other alternative options, for example, the use of transverse compensation devices (SC, STK, STATCOM, etc.).

Thyristor devices of smooth control of TCSC are universal most quickoprating devices performing the whole range of control. Being the most expensive, these devices enable to prevent and suppress capacitive self-excitation of electric machines, prevent the development of subsynchronous fl uctuations and torsional resonance. Choosing these devices requires special technical consideration and feasibility study.

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