Research On Solid-State Compound Switch Applied In Substation Reactive Power Control Technology

Nowadays, in the demand of environmental protection and economy, power station and synchronous condenser in regional load centre decreasing in ratio, state grid is confronted with a problem lacking for support from dynamic reactive power source to voltage which brings about serious electricity quality problem. In order to improving power transmission ability, enhancing network’s security and reliability and maintaining stable operation of power system, it is necessary to strengthening the dynamic reactive power compensation ability.Reactive power and voltage regulatory measures are still machine-switched capacitor in the vast majority of districts in our country at present while SVC devices have been initially applied in some spots. The fatal defect of this kind of technology is large voltage oscillation and current shock in switched moment. It is not permissible to frequently operate.Solid-state compound switch technology based on solid-state transfer switch is applied in cut-off and put-in of capacitor is mainly issue studied in this paper. It is a new pattern zero-cross-switching appratus with no disturbance making use of high-power power electronic components. Operating principle of solid-state switch auxiliary switching technology is adding a controllable thyristor solid state switch in parallel in the substation reactive compensation equipment breaker gap to assist the existing breaker to switch. So the circuit breaker does not bear the impact of arcing in the switch process. The capacitive device to be controlled at the same time can achieve zero-cross-switching and does not withstand the impact of the switching process. In this manner, equipment is improved in it’s life span and can tolerate the frequent operations. The problem that reactive device is unable to frequently operate with the load continual changes can be solved.The technical product has been used in Chengdong110kV Substation of Handan. According to the site run-data, the solid-state composite switch can frequently and fast switch capacitor and is a good solution to the existing large number of voltage deviation and voltage fluctuations and have many advantages such as lower cost, smaller loss, higher reliability, small area covered.