Research And Application Of The Longitudinal Compensation Device Based On The Fast Switch For A10kV Long Line

With the development of economy and the rapid growth of electricity load, power grid belonged to most remote areas of the country extend to areas without electricity. The power quality problems of110kV high voltage long lines and medium voltage distribution network have became increasingly prominent. These questions focused on the performance of insufficient power supply ability, low supply voltage and the high voltage fluctuation rate. These problems lead to the supply voltage of load side far beyond the quality standards set by the state and impact people’s production and life in many areas. Aiming at this problem, the grid urgently need to study and develop cost-effective, reliable and efficient technology to control existing problems of power shortage and voltage quality.In this paper, we install the longitudinal compensation device at the end of lOkV long lines to meet the power requirements for the purpose in order to improve the voltage and the transmission capacity of transmission lines, according to the objective situation in Linyi area, which has long supply line, rapid growing load and the limited investment in the power grid. This paper analyzed the advantages and disadvantages of conventional longitudinal compensation and controlled longitudinal compensation devices, and proposed a rapid switch type longitudinal compensation device combined with the development of switching technology. It is in order to solve the technical characteristics of the traditional longitudinal compensation device which is complex and low reliability. The device was applied in the field, after the operation and comparison, it is verified that the voltage of line terminal is increased. The details are as follows.(1) Analyed the theory and application of traditional longitudinal compensation device, which include the comparative analysis of research, application and effect of domestic and abroad. Focused on the advantages, disadvantages and applications of thyristor switched series capacitors and thyristor controlled series capacitors;(2) Studied a set of lOkV reactive longitudinal compensation device which is based on rapid switch switching. The series capacitor groups were installed at lOkV line to select the appropriate compensation depth according to voltage fluctuations.The voltage is controlled within the permissible rated range, while maximizing the capacity of transmission lines; When the short-circuit is occurred in the system,the short-circuit fault will be judged in3ms by’ short-circuit quick recognition system’ which is paralleled with the capacitor, and the signal will be sended quickly to the high-speed switch which is paralleled with the same capacitor. High-speed switch can operate fastly and short capacitors within in a power frequency cycle (15ms) to meet the protection of capacitors;(3)Studied the high-speed switch type longitudinal compensation device’s influence on transmission line protection;(4) Installed the longitudinal compensation device which is in a particular line of distribution network to test the effect of voltage boost.