An optimal reactive power control scheme for rectifying station considering the coordination control of low-voltage reactor and AC system

摘要

When rectifier station of line-commutated converter based high-voltage direct transmission current has power fluctuations running at large load, reactive power compensator controlled in groups at rectifying station are switched frequently. That problem potentially has impact on service life of corresponding circuit breaker and threatens the safe operation of the DC system. In this study, in view of the characteristic of close connection between rectifier station and AC system, combined with the existing reactive power control scheme, in order to reduce the number of switching times of reactive power compensator, an optimal reactive power control scheme is proposed when rectifier station running at large load. When the converter station absorbs reactive power, the presented strategy takes converter bus voltage as the main control quantity with the starting point of taking full account of the reactive power support capacity of available generators near the station. When the converter station produces excess reactive power, the strategy takes the reactive power exchange of AC and DC system as the main control quantity, with the starting point of taking full account of reactive power absorption capacity of low-voltage reactor. The simulation results in power system analysis and synthesis program show the effectiveness of the proposed method.