Research of reactive power control strategy to reduce the reactive power exchange of AC and DC power grid

Abstract

In order to solve the difficulties of steady-state voltage regulating for ac power grid brought about by surplus reactive power during the small power running for dc project, the general practice is by adding station low reactor or static reactive power compensator to absorb surplus reactive power, or by adjusting the operation mode of ac/dc system to change converter consumption of reactive power, realising the balance of reactive power exchange. Via the detailed analysis and research of auxiliary converter reactive power control strategy (converter and low load reactive power optimisation function) based on different technical route of dc control system, deducing the relation between the converter reactive power consumption and α / γ , current, which show that increasing minimum γ can absorb surplus reactive power, effectively solving ac grid voltage rise during small power running. At the same time, engineering widely used for a low reactor or static reactive power compensator adopted in weak ac system with reactive power balance control strategy are discussed, putting forward the feasible suggestions of reactive power optimisation control strategy to reduce ac/dc power grid reactive power exchange. Experiments proved that the proposed method can effectively solve the surplus reactive power problem during dc low power operation, simplify the converter station reactive power configuration, can be applied in dc project, and has good applicability.