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Optimal Placement of Synchronous Condensers for Voltage Stability of Large-scale Wind Power Transmission via HVDC system

High Voltage Direct Current (HVDC) is a prevalent option for long-distance transmission of large-scale wind power (WP), while voltage stability of the system is challenging. Synchronous condenser has advantages of larger capacity, stronger overload capacity and longer service life compared with conventional electronics based var compensation equipment to support voltage stability control. This article adopts an optimal placement of synchronous condensers at key nodes of large-scale WP system integrated to local Alternative Current (AC) system and transmitted by HVDC. Based on mathematically analyses of voltage stability of the system caused by local AC fault at the sending end, a multi-objective optimization model aiming at minimizing node voltage deviation and economic cost is presented. By considering equality and inequality constraints of the optimization model, Multi-Objective Particle Swarm Optimization (MOPSO) algorithm is adopted to optimize the distributed placement of the synchronous condensers coordinately. Finally, simulation results on a modified IEEE-39 node standard test system together with a 1100 kV HVDC verify that the proposed optimization method can guarantee the system voltage stability and improve economy effectively.