Optimization of dynamic reactive power reserve in weakly interconnected or islanded HVDC sending systems

Due to severe geographical conditions, limited investment and environmental pressure, HVDC sending systems are often weakly interconnected with main network, Sometimes HVDC sending systems may even operate in islanded mode. Over-voltage/low-voltage after large disturbances becomes a serious problem. Static over-voltage/low-voltage problem in weakly interconnected or islanded HVDC sending systems is studied in this paper. An optimization method for dynamic reactive power reserve based on quasi-steady state sensitivity is proposed. Firstly, sensitivities of generator reactive power and bus voltage to reactive power disturbance are derived. Secondly, a method to calculate voltage variations with a sensitivity method considering HVDC transmission systems is put forward. Thirdly, system effective dynamic reactive power reserve is defined and deduced. Fourthly, an optimization model and process for dynamic reactive power reserve is come up with. Finally, the proposed algorithm is tested on a practical power grid. Simulation results demonstrate its effectiveness and feasibility.