Optimal allocation of distributed reactive power compensation for low voltage distribution network considering pump loads' characteristics

Aimed at the problem that voltage at the end of feeder lines is always too low to start up pump loads in low-voltage distribution network (LVDN) mainly composed of agriculture loads of oxygen pumps and water pumps, a distributed reactive power compensation optimal allocation model of LVDN including pump loads characteristics is proposed. In this model, the objective function includes both the investment cost of the compensation device and the economic benefits of reducing power loss of LVDN, and various constraints of LVDN in the condition of normal operation and startup of pump loads are included in the constraints. A sigmoid function is used to approximate the discontinuous sign function in the objective function, and a nonlinear penalty function which has relative large curvature near the discrete value is used to address the discrete variables characteristics of reactive power compensation capacity, then the primal-dual interior-point algorithm is used to solve the optimization model. Numerical results of an actual LVDN show that the obtained optimal allocation scheme of the method can improve the voltage quality of distribution network, ensure the normal startup of pump loads, and decrease the power loss of LVDN effectively.