Comprehensive evaluation index based on droop control for DC distribution system dispatching

Abstract

This work proposes an index based on droop control to evaluate operating state of flexible DC distribution networks, which becomes the foundation of dispatch and control. And it provides a focus for solving the lack of effective evaluating methods for operations of networks. First, this paper introduces the principle of droop control and studies the operating characteristics of buses with droop control. Then, a comprehensive evaluation index is presented by analyzing the electrical network mechanism of flexible DC distribution networks by Thevenin theorem and involving the effects of droop control. The index represents a voltage error caused by the influence of variations of bus powers on bus voltages in the network. Hence, the expected dispatching power of the network can be obtained by the PI control of the index. In addition, according to the constraints of DC power flow and converter capacity, and the optimization objective of reducing network losses, power dispatching to each bus is calculated by the modified genetic algorithm (GA). Finally, a testing network and a physical experiment are employed to verify the practicability of the index and the effectiveness of the strategy. The proposed evaluation index can underlie forming the industry standard for the performance assessment of the DC distribution network.