Research On Self-healing And Optimization Control For Multi-source Active Distribution Network

The active distribution network(ADN) provides an effective solution to enable large-scale integration and utilization of renewable energy sources in times of low carbon economic development, which has a significant potential to support the realization of optimization and adjustment of energy structure in China. As a novel pattern for large-scale of distributed generations(DGs) plug to distribution network, which is different from the microgrid, ADN can coordinate control of diversified distributed resources including distributed generations, energy storage devices, controllable loads, demand side management etc, contributing to high penetration levels of new variable generation capacity and high utilization rate of distribution network assets. On the other hand, the ADN can actualize more advanced application of distribution automation, which choose both economic and reliable operation modes dynamically according to the changing external environment. In this paper, the selfhealing control strategy for multi-source active distribution network are studied as the following aspects:(1) An active reconfiguration strategy and preventive control system for active distribution network(ADN) considering maximum power supply capability(PSC) are proposed to solve the security problems caused by the increasing number of uncertainties in ADN. Firstly, a PSC index(PSCI) is proposed to evaluate the realtime security level of distribution network by sequential power flow algorithm with variable step size. Then, an active reconfiguration strategy with its preventive control system are proposed for pursuing the maximum PSCI and the minimum number of switch operations of distribution network when the PSCI is lower than a pre-defined warning value, which can significantly increase the reliability of distribution network.(2) A fast service restoration method to multi-source active distribution network with microgrids and electric vehicles is proposed based on the advantages of microgrids and electric vehicles in distribution network service restoration.Then,different optimal power flow(OPF) models for multi-level restoration strategy are constructed separately to minimize the network loss after service restoration.In addition,a genetic algorithm was introduced in the OPF of microgrid and electric vehicles restoration. The proposed control strategy can fully exploit and utilize the potential of microgrids and electric vehicles supporting the regional distribution network in case of emergency, which has a significant potential to improve the effectiveness,rapidity,economy and reliability of service restoration for multisource active distribution network.(3) A multi-level control strategy for transmission congestion is proposed based on the active reconfiguration and islanding capability from active distribution network. The multi-level control strategy includes an active reconfiguration scheme pursuing the minimum tie line power between the transmission and distribution network, an active islanding scheme based on the multi-source characteristic of active distribution network and a demand response scheme.