An Optimal Strategy Of Black-start Restoration In AC/DC Hybrid Transmission System

Since the complexity of HVDC transmission technology, its startup is always put at the late stage of black start-up of the power grid after the trunk networks has been recovered in order to ensure that the power system is stable. However, quick restoration of HVDC can play an active role on the whole power system restoration, so it is essential to study on the effect of HVDC in units restoration stage, network reconstruction stage and load restoration stage, and such problems as its operation control mode.In this paper, an optimal strategy of black-start restoration in AC/DC hybrid transmission system was studied. This paper analyzes the general process and principles of black-start, as well as issues related to black-start process that may arise, such as over-voltage, self-excitation and so on. The role of the HVDC project in the black-start and recovery process of Power Grid is explored. Furthermore, a scheme for the black-start of the HVDC project is studied, including the basic condition and startup mode.An optimal strategy of power system restoration is proposed to determine the optimal skeleton-network for reconfiguration and to optimize the sequence of restoration paths, which is based on evaluation method for node importance by weighted network modeling. With this strategy, both network topology of the power grid and distribution of electrical characteristics are considered. The important node evaluation indicator is proposed based on the weighted power network model. A network-reconfiguration efficiency index to consider outage costs of the important loads is proposed as the target of the reconfiguration optimization.The effectiveness of the proposed method was validated by the optimization results on the power system of Shanghai province. The PSD-BPA model of Shanghai power grid is used to analyze the reliability of the strategy of black-start restoration in AC/DC hybrid transmission system. The parameter calculation for determining the sources and paths is emphasized. A scheme for the black-start of Yidu- Huaxin ±500 kV HVDC project is studied, including the basic condition and startup mode. Finally, it is advised to add the proposed scheme into the actual Shanghai power grid black-start and system recovery precept.