Generation Shedding Capacity Optimization of Sending-End Power Grids with Multi-DC Asynchronous Outfeeds Considering Frequency Stability

Abstract

For the asynchronous interconnection system, the inertia of sending-end power grid drops sharply. Because of the severe high frequency problems caused by bipolar blocking of a HVDC transmission line, the traditional generation shedding strategy for dealing with the high frequency problems has some risks such as inaccurate shedding capacity (i.e. over- shedding or under-shedding) and lack of the rotational inertia after shedding. In order to solve the inadequacy of existing generation shedding schemes, we propose a generation shedding capacity optimization model for the sending-end grid with multi-DC asynchronous outfeeds considering the stability of system frequencies. The model comprehensively considers a variety of constraints, such as the frequency constraints, network power flow constraints, reserve constraints, and the constraints of generator-tripping capacity. By taking account of the adjustment performance and geographical distribution differences of various units in the sending-end grid, the TOPSIS method and the Superiority Chart are used to obtain the penalty factors of various units, and the optimal generation shedding scheme of the sending-end grid is determined for the bipolar blocking fault of a large-capacity HVDC transmission line with the goal to minimize the comprehensive cost of generator tripping. An improved IEEE RTS-79 test system is taken for case study, which has verified the effectiveness and the frequency adaptability of the proposed model.

Keywords

• asynchronous interconnection
• sending-end power grid
• generation shedding
• inertia
• dc transmission
• frequency stability