Strengthening Plan of Sending-End AC Grid Considering DC Multi-stage Access

Strongly random renewable energy such as wind power and PV can achieve better consumption through HVDC transmission technology networking which is more flexible and environmentally friendly. However, blocking or commutation failure fault occurred in the convertor station brings great challenges to the sending-end AC gird with DC access, leading its security quality to descend. Based on this, an AC grid strengthening plan for multi-stage DC access is proposed which takes economy and security into consideration in this paper. Three strengthening plans include strengthening AC network, reducing DC transmission capacity and installing reactive power compensation devices are discussed. An economic model which takes the value of time and the different cost caused by different grid structures in each DC construction stage into consideration is established and used to choose the plan with the lowest cost. Based on IEEE 30 nodes test system, case studies demonstrate that the strengthening plan proposed can reduce the cost of each stage which based on improving the security quality of sending-end system. The effectiveness of this method is verified.