Large-scale offshore wind energy integration by wind-thermal bundled power system: A case study of Yangxi, China

Abstract

A large-scale offshore wind power integration has a reverse peak regulation effect on the electric load and requires newly built transmission corridors. This work adopts a wind-thermal (WT) bundled system for offshore wind power integration and transmission line capacity factor improvement. The Qingzhou I-VII offshore wind farms (5000 MW) and the Yangxi coal-fired power plant units #5, #6 (2 × 1240 MW) are taken as a case study. The offshore wind farms (OWF) act as the must-take generator to increase the renewable fraction while the thermal power plants (TPP) provide peak regulation service to trace the changing net load. The OWF and TPP share the transmission line and point of interconnection. The OWF integration level is determined by the 8760-h production simulation and the wind-thermal (W-T) capacity ratio is 1.4516:1 (3600 MW OWF) in the studied site. The curtailment rate, electricity shortage rate, transmission line capacity factor (CF), load following precision, renewable fraction, CO2 emission of WT-W3600 condition are 9.02%, 5.41%, 61.36%, 91.43%, 50.46%, 6.97 million ton/year. There is a trade-off relationship between renewable fraction and curtailment rate in the WT system which restricts higher OWF integration. The demand-side response technologies such as power-to-X and energy storage are required to break the trade-off relation and reduce the electricity shortage rate. The WT system is economically viable and the net present value (NPV), levelized cost of electricity (LCOE), internal rate of return (IRR) of WT-W3600 are 3.55 billion¥, 0.4859¥/kWh, 4.82%. Co-locating the OWF and the floating solar photovoltaic (PV) is the future direction that benefits the intensive exploitation of sea area and offshore renewable energy development.