Expansion planning of transmission network with large wind farm in deregulated electricity market environment

The heuristic algorithm of conventional TNEP(Transmission Network Expansion Planning) is improved to meet the needs of grid-connected large-scale wind farm and deregulated electricity market.Monte Carlo simulation method is applied to deduce the PDF(Probability Density Function) of wind farm power output and the PDF of unit power outputs is determined according to electricity market swapping mechanism.The direct power flow model is adopted to analyze the PDF of line active power and the line overload probability.An effectiveness index considering both cost and profit prospect is put forward to evaluate the importance of line,based on which the TNEP is carried out.Simulative results for Garver 6-bus test system demonstrate the feasibility of the improved algorithm and the obvious effect of both deregulated electricity market and irregular wind power output on TNEP,probably resulting in the investment increase.