Power Flow Equilibrium Enhancement on the Urban Power System by Unified Power Flow Controller

An isostatic power flow distribution benefits both the reliability and economy of power system operation. Therefore, the method of power flow equilibrium analysis and control is essential, especially for transmission sections between areas of the urban power system. This paper analyzes the power flow distribution of a coastal city over the South of China. To this end, an equilibrium index, called the variance of loading rate, is defined to quantify the static power flow distribution. Besides, the unified power flow controller (UPFC) is introduced to balance the power flow distribution, and the network adjustment is also considered. The modified IEEE 39 test system is studied based on the proposed unified solution algorithm, the results show that the power flow distribution, including transmission sections, areas, and system, becomes more isostatic after UPFC configuration with coordinated network adjustment.