Voltage security constrained reactive power optimization incorporating wind generation

This paper presents a comparative analysis between conventional optimal power flow (OPF) and voltage constrained OPF strategies with wind generation. The study has been performed using the New England 39 bus system with 12 doubly-fed induction generator (DFIG) based wind farms installed across the network. A voltage security assessment is carried out to determine the critical wind farms for voltage stability enhancement. The power losses and individual wind farm reactive power generation have been compared with and without voltage stability constraints imposed on the OPF simulation. It is shown that voltage constrained OPF leads to much greater active power losses in the network. Furthermore, the reactive power contribution of each wind farm is determined and a selective optimization completed to evaluate individual wind farm contributions towards system active power losses. Moreover, number of reactive power optimized wind farms can be reduced by only using those wind farms which contribute least to system active power losses. In addition, selective voltage constrained OPF can also be performed to minimize the adverse effect on system losses. Ultimately, the system operator should select the optimal wind farms for both voltage stability and loss minimization considering the trade-off between energy savings and voltage security.