Policy Review of Voltage Stability with High Penetration of Distributed Generation

With global acceptance of renewable energy and the deregulation of the energy sector as the future of electricity supply, policies are being formulated to increase the penetration levels of Distributed Generation (DG) in power systems. This new revolution may lead to a situation where the centralized power generators which are utilized for voltage control in traditional power system will be displaced by DGs which are not allowed to partake in Volt/Var control. Furthermore, reverse power flow associated with DGs will have an impact on the performance of voltage regulation devices. Lastly, the active power output variability of these DGs (mostly wind and solar) can impact negatively on the voltage stability. While IEEE standard (std) 1547 which regulates the interconnection of DG to the grid does not permit DGs to take part in voltage control of power system, the same can be said of IEEE std. 929 which focus on Photo-Voltaic systems. The result of this is excessive reactive power being made on the transmission network. This can affect the voltage stability of the network which can eventually lead to voltage collapse. To secure the future of our grid, the grid code and design of distribution network needs to be re-assessed.