Analysis of High Penetration Level of Distributed Generation at Medium Voltage Levels of Distribution Networks

Abstract

The high penetration of distributed generation (DG) including solar PV generation, small hydro generation and bio-energy into the distribution network area has changed the landscape of power systems. In a conventional power system, electricity is expected to flow from power plants, transmission systems and distribution networks, before being distributed to local consumers. However, the level of DG penetration in the distribution network, including by prosumers who install DG especially solar PV systems at their own premises, is increasing every year in many countries including Malaysia. Through the Net Energy Metering (NEM) scheme, prosumers can now export excess energy generated by DG into the grid. This trend is likely to continue driven by rapid advances in the power electronics sector and lower cost of ownership of solar PV systems. However, this trend may lead to several other positive and negative impacts on the distribution network. This paper investigates several impacts of high DG penetration levels on medium voltage (MV) levels of distribution networks including impacts on voltage profile, fault level, network losses, and line loading. Simulation analysis was performed using DIgSILENT PowerFactory software on substations in the MV distribution network. Several scenarios of increasing DG penetration level were simulated and the impacts on the distribution network were analyzed. The study also shows that the use of Volt- VAr Control (VVC) function in smart inverter (SI) is effective in improving voltage regulation in distribution network and implementation of fault current limiter (FCL) effectively mitigates the high fault level at distribution substation.