Impact of Location and Size of Solar PV Plants for Integration in the Lusaka distribution grid network

Abstract

Energy generation mix is an important area that could potentially have a significant impact on the Distribution network to address increase in system losses at distribution level, voltage drops and load growth. The distribution lines in Lusaka area are heavy-load lines with the highest demand density in Zambia. The Lusaka distribution line network system consists of a loop formed by interconnection of bulk supply points. Integration of energy generation mix into the existing Zesco power system has substantial impact on the system, with the power system losses and voltage profiles being the key issues. The impact of renewable energy in a generation mix has been investigated in this work. The project investigates the impact of location and size of solar PV plants for integration in the 33kV Lusaka Distribution network. The impact was assessed by examining the effect of solar PV plant on real power flow, system losses and voltage regulation in the 33kV distribution network. The loads, active and reactive power injections and network parameters were defined for the 33kV Lusaka distribution network and the load flow analysis for network was simulated using DIgSILENT Power Factory software to find the system losses, bus voltages and changes in power flow. The Global Positioning System was used to estimate the identified land availability and location of 13 feasible 33kV substations i.e. Chibombo, Chisamba, Fig tree, Chongwe 88/33kV, Avondale, Chalala, Katuba, L85, Makeni, Chawama, Chilanga, Mapepe, Chalala and Katuba. Based on the scope, the following 6 substations Makeni, Avondale, Chelstone, Chilanga and Mapepe, a comparative simulations impact analysis was undertaken for the progressive increase in the penetration level. The results show that at penetration levels up to 20% there was progressive reduction in bus power losses and progressive reduction in the voltage regulation. When penetration level goes beyond 21% bus losses starts to increase and above 50% penetration level there was change or reverse in power flow direction. The integration of renewable energy on the grid network shows reduction in active power losses and progressive improvement of the voltage regulation. It has also provided power locally to the substation load demand and reduces the power flow from the source.