Study On Virtual Power Plant Model For PV Integration In LV Network Of Pakistan

Pakistan is a developing country which unfortunately has been suffering from large power outages. These have hampered the growth of the country and have depleted the economy. Pakistan however is blessed with an abundance of solar energy. This solar energy needs to be integrated with the electrical grid. The decrease in cost globally in the cost of PV panels provides an opportunity from small scale consumers to produce their own energy to meet some portion of their energy demands. If these PV units can be integrated with the grid it will mean a decrease in cost for the small scale consumer because they will not have to invest capital in purchasing an energy storage system. However severe power outages provide a challenge, because during power outages the PV units will be need to be disconnected to ensure that islanding phenomena does not occur. Also there needs to be developed a control strategy that when there is no grid present the loads which are not necessary (for example water pumps) need to become disconnected from the grid so that unnecessary loading does not occur.The virtual power plant is an emerging concept which has the capability to allow geographically dispersed distributed generation sources to become integrated with the grid and while also allowing for the control of load operational timings. In this research a study is conducted on integrating PV units with the LV network in Pakistan by using a virtual power plant model. The virtual plant power plant model in this research consists of two tiers, tier one is central virtual power plant while tier two is local virtual power plant. The central virtual power plant is responsible for ensuring that the load shedding duration timings are transferred to the local virtual power plants, it is also responsible for disconnecting the loads which are not part of the virtual power plant contractual agreement. In this research these loads are modeled as fixed loads and it ensures that no reverse power flow occurs when the grid is not present. The local virtual power plant controls the operational timings of controllable loads. In this research there is one central virtual power plant and three local virtual power plants. Each local virtual power plant has different amount of installed load in it. A diesel generator is also modeled because the PV units are based on PQ control and require a voltage source to provide voltage and frequency support when the grid is not present. The low voltage network modeled in this thesis is part of the distribution network operated by Lahore Electric Power Supply Corporation. The LV networks modeled are radial in nature. The virtual power plant model is implemented using PSCAD. This virtual power plant model consists of photovoltaic units and diesel generator. The virtual power plant model is then simulated under different load shedding and photovoltaic penetration scenarios and it is analyzed that by adding the virtual power plant structure the reliability of the system increases. This increased reliability will result in increase in number of users of photovoltaic systems in Pakistan and hence helping in create a spiral effect which can result in increased investment in renewable energies in Pakistan. This research has been aimed at creating a study of PV integration in low voltage network using a virtual power plant structure and the results show that it has been successful in doing this.