Analysis and Simulation of Nigeria Grid Dynamics Using Distributed Generator
Distributed Generators (DG or embedded generators) are generators that are connected to the distribution network of the power system. In this paper, the Nigeria 330kV grid network system was analyzed and simulated using the power system analysis tool (PSAT) simulation software to evaluate the impact of the distributed generator placement on stability of the 41 bus Nigeria grid Network System. The effect of the installation of the distributed generators on the grid was studied and analyzed and the result was compared with the grid, without the installation of the distributed generators. To achieve our aim, a load flow method using Newton-Raphson technique was used to estimate unknown variables in the network such as voltage, angle, MVar and MW on the power system analysis tool box simulation software (PSAT). Before the installation of the distributed generators, it was observed that the network was operating at an average voltage of 318kV and the total number of buses that were below the standard operating voltage range, (313.5kV-346.5kV), were about eleven buses. The total line loss in the network was at 107.23MW. A large-scale disturbance such as a three-phase fault was applied at Ajeokuta with the critical clearing time observed at 1.153 seconds for the fault to be cleared and the system returned to normalcy. When the relay acted due to the presence of the fault, it was observed that the oscillation of the rotor speed of the generator at Shiroro settled after 17.43 seconds. After the connection of the distributed generators on the network at the load buses below the standard operating voltage range, which are Kano, Katampe, Damaturu, Gwagwalada, Yola and B. Kebbi, it was observed that the average voltage of the entire bus in the network improved from 318kV to 326kV which is about 2.5% improvement. Even the violated buses were made to operate within the standard operating voltage range. There was the reduction in the transmission line loss from about 107.23MW to about 83.16MW which is about 22% reduction and the rotor speed of the generator at Shiroro was stabilizing after 16.9 seconds compared to the base case that took after 17.43 seconds. From the result obtained, it was observed that the installations of distributed generator in the Nigeria grid has the capacity to reduced line losses, voltage profile improvement in the grid and line flow reduction leading to the resolution of the congested network as well as improvement in power quality and stability across the grid network. It was also observed from the analysis that the distributed generator technology can be used to enhance the Nigeria grid system.