ABSTRACT
This work involves the investigation of Power Losses and voltage drops in Electric Power Transmission Network, using the Nigerian 330kV National Grid as a case study. The work carried out an in-depth study and analysis of power losses in the Nigerian 330kV network and proposed modifications to improve the efficiency, reliability, security and ensure good quality power for the citizenry.
The research methodology involved an overview of the existing state of the Nigerian power system, collection of various data relevant to the study and presentation of the data using Microsoft Access. Power (load) flow analysis using Gauss Siedel (GS) method in Matlab environment was employed to determine the voltages and power angles, real and reactive power at the various buses and hence the power losses. The network was further subjected to contingency analysis and simulation using Newton-Raphson method in Power World simulator environment to ascertain the various flow configurations among various possibilities and their effects on the network. Models were then developed to relate the power losses and voltage drops to the length of lines and loadings to guide future transmission network planning. The simulated result were analysed to determine the best location of loss minimization devices and then the effects of losses on the network and to consumers. Several case studies were performed leading to the proposed 330 kV Nigerian Transmission network that will ensure system efficiency, reliability and security.
The study revealed that the existing network cannot cope with contingencies leading to very low performance and even blackout at emergencies. The receiving end voltages at Kaduna, Kano, Jos and Gombe are 0.9pu, 0.76pu, 0.75pu and 0.66pu respectively as against the specified limit of ±5% (0.95 – 1.05). Also the Shiroro-Kaduna line recorded the highest line losses of 12.77MW in the network. The Egbin – Ikeja West Line was also overloaded up to 118% during contingency analysis. The energy loss for 2005 due to 330kV transmission lines alone was found to be 337.5 GWH amounting to over two billion, six hundred thousand naira. The proposed 330kV transmission network incorporated some additional lines to form more loops and introduce minimal compensation at Kano, Gombe and Jalingo. The proposed network meets the acceptable voltage limits of ±5% and reduces the real power losses by 45% in the transmission network. Apart from satisfying the technical consideration, it also reduces the environmental impact due to losses and the associated huge financial losses. When the proposed network is implemented, Power Holding Company of Nigeria (PHCN) would be able to save several billions of Naira which could help to finance the required investment within a short time and make profit of similar amount. Thus, it can be concluded that the proposed network arising from this research will ensure good power quality, higher efficiency, reliability and security in the Nigerian 330kV Transmission Grid.
