MINIMIZATION OF THE IMPACT OF THREE PHASE FAULTS ON THE VOLTAGE PROFILE OF THE NIGERIA 330KV TRANSMISSION NETWORK USING CAPACITOR COMMUTATED CONVERTER-BASED HIGH VOLTAGE DIRECT CURRENT (CCC-HVDC)

This research paper presents the minimization of the impact of three phase fault on the voltage profile of the Nigeria 330kV transmission network using Capacitor Commutated Converter-based High Voltage Direct Current (CCC-HVDC). Power system disturbances caused by loss of generation, switching actions, change in loads, and majorly faults lead to various degrees of voltage instabilities. The consequence of voltage instabilities in our Power networks can be severe. This is because it can lead to loss of loads, loss of generation and loss of generator synchronism, under-frequency, and ultimately, voltage collapse. Imbalance in the reactive power supplied and the reactive power absorbed by the system has been identified as the key cause of voltage instabilities on our networks. High Voltage Direct Current and Flexible AC Transmission System (FACTS) are new technologies that employ modern Power electronic techniques in controlling transmission system parameters. These devices are very fast, flexible, and effective in controlling active and reactive power independently. In this paper, Capacitor Commutated Converted-based High Voltage Direct Current (CCC-HVDC), was used to minimize the impact of three phase fault on the voltage profile of the 28-bus Nigerian 330kV network. The HVDC model and its neural network controller were developed in Simulink-Matlab, utilizing resources from Matlab and Simscape libraries. Transmission network data obtained from the Transmission Company of Nigerian (TCN) Osogbo and augmented with simulation data were used to train the ANN controllers. A performance training of 94% ensured that the neural network controllers produced the desired results. Result of simulations of the network models showed that CCC-HVDC minimized the impact of three phase fault on the voltage profile of the Nigerian network by enhancing the voltage profile of the network. CCC-HVDC improved the network's voltage profile by 97.5% without three phase faults. During a contingency of three phase faults, CCC-HVDC improved the network's voltage profile by 6.25%. It was concluded that CCC-HVDC controlled by neural network was effective in minimizing the impact of three phase fault when connected between the point of fault and the bus of interest. ANN controlled CCC-HVDC was able to achieve this by exploiting its capacity of simultaneously controlling active and reactive power in a network thereby boosting the voltage profile during fault situation