Modelling and Analysis of Power Losses in Transmission System of Pakistan: A Case Study of Matiari-Lahore VSC-HVDC Link

Electricity crises are gripping Pakistan day by day with scarcity of conventional resources, higher import bill and increased Transmission and Distribution (T&D) power losses. Apart from the first two challenges, averting T&D losses could greatly help the country to cope-up with the crises. The aggravated T&D losses in the system are mainly due to use of decades old system and the alone use of High Voltage AC Transmission (HVAC) technology for the transmission of electrical power. Such huge power losses in HVAC transmission system compels the country to consider other alternatives to transmit electrical power. One of such alternatives is the deployment of flexible alternating AC transmission system (FACTS) devices in the existing old HVAC transmission system, whereas the other one is emerging High Voltage DC (HVDC) transmission system which also seems to be a feasible alternative now. Pakistan has already undertaken initiative to establish its first bipolar 660KV Voltage Source Controlled HVDC link from Matiari-Lahore that evacuates 4000MW of power from southern region and transmits over the 886Km transmission line to the central load centers of the country. This study undertakes the comparative analysis of power losses in both HVAC and HVDC transmission systems by modelling both the systems using Power System Computer Aided Design Software (PSCAD) where the power transfer capability and transmission distance have been taken common in both the networks. The study results reveal that over 886Km and 2174MW of power transfer, HVAC system has power loss to 504.28MW which is around 23.2%, whereas HVDC system losses are 235.46MW which are around 10.8%. Thus, the comparative analysis depicts that HVDC has 268.88MW less power loss which is 12.4 % less than that of conventional HVAC system. It is concluded from this study that Pakistan's initiative to establish HVDC system is timely, and country should consider expanding HVDC system over HVAC system in near future to attain energy security.