Technical Audit of Multan 500kV Grid Station

Commissioned in 1981, the station was upgraded to 500kV level in 1986 and has a transformation capacity of 900MVA. It serves as a main source of power for south Punjab, connecting to several grid stations through 500kV, 220kV, and 132kV circuits. The station's infrastructure includes two 450MVA-500/220kV autotransformer banks, three 160MVA-220/132kV autotransformers, and one 6.3MVA-132/11kV power transformer. The grid station is connected to Gatti 500kV GS, Yousafwala 500kV GS, Muzaffargarh 500kV GS, and Rousch power station through 500kV single circuit transmission lines, and to Guddu thermal power station through 500kV double circuit transmission lines. A technical audit of the Multan 500kV Grid Station was conducted by the USAID Energy Policy Program in January 2015. The audit team identified several key findings, including excessive loading of 220/132kV autotransformers, absence of circuit breakers and lightning arrestors on shunt reactors, and inoperative shunt reactors on certain circuits. Additionally, the audit revealed that major maintenance of several circuit breakers was pending due to unavailability of spare parts. The audit also highlighted the need for proper load flow studies to be conducted, taking into account the commissioning of the new 500kV D.G. Khan GS. Furthermore, the team recommended the installation of circuit breakers and lightning arrestors on shunt reactors, as well as the repair of inoperative shunt reactors. The audit also emphasized the importance of conducting C&DF tests of current transformers, potential transformers, and capacitor voltage transformers to ensure the healthiness of equipment. In terms of protection, the audit found that tele-protection facility was not available on four 500kV circuits and all 220 circuits, and that direct transfer trip facility was out of circuit in the 220kV system. The team recommended the installation of tie line protection on all 500kV and 220kV circuits, as well as the repair of inoperative protection relays. The audit also identified several discrepancies in the 220kV transmission circuits, including thermovision survey needs and clearance issues. The team recommended that these discrepancies be rectified to ensure system reliability and safety. Overall, the technical audit of the Multan 500kV Grid Station highlighted several key areas for improvement, including excessive loading of autotransformers, inoperative shunt reactors, and inadequate protection systems. The recommendations made by the audit team aim to address these issues and ensure the reliable and safe operation of the grid station.