Design of Earth Grid for A 132/33 Kv Substation: A Case Study

This paper presents the design of Earthing system for 132/33 KV substation and calculation of its necessary parameters. Successful operation of whole power system depends on an efficient and satisfactory performance of substations. Hence substations areconsidered as heart of power system. In any substation, a well-designed grounding system plays an important role. Since absence of safe and effective grounding system can result in mal-operation of control and protective devices, grounding system design deserves considerable attention for all the substations. Grounding system has to be safe as it is directly related with safety of persons working in the substation. Main purpose of this work is designing safe and cost effective grounding systems for EHV substations situated at such locations where soil of the substation site is not uniform. To get desired parameters such as touch and step voltage criteria for safety, grid resistance, earth resistance, maximum grid current, electrode size, minimum conductor size, maximum fault current level and resistivity of soil, standard equations are used in a design of earthing system by selecting the proper vertical electrode size, horizontal conductor size and soil resistivity the best choice of the project for safety purpose can be performed.[1] This paper mentions the calculation of the desired parameters of earthing for 132/33 kV substation. A case study is done at 132/33 kV substation Degaon at Solapur in Maharashtra state Transmission Co. Ltd