Impact of Increasing Load on the Distribution Network with the addition of Electric Cooking Stoves in Nepali Context

Abstract

According to Nepal’s budget for fiscal year 2079/80, the government has planned to distribute electric cooking stoves (ECS) to each household. With the use of ECS on a large scale, the load on the distribution feeder will increase significantly, resulting in a reduced voltage level at buses, increased loading on the distribution transformer, and, in fact, increased current carried by the feeder conductor. The study focuses mainly on the loading of the distribution transformer (DT), the voltage level at the buses, and the ampacity of the feeder conductor. The study is carried out considering two feeders: the Jorpati feeder in Kathmandu district and the Malangwa feeder in Sarlahi district of Nepal. The impedance, current and power (ZIP) coefficients and load of the study area are estimated by the polynomial load modeling technique on a seasonal basis. The results show that after connecting ECS of different power ratings, the major impact is seen on the Jorpati feeder during the winter season. After incorporating 2000W ECS to each household in Jorpati feeder, there is overloading on 18 DTs and the existing dog conductor will not be able to handle the increasing load current demand. Thus, the optimal cable selection suggests that the existing feeder conductor must be upgraded to a wolf conductor. In order to upgrade the size of 18 DTs and the conductor to a wolf conductor, the utility should invest approximately one crore, seventy-five lakhs and after upgrading the system, use of ECS can be promoted in the Jorpati area. After incorporating 3000W and 4000W ECS, there is overloading on most of the DTs, low voltage levels at buses and the existing dog conductor will not be able to handle the increasing demand for load current. Thus, feeder reconfiguration would be required. Similarly, in the Malangwa feeder, the results show that after connecting ECS of different power ratings, the major impact is seen in the summer season. There is overloading on almost all DTs except the private DTs, low voltage levels at buses and the existing feeder conductor will not be able to handle the increasing load current requirement. Also, the power requirement will not be met by the existing 8MVA power transformer. Hence, Malangwa feeder needs restructuring