Impacts in a Mini Grid by Micro Hydro Plants Interconnected with Grid: A Case Study of Taplejung Mini Grid, Taplejung, Nepal

Abstract

Electricity is essential for accelerating the economic development of any country and is also taken as an important input to improve quality of life. Small hydro power plants give more benefits to remote people special hills and mountainous region. Till 2018, more than 3000 MHPs totaling to 35 MW of power produced in our country. The price is NPR17-25 per Unit for Utility grid to supply in the remote location and 9-15 per unit via a 50-100 kW MHP that is tied to the large system. So, In Nepal, it is suitable for tied the running isolated mini grid and MHPs to the grid. In case study, a mini grid by MHPs connected grid of Taplejung, Province 1, Nepal consisting of MHP and rural electrification load is modeled. Load flow analysis for various cases of generation and connection are performed using ETAP software. There are six number of MHPs with installed capacity of 826 kW, around 2.2 MVA load in the system. The losses of the line in Grid is 206 kW, When mini grid and MHP plant is tied to Grid, then the losses of the system is reduced 6.2 kW. Similarly, % voltage drop of the line in Local Distribution Grid is 22% .As mini grid and MHP plant is connected to Grid, then the % voltage drop of the system is decreased to 0%. Likewise, the terminal voltage of the Grid is 333V. As mini grid and MHP plant is connected to Grid, then the terminal voltage of the system is increased to 399 V. The Overall system losses without DG installation is 6.2 kW, when DG of 250 kW is installed and losses in bus no 3 is found Lowest 1.4 kW and available voltage is highest 400 V. Hence above result shows that the loss of the overall system as well as % voltage drop of the system is reduced by significant level and the terminal voltage at various load point get improved which helps to find the quality of electric supply. The accurate location of DG is vital for minimizing losses and improving voltage profile, which indicates positive results on the overall economy. The large investment incurred in the distributed micro hydro generation can be realized in economic benefits.