The analysis of a rural distribution network with distributed generation in catchment area of Stara Planina

Abstract

The rural distribution network with 11 micro hydropower plants (MHPs) of 10 kWto 50 kW, in catchment area of Stara Planina, is analyzed in the paper. The network is characterized by: higher generation than consumption, outstanding variation of generated energy during a year, permanent increase of number of constructed and connected MHPs and significant space dispersion of MHPs. In such network the voltage deviations were appeared out of standard limits. After operation of MHPs during three years, their cost efficiency is analyzed and procedure of voltage regulation in the network is developed in the paper. The procedure includes calculation and setting of optimal off-voltage tap changer positions at transformers, twice in year, i.e. in season with higher generation and in season with lower generation. At outlying nodes (near outlying MHPs), where voltage was not regulated within standard limits (using this procedure), voltage regulation is performed by two autotransformers of 0.95/0.4 kV that are posted on posts of outlying nodes supply line. This procedure is proposed as a model which can be applied in future similar rural networks with MHPs that will be constructed in West Balkan countries after acceptance of EU directives about renewable energy sources. .