New Methods and Requirements for Planning of Medium Voltage Network Due to Distributed Generation

The subject of the paper is planning of distribution network in case of integration of distributed generation on weak medium voltage network. Because network long-term planning includes major uncertainties and integration of distributed generation has remarkable effects at these areas, final network plans may be done after the integration agreement has been concluded. In order to limit the price of integration fee the capability of existing network should be utilised as efficiently as possible. The existing planning methods of distribution network are designed for cases where a voltage drop limits the utilisation of the network. Because the proposed planning methods for a combined voltage drop and rise cases are based on the worst network conditions, the consideration of stochastic properties of production are not taken into account at all. The paper proposes two complementary planning methods for distribution networks including distributed generation. The conservative “minimum demand − maximum production” planning principle is extended to consider stochastic nature of distributed generation by using production curves. The main focus of the paper is on a comparison of proposed planning methods and on a testing of advantage voltage control to increase the network transfer capability. The studies are based on real life distribution network and load data.