Distribution networks are currently changing from the classical paradigm based on passive grids transmitting power to supply final customers, to the smart grid paradigm integrating renewable distributed generators and active network management to achieve sustainability and higher efficiency and reliability. However, energy losses involve an important cost that should be minimized in every power system, especially in distribution grids, which may cause a negative impact on the efficiency of the system. For this reason, regulators have set targets to distribution companies in order to ensure a good quality of service to customers and also an acceptable level of energy losses. Additionally, explicit incentives have been also included to encourage distribution companies to consider the reduction of energy losses costs when planning and operating the network. Distributed Generation (DG) can reduce network losses if it is adequately managed and for low and medium penetration levels of this technology. Nevertheless, under a passive network management, DG may result in additional costs for distribution companies in terms of new required investment and additional energy losses. These effects are more significant with high DG penetration levels. Reference Network Models (RNM) are large-scale planning tools that can be used by regulators for assessing the impact of DG on distribution network losses at the different voltage levels: high (HV), medium (MV), and low (LV) voltage grids. RNM are able to build an efficient distribution network that aims to minimize the total costs (investment, operation and maintenance, and energy losses) while meeting prescribed reliability of supply targets in the different supply areas. For this reason, they are also a valuable tool for helping regulators in the task of designing incentive schemes for losses or quality of service. For instance, the Spanish Regulator is using these models to assess the efficient targets for energy losses in current distribution areas, comprising millions of customers. In this paper a methodology to assess the losses in the distribution network using a RNM is described. Then, the RNM is used to evaluate the impact of DG on distribution network losses. DG is modeled taking into account different capacity factors for each technology and load factors are also considered for customers at every voltage level. Four real size networks with different percentages of urban and rural areas are analyzed by varying the amount of installed capacity of DG. Finally, results of the impact of DG on network losses are presented.
Keywords: Distributed Generation, Distribution, Losses, Incentive Regulation, Reference Network Model.
Cigrè International Symposium on The Electric Power System of the Future: Integrating Supergrids and Microgrids. Bolonia, Italia.13-15 Septiembre 2011
Published: September 2011.