Feeder flow control and operation in large scale photovoltaic power plants and microgrids : Part I Feeder ow control in large scale photovoltaic power plants : Part II Multi-microgrids and optimal feeder ow operation of microgrids

Abstract

This thesis deals with the integration of photovoltaic energy into the electrical grid. For this purpose, two main approaches can be identified: the interconnection of large scale photovoltaic power plants with the transmission network, and the interconnection of small and medium-scale photovoltaic installations with the distribution network. The first part of the thesis is focussed on the interconnection of large scale photovoltaic power plants. Large scale photovoltaic power plants are required to provide different ancillary services to the electrical networks. For this purpose, it is necessary to control the active and reactive power injected by photovoltaic power plants at the point of interconnection, i.e. to control the power flow through the main feeder. In this direction, it is developed a central controller capable of coordinating the different devices of the photovoltaic power plants as photovoltaic inverters, FACTS, capacitor banks and storage. The second part is focused on the distributed generation, consisting on small and medium-scale generation facilities connected to the distribution system. In this context, distribution grids, traditionally operated as passive systems, become active operated systems. In this part, the microgrid concept is analysed, which is one of the most promising solutions to manage, in a coordinated manner, the different distributed energy resources. Taking into account the possible transformation of the current distribution system to a multi-microgrid based system, the different architectures enabling microgrids interconnections are analysed. For the multi-microgrid operation, it could result interesting that a portion of their networks operate so that the power exchange is maintained constant, i.e. controlling the power flow at the main feeder. In this thesis, an optimal power flow problem formulation for managing the distributed generation of these feeder flow controlled microgrids is proposed.