Optimized hierarchical control for distributed generators in smart microgrids

Abstract

This work focuses on the development of an optimized control scheme for managing the power generated by heterogeneous distributed generators (DGs) and renewable energy sources (RESs)that constituting a smart microgrid. A microgrid is a distributed energy system that gathering a combination of renewable energy sources and distributed generators, as well as local loads. It can exchange power with the utility grid, and it can operate autonomously. The ideal use of a microgrid is to supply remote regions or locations that are unable to access the public grid. Moreover, utility operators become more interested in using microgrids for producing electricity due to their sustainability, reliability, and cost-effective. The DGs such as energy storage devices and diesel generators are dispatchable generations that can adjust their output power according to the load needs, whereas, the RESs such as wind turbines and photovoltaic panels are non-dispatchable generations which are used to exploit their maximum power. In this sense, we have proposed a solution based on the hierarchical approach that consists of three levels, inner, primary and secondary. This solution is able to control DGs in a hybrid microgrid for supplying continuously the local consumers without any interruption and for exchanging a smooth power with the utility grid while exploiting the maximum power from the renewables. The inner control is responsible to regulate the output voltage of each distributed generator which is based on cascaded control and Proportional-resonant controller. The primary control generates the reference voltage of the inner control which its principal role is to coordinate the distributed generators in a decentralized manner to share the active and the reactive power demand among them. The secondary control compensates the voltage deviation toward the nominal values as well as it synchronizes the microgrid voltage with the main grid for a smooth transition.