Development of utility interactive inverters for controlling renewable energy penetration into grid

Abstract

Micro grid consists of a cluster of distributed energy resources (DER) connected at the point of common coupling. Amount of renewable energy penetrated into the grid must be monitored and controlled for the stable and reliable operation of the grid. An efficient communication system interacts between DERS's and the utility substation is required to perform the task. DER inverters are capable of providing real and reactive power support according to the grid requirement. This paper discusses about an efficient control to economically allocate the available DER based on cost analysis. A supervisory price controller (SPC) and a Distributed Energy Resource Controller (DERC) provides the initiation signal to bidirectional voltage source inverter of the selected resource which is then responsible to provide real power support to the AC and DC loads connected to it. Apart from this service, the inverter using the control algorithm also provides reactive power compensation, current harmonics mitigation and load balancing so that the supply currents are always sinusoidal and at unity power factor. Instantaneous Symmetrical Component Theory (ISCT) is used to provide the inverter all these functionalities. The centralized operation of micro grid under varying energy price is demonstrated. A MATLAB/SIMULINK model has been developed and simulation results shows the effectiveness to provide active power and ancillary services according to changing prices due to the coordination between the participating micro resources.