Modelling and Control of Microgrids in an Offgrid Operating Scenario: A Case Study

A system comprising of distributed energy resources, batteries, loads which are integrated and controlled like a single entity with confined electrical boundaries, often termed as microgrid, may operate in either grid tied or offgrid mode and provides efficient and flexible power flow. This feature ensures timely and effective response to load deviations and dispersed generating output, while maintaining stability and performance. Microgrid control solutions must be robust enough to run alongside and independently from the utility grid while maintaining power quality standards. The paper proposes a model of network forming inverter feeding a local load and operating independently of utility grid and its associated primary controls. Droop control, a well-known and easy-to model approach, is used to modify the frequency and voltage magnitude in relation to active and reactive power signals. A discretized SVM (space vector modulation) technique is utilized to convert modulating signals into pulses to drive the power electronics based inverter. Computer simulations on MATLAB Simulink software are performed to evaluate the efficacy of these approaches.