Hierarchical frequency control framework for a remote microgrid with pico hydel energy storage and wind turbine

An autonomous, sustainable microgrid with minimal operation and maintenance intervention would be a viable option to power the underprivileged remote communities in India. The microgrids supported by battery storage requires frequent maintenance and are prone to operational failures. So, the wind-powered agricultural pumping system is re-configured to form a hybrid microgrid with wind electric system (WES) and pico hydel energy storage (PHES) to meet the water and energy demands of the remote communities. As the frequency stability of autonomous microgrid is critical, a hierarchical frequency control framework is proposed in this paper. It has three different control aspects: firstly, novel droop augmented rapid power, and rapid speed control strategies are proposed for PHES. Secondly, the wind turbine is de-loaded by a dynamic droop integrated pitch angle controller to increase the inertial response of the system. Finally, a power management algorithm with suitable constraints is used to combine the control strategies of PHES and WES to derive the hierarchical frequency control framework. The effectiveness of the proposed framework is analysed through time-domain simulations using MATLAB/Simulink (R) by considering the change in wind speed, load, and the violation of water volume constraint. The proposed frequency control framework effectively managed the microgrid sources with suitable constraints and ensured minimal de-loading of the wind turbine. Furthermore, the framework also minimized the frequency nadir/peak and maintained the frequency within limits specified by the Indian Electricity Grid Code.

Automated summary

This paper investigates a hybrid microgrid composed of wind electric and pico hydel energy storage systems, proposing a hierarchical frequency control framework and analyzing its effectiveness through time-domain simulations. The framework effectively manages the energy sources of the microgrid, ensures minimal de-loading of the wind turbine, and maintains the frequency within the limits specified by the Indian Electricity Grid Code.