Optimal Operation of Isolated Microgrids Considering Frequency Constraints

Josep-Andreu Vidal-Clos,Cristian Chillón-Antón,Oriol Gomis-Bellmunt,Eduard Bullich-Massagué,Samuel Galceran-Arellano,Eduardo Prieto-Araujo,Mònica Aragüés-Peñalba,Guillem Vinyals-Canal

doi:10.3390/app9020223

Josep-Andreu Vidal-Clos, Cristian Chillón-Antón + Show 6 more

Open Access

https://doi.org/10.3390/app9020223

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Abstract

Isolated microgrids must be able to perform autonomous operation without external grid support. This leads to a challenge when non-dispatchable generators are installed because power imbalances can produce frequency excursions compromising the system operation. This paper addresses the optimal operation of PV–battery–diesel-based microgrids taking into account the frequency constraints. Particularly, a new stochastic optimization method to maximize the PV generation while ensuring the grid frequency limits is proposed. The optimization problem was formulated including a minimum frequency constraint, which was obtained from a dynamic study considering maximum load and photovoltaic power variations. Once the optimization problem was formulated, three complete days were simulated to verify the proper behavior. Finally, the system was validated in a laboratory-scaled microgrid.

Highlights

The integration of distributed generation requires the development of new concepts for active grid operation, where microgrids are the most promising one [1]
This study develops a multi agent energy management systems (EMS) for an isolated microgrid
An important observation is that, generally, the generation was greater than the load because the emulated inverters had power losses

Summary

Introduction

The integration of distributed generation requires the development of new concepts for active grid operation, where microgrids are the most promising one [1]. Microgrids can operate in grid connected as well as isolated modes [2,3]. The active power balance to maintain the grid frequency has become one of the main challenges. The integration of large amount of photovoltaic (PV) generation can further stress the power balance due to the lack of inertia and the fast power variations of the resource. One possible solution to avoid frequency deviations produced by PV power generation is its curtailment [4]. Frequency deviations can be limited by increasing the grid inertia, which can be achieved by connecting rotating machines [5]. The main drawback is that these solutions have and adverse effect on the operation cost

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Conclusion