Microgrid Management System Research Articles

Stochastic model predictive control for economic/environmental operation management of microgrids: An experimental case study

Microgrids are subsystems of the distribution grid which comprises generation capacities, storage devices and flexible loads, operating as a single controllable system either connected or isolated from the utility grid. In this work, microgrid management system is developed in a stochastic framework. It is seen as a constraint-based system that employs forecasts and stochastic techniques to manage microgrid operations. Uncertainties due to fluctuating demand and generation from renewable energy sources are taken into account and a two-stage stochastic programming approach is applied to efficiently optimize microgrid operations while satisfying a time-varying request and operation constraints. At the first stage, before the realizations of the random variables are known, a decision on the microgrid operations has to be made. At the second stage, after random variables outcomes become known, correction actions must be taken, which have a cost. The proposed approach aims at minimizing the expected cost of correction actions. Mathematically, the stochastic optimization problem is stated as a mixed-integer linear programming problem, which is solved in an efficient way by using commercial solvers. The stochastic problem is incorporated in a model predictive control scheme to further compensate the uncertainty through the feedback mechanism. A case study of a microgrid is employed to assess the performance of the on-line optimization-based control strategy and the simulation results are discussed. The method is applied to an experimental microgrid: experimental results show the feasibility and the effectiveness of the proposed approach.

Fuzzy logic based coordinated control of battery energy storage system and dispatchable distributed generation for microgrid

Microgrid is a good option to integrate renewable energy sources (RES) into power systems. In order to deal with the intermittent characteristics of the renewable energy based distributed generation (DG) units, a fuzzy-logic based coordinated control strategy of a battery energy storage system (BESS) and dispatchable DG units is proposed for the microgrid management system (MMS). In the proposed coordinated control strategy, the BESS is used to minimize active power exchange at the point of common coupling of the microgrid for grid-connected operation, and is used for frequency control for island operation. The efficiency of the proposed control strategy was tested by case studies using DIgSILENT/PowerFactroy.

Development of a smart micro-grid management system

The financial viability of the inclusion of a smart micro-grid monitoring and management system is presented in this paper. The smart micro-grid management system monitors distributed generation characteristics from various sources, and performs load curtailment and/or load deferral when and where possible to transfer energy use to periods of less expensive generation. A base case off-grid system using propane generators is presented and optimized to include renewable generation and battery storage. The smart micro-grid management system is then added to curtail and shift consumer loads to achieve energy efficiency and financial benefit to the system.

Study on Control Strategy of Microgrid in Islanded Operation Mode

The droop control strategy is only considered the frequency stability during the islanded operation mode of microgrid. So a cooperative control strategy based on two-layer hierarchical control structure is proposed in this paper. In islanded operation mode, Single master operation (SMO) or multi master operation (MMO) is decided by microgrid management system (MMS). When power changes during islanded operation, the master unit (s) with v/f control can balance the energy production and consumption quickly. Based on detecting instantaneous power of master unit (s),The secondary control of MMS sets renewed reference values of instantaneous power of slave unit (s) with PQ control. After that the output power of master unit (s) will return into zero. The simulation studies demonstrate that the proposed cooperative control strategy not only implements no-error frequency control and voltage stability control, but also provides enough spinning reserve margin for master unit (s) to keep the system energy balance all the time.

멀티에이전트 시스템을 이용한 마이크로그리드 분산 지능형 관리시스템 파일럿 플랜트 개발

This paper describes the development of the pilot plant of distributed intelligent management system for a microgrid. For optimal control and management of microgrids, intelligent agents area applied to the microgrid management system. Each agent includes intelligent algorithms to make decisions on behalf of the corresponding microgrid entity such as distributed generators, local loads, and so on. To this end, each agent has its own resources to evaluate the system conditions by collecting local information and also communicating with other agents. This paper presents key features of the data communication and management of the developed pilot plant such as the construction of mesh network using local wireless communication techniques, the autonomous agent coordination schemes using plug-and-play functions of agents and contract net protocol (CNP) for decision-making. The performance of the pilot plant and developed algorithms are verified via real-time microgrid test bench based on hardware-in-the-loop simulation systems.

Development of Hardware In-the-Loop Simulation System for Testing Operation and Control Functions of Microgrid

This paper proposes a hardware in-the-loop simulation (HILS) system as a new method to develop and test control algorithms and operation strategies for a microgrid. The HILS system is composed of a real-time digital simulator (RTDS) for real-time simulation of the microgrid, a prototype microgrid management system (MMS) under test, and a communication emulator for interface between the prototype MMS and the RTDS. The prototype MMS is designed to operate microsources of microgrid and to control power flow at the point of common coupling (PCC) in the grid-connected mode, and voltages and frequency in the islanded mode of the microgrid. The MMS is tested in the grid-connected mode and in the islanded mode, respectively, to show the validation of the proposed HILS system.

Cooperative Control Strategy of Energy Storage System and Microsources for Stabilizing the Microgrid during Islanded Operation

In this paper, the cooperative control strategy of microsources and the energy storage system (ESS) during islanded operation is presented and evaluated by a simulation and experiment. The ESS handles the frequency and the voltage as a primary control. And then, the secondary control in microgrid management system returns the current power output of the ESS into zero. The test results show that the proposed cooperative control strategy can regulate the frequency and the voltage, and the secondary control action can contribute to improve the control capability.

Performance Evaluation of Microgrid Management System by using a Hareware- In-Loop-Simulation Method

This paper presents a real time digital simulator based test system as a new method for testing microgrid management system (MMS). This system is composed of a real time digital simulator and a developed communication emulator. Real time digital simulator runs a simulation case for microgrid model and distributed generation source model. Communication module emulates communication functions of micro-sources in microgrid by transmitting the simulated signals to MMS. The MMS controls operation of micro-sources to control the power flow at the point of common coupling (PCC) and the voltage and frequency of microgrid. A prototype MMS was tested for stand-alone and grid-connected operation to verify the validation of the developed hardware-in-the-loop simulation (HILS) system.