Active Synchronizing Control of a Microgrid

Abstract

A microgrid is an aggregation of multiple distributed generators (DGs), such as renewable energy sources, conventional generators, and energy storage systems that provide both electric power and thermal energy. Typically, a microgrid operates in parallel with the main grid. However, there are cases in which a microgrid operates in an islanded mode, or in a disconnected state. Islanded microgrid can change its operational mode to gridconnected operation by reconnection to the grid, which is referred to as synchronization. Generally, a single machine simply synchronizes with the grid using a synchronizer. However, the synchronization of microgrids that operate with multiple DGs and loads cannot be controlled by a traditional synchronizer. It is needed to control multiple generators and energy storage systems in a coordinated way for the microgrid synchronization. This is not a simple problem, considering that a microgrid consists of various power electronics-based DGs as well as alternator-based generators that produce power together. This paper proposes an active synchronizing control scheme that adopts the network-based coordinated control of multiple DGs. From the simulation results using Simulink dynamic models, it is shown that the scheme provides the microgrid with a deterministic and reliable reconnection to the grid. The proposed method is verified by using the test cases with the experimental setup of a practical microgrid pilot plant.Index Terms-Energy storage system, microgrid, microgrid central controller (MCC), network-based control, static transfer switch (STS), synchronization.

Optimized energy management system to reduce fuel consumption in remote military microgrids

“…If one of the two diesel generators can be used as a backup power to improve the reliability, no synchronization between the two gensets is required, at this stage [13].…”

Static Switch Controller Based on Artificial Neural Network in Micro-Grid Systems

“…5 is used in this study [17]. MATLAB software for implementation of the proposed protection method is employed.…”

“…5, the micro-grid is a 380 V distribution feeder connected to the 22.9 KV distribution grid through transformer and static switch. The system consists of two diesel generators (DG1 and DG2), one photovoltaic cell (PV), a wind turbine (WT), four loads, three short distribution lines, and a static switch (SS or STS) [17]. DG1 and DG2, wind turbine and PV cells are modeled based on [18,17] and [20] respectively.…”

Control strategy for seamless transition from islanded to interconnected operation mode of microgrids

“…In general, a smooth connection is achieved when the voltages of the systems to be connected coincide in magnitude, phase and the frequency. In microgrid applications, synchronization before reconnection is usually accomplished by detecting the voltage magnitude, phase and frequency difference between the main grid and the microgrid [3,4].…”

“…The presence of many voltage source converters, however, may deteriorate its effectiveness. Reference [4] proposes an active synchronizing control scheme that also adopts a central based coordinated control for multiple DGs. In [5], the synchronization control system sends remote compensator signals from the substation to the speed and voltage regulators of a hydro plant, achieving safe reconnection.…”