Abstract

A novel and flexible interconnecting framework for microgrids and corresponding energy management strategies are presented, in response to the situation of increasing renewable-energy penetration and the need to alleviate dependency on energy storage equipment. The key idea is to establish complementary energy exchange between adjacent microgrids through a multiport electrical energy router, according to the consideration that adjacent microgrids may differ substantially in terms of their patterns of energy production and consumption, which can be utilized to compensate for each other’s instant energy deficit. Based on multiport bidirectional voltage source converters (VSCs) and a shared direct current (DC) power line, the energy router serves as an energy hub, and enables flexible energy flow among the adjacent microgrids and the main grid. The analytical model is established for the whole system, including the energy router, the interconnected microgrids and the main grid. Various operational modes of the interconnected microgrids, facilitated by the energy router, are analyzed, and the corresponding control strategies are developed. Simulations are carried out on the Matlab/Simulink platform, and the results have demonstrated the validity and reliability of the idea for microgrid interconnection as well as the corresponding control strategies for flexible energy flow.

Highlights

  • Increasing amounts of distributed renewable energy sources (RESs), such as solar and wind, are expected to be integrated into the power system to meet the ever-growing energy demand, and more importantly, to meet the need to preserve fossil fuel resources

  • In which LΣ = LT + L0 is the equivalent inductance on the alternating current (AC) side of VSC0, LT is the equivalent inductance of the transformer, idi and iqi are the components of iabci in the d and q axes, ω i is the angular frequency of the AC system, edi and eqi are the components of eabci in the d and q axes, k is the transformer ratio, and sdi and sqi are the components of the switching function in the d and q axes of the dq rotating coordinate system

  • (2) for a microgrid working in the grid-connected mode, the voltage source converters (VSCs) beside the power grid must be in pattern 1; working in pattern 3; (3) for a microgrid working in the parallel mode, the corresponding control pattern of its VSC is determined according to the other microgrid’s operational mode

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Summary

Introduction

Increasing amounts of distributed renewable energy sources (RESs), such as solar and wind, are expected to be integrated into the power system to meet the ever-growing energy demand, and more importantly, to meet the need to preserve fossil fuel resources. Home-area network [23,24], by providing multiple functionalities: (1) working as a smart electrical interface, by enabling flexible, adjustable and bidirectional energy flow between the microgrid and the power grid [25,26]; (2) facilitating optimal energy management within the microgrid and improving the efficiency, reliability and economy of the system [22]; and (3) enabling wide-area data collection from various devices (including RESs, electric equipment and loads) in real time, and providing these data to the control center of the microgrid or to the main grid for load forecasting [27], operational status monitoring [28] and fault diagnosis [29,30]. Simulations are carried out on the Matlab/Simulink (R2014b, MathWorks, Natick, MA, USA) platform to demonstrate the validity and reliability of the presented interconnection framework and the corresponding energy control strategies

Energy Router-Based Interconnecting Framework for Microgrids
Schematic
Topology of the Energy Router
Topology and Mathematical Model of the Energy Router
Analytical Model of the Energy Router
Control Schematic of the VSCs
Control
Control Patterns for the Energy Router
Dual-Loop Feedback Control
Outer-Loop Controller
Simulation
Scenario 1
Scenario 2
Scenario 3
13. Simulation
Scenario
15. Simulation
Conclusions
Full Text
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