Chun-xia Dou

Management and Control for Smart Microgrid Based on Hybrid Control Theory

Abstract The increased penetration of distributed generations introduces considerable complexity in the network operation, as well reliability if the distributed generations are effectively controlled and managed. Hence, the issues of management and control for smart microgrids become more significant. With respect to a large power system, a microgrid shows more conspicuous interactive hybrid dynamic behaviors. In this study, a novel hybrid model is first founded to clearly explain the hybrid interactive behaviors of microgrids. On the basis of the model, a two-level hierarchical hybrid control is proposed based on the hybrid system control theory in terms of interactive adjustment between the continuous controller at the lower level and discrete management at the upper level. The upper-level discrete management strategies are responsible for guaranteeing stability and security of the overall microgrid while constraining it to meet the load demand during significant disturbances, as well as minimizing the operating cost and reducing the emission during normal situations. The lower-level local continuous controllers are responsible for regulating the dynamic performance of each controlled unit to reach a satisfactory level. The effectiveness of the proposed hybrid control is demonstrated through simulation example.

Application of multi-agent technology in micro-grid system

This paper proposes a multi-agent technology to energy management of the distributed generations in a micro-grid system. An introduction and analysis of the distributed intelligent multi-agent technology are presented first, including its three-layered architecture and operation mechanism. Then, the objective function about micro-grid system is given. Control strategy of a multi-agent system and several common distributed generations are presented in detail with a framework containing some kinds of agents. Discussion about the multi-agent system and each agents behaviors are included. It demonstrates that the proposed multi-agent technology is successfully monitored, controlled and operated for the energy management of the distributed generations in micro-grid system.

An Integrated Phase to Ground Fault Protection for Neutral Compensated Power Networks

Single phase to ground fault in a neutral insulated or compensated power networks is difficult to be detected. In order to synthetically employing multiple available fault information, a D-S evidence theory based fault detecting fusion method is investigated for neutral compensated power networks. Three kinds of fault information as transient, abrupt wave and real power are employed for the purpose. Concept of fault measure is introduced to satisfy fusion description. And the corresponding fault measure algorithms for the three kind of fault information are constructed. Employing the investigated scenario, a fault detecting device was developed with virtual instrument. The device was tested in a power distribution network and has operated in field. Testing and operating results proved the presented scenario. By properly employing the multifold fault information, the detecting scenario is reliable and adaptive.

Hybrid control for micro-grid based on hybrid system theory

With the rapid increase in the rate of distributed generation ((DG) penetration depth, the issues of improving micro-grid transient become more significant. This paper investigates a two-level hierarchical hybrid control consists of continuous local controller for each DG unit at the first level coordinated by discrete supervisory control strategies at the secondary level for transients performance enhancement of micro-grid with various DG units following pre-planned or accidental switching events. The discrete supervisory control strategies are established based on information fusion technique by using wide-area measurements (WAM) in order to coordinate switching each DG subsystem into apposite operation mode following large disturbances. The continuous local controller for each DG unit is designed based on multiple Lyapunov stability theory incorporating linear matrix inequality (LMI) techniques in order to regulate the set point of each DG subsystem to reach the best performance and acceptable operation indexes. The effectiveness of the proposed hybrid control is demonstrated through simulation examples.