Search

Unlike the typical microgrid with a common ac bus, networked microgrid always suffers more serious reactive power sharing issues due to its complex inner structure. In such case, the system reactive power sharing error cannot be easily evaluated and eliminated. So, this paper proposes a wireless control strategy that employs optimized virtual impedance controllers and local load measurements for the reactive power sharing in networked microgrid. First, from the modeling of microgrid network, an estimation method for network reactive power sharing error is derived. Through the estimation method-based network feature analyses, corresponding design for virtual impedance controller is presented. Then, by introducing genetic algorithm, virtual impedance controller parameters of each distributed generation unit are optimized, which aims to minimize the microgrid global reactive power sharing error. The parameter optimization process is performed offline in microgrid configuration stage. By using these optimized virtual impedance controllers, the reactive power sharing performance of a networked microgird can be greatly improved. Finally, the accuracy of the estimation method is validated by MATLAB simulation results, and the feasibility of the proposed virtual impedance optimization method is verified through real power experiments. [ABSTRACT FROM PUBLISHER]

To solve the reactive power sharing issue in droop control application, many solutions have been developed based on the basic wireless manner. However, existing wireless methods cannot eliminate reactive power sharing errors effectively, especially in load change situations. In this paper, a wireless reactive power sharing method that employs feeder current sensing and adaptive virtual impedance control is proposed for islanded microgrid. To improve reactive power sharing accuracy of virtual impedance method, an equivalent feeder concept is introduced, which can reflect the mismatch in connecting circuits equivalently. Through fast feeder current sensing, distributed generation units can calculate their respective equivalent feeders in real time. With the cooperation between real-time calculation and virtual impedance control, the proposed method achieves both accurate and fast performance in reactive power sharing. Compared with communication-based methods, the proposed wireless control provides the same high accuracy in reactive power sharing; meanwhile, its response speed to load change is much faster than that of other methods. Moreover, the proposed method can work as normal even though load changes during the transient process. Matlab simulation and real-time digital simulator test are used to validate the feasibility of this method. [ABSTRACT FROM AUTHOR]