For the conventional resistive active power filter (RAPF) based on impedance matching idea in transmission line theory, which aims to damp out background harmonic propagation on the distribution feeders. The so-called damping refers to the suppression of the existing harmonic propagation, but there is no ability to attenuate the source harmonic voltages along the feeder under all cases theoretically. This paper focuses on how to attenuate the source harmonic voltages along the feeder to achieve better performance. Not being based on the impedance matching idea, the proposed standing wave phase shifting active power filter (SWPS-APF) moves the phase of the harmonic voltage standing wave so that the antinode of standing wave closes to or exactly located at the beginning of the feeder to achieve harmonic attenuation. According to the relationship between the wavelength of the harmonics and the feeder length, the application range and the control parameters of standing wave shifting to the left and to the right strategy are discussed respectively. Finally, the correctness of the theoretical analysis and the effectiveness of the proposed scheme is verified by the simulations and experiments.

With the development of distributed renewable generations, a large number of distributed generations (DGs) are connected to the microgrid. Therefore, distributed cooperative algorithms are more suitable for optimal dispatch of the microgrid than centralized algorithms. This paper proposes a novel distributed cooperative control method for optimal dispatch of microgrids, considering line losses and time delay. First, the optimization model of the microgrid considering line losses is established, and optimality conditions are obtained. Second, a novel distributed optimization method considering line losses is proposed, where the primary control is to achieve optimal dispatch, and the secondary control is to achieve frequency regulation. Third, the stability of the system under time delay is analyzed, and the robust stability conditions are obtained. Finally, simulation results verify the the effectiveness of the proposed method.

This work presents an improved self-adaptive power distribution approach for the microgrid in five modes under different pandemic conditions in a typical tourism water village in Northern China. Differently from the other studies, this work concentrates on satisfying the specific power supply requirements under the COVID-19 background, with the maximum value of the composite index as the object function. Composite index includes not only the economic factors, but also some compulsive factors to ensure the requested power supply of the residents/tourists. The improved particle swarm optimization method which employs the modified weighted factor and the elite strategy is utilized to optimize the power dispatching of the microgrid. Moreover, the impact of the pandemic has been fully considered by comparing the power dispatching before and after the pandemic. The case study in Baiyangdian Region confirms the effectiveness of the proposed method. With this method, the optimal power dispatching is determined under different modes.