The virtual oscillator control (VOC) strategy, as a grid-forming controller, demonstrates substantial potential for application in weak grid scenarios. However, research on voltage support strategies for VOC during grid sag faults remains limited. This paper establishes an Andronov-Hopf VOC (AH-VOC) system with voltage-current dual-loop control, then systematically analyzes the principles of inverter-based voltage support at the point of common coupling (PCC) during grid sag faults. The relationship between voltage support effectiveness, grid impedance ratio, and system short-circuit ratio (SCR) is thoroughly investigated. Specifically for AHVOC, an optimal power distribution strategy and a modified voltage reference scheme are proposed to achieve precise power regulation and optimal voltage support under grid sag fault conditions. The effectiveness of the proposed control strategies is validated through MATLAB/Simulink simulations.

As the core equipment of DC power system interconnection and energy transmission, the improvement of DC solid state transformers’ performances has an extremely important impact on the development and application of DC power system. In this paper, a Partial-Power-Processing (PPP) LLC-DAB DC/DC converter with a bridge arm reusing rectifier is proposed for DC microgrids. The proposed converter topology can not only decrease the switching devices’ quantity, but also increase the control freedom of the converter and improve the light load efficiency. The operation principles, soft switching characteristics and power loss analysis of the designed converter are carried out. Finally, the feasibility of the proposed topology and the correctness of the theoretical analysis were verified by simulation results.

This article proposes a new type of flux modulation linear permanent magnet (FMLPM) generator with dual-sided modular primary and consequent-pole structure to fulfil the low-cost and large-scale deployment requirements of wave energy converter. The key parameters of the generator are optimized using finite element analysis and the Taguchi method to maximize the performance of the designed generator. By comparing with traditional FMLPM, it is demonstrated that the proposed generator has advantages in terms of cost and performance and is more suitable for large-scale deployment of wave energy converter.

This paper investigates the design of passivity-based control for LCL-filtered grid-connected inverter based on the port-controlled Hamiltonian with dissipation (PCHD) model. The interconnection matrix is changed from the original antisymmetric matrix to the upper triangular matrix with zero corner elements, which simplifies the design process. What’s more, to enhance the stability of the system, the combination of classic control theory and modern control theory is proposed to design the damping parameters of the controller. The main idea is to ensure the inverter output impedance is passive. The relationship between the controller parameters and the external interaction stability is compared. The simulation results are carried out to validate the effectiveness and robustness of the proposed approach.

In this paper, the single-stage Maximum Power Point Tracking (MPPT) control strategy for the Aalborg photovoltaic inverter is presented. Aalborg inverter has many advantages, such as high efficiency, wide range of input voltage, minimum voltage drop of the filtering inductors, etc. Nevertheless, it is essentially a “half-bridge” inverter with two input sources, where one source works in MPPT mode, the other is out of control. If without the reasonable parameter design and the proper control, the bus-voltage of this inverter may change greatly, resulting in the serious power oscillation around maximum power point and the reduction of the energy utilization of PV array. In this paper, the MPPT algorithm of two independent PV arrays is proposed, and then the relation between ripple ratio and dc-link capacitance is analyzed. An 110V/50Hz prototype has been constructed. Simulations and experiments show that the proposed control strategy has good steady-state and dynamic performances.