Aimed at the problem that the existing incentive pricing compensation mechanism cannot meet the differentiated needs of multiple types of load, a compensation method for interruptible load is proposed in the form of sectional compensatory price. Meanwhile, a two-dimensional alternating function of load transferable time and load transferable power is introduced to establish a transferable load compensation model to quantify the cost of load transfer. A model of multi-type demand response participating in the optimal operation of distribution network considering uncertainties in interruptible load is established. Aimed at the non-convex nonlinearity constraint of the model, it is transformed into a mixed integer second-order cone programming model by the second-order cone relaxation method, which is further solved by the CPLEX solver. In addition, the contribution degree and confidence degree are introduced to evaluate the user responsiveness. Simulation results show that the novel compensation mechanism can more reasonably guide users to adjust the power load, smooth the load curve, and improve the operating economy of distribution network.

To effectively reduce the inconsistency of series lithium-ion batteries in use, a novel equalization topology with the combination of a Cuk equalizer and a double-layer selector switch is proposed, which can quickly realize the energy transfer between any single cells and improve the equalization speed. According to the characteristics of the open circuit voltage (OCV)-state-of-charge (SOC) curve, piecewise equalization is adopted with voltage and SOC as equalization variables, and a fuzzy logic control (FLC) algorithm is designed to dynamically adjust the equalization current to reduce the equalization time and energy loss. Matlab/Simulink software is used to build a model and conduct simulations. Experimental results show that the energy transfer topology proposed in this paper saves of the equalization time by 22.17% compared with the traditional topology of energy transfer between adjacent cells of Cuk circuit. In addition, compared with the mean difference algorithm, the FLC algorithm improves the time efficiency by more than 30% and the energy efficiency by about 11% under static and charge-discharge conditions. Therefore, the feasibility of the proposed equalization scheme is verified.

A virtual synchronous generator (VSG) can provide inertia and damping for the grid connection of new energy by simulating the characteristics of a synchronous generator. However, a circuit breaking fault may occur in the process of high-frequency switching of power electronic switching devices, which will lead to a serious distortion of output current waveform and affect the safe and stable operation of power grid. In this paper, a VSG fault-tolerant model predictive control strategy based on neutral point voltage equalization is proposed to solve the fault problem of neutral point clamped (NPC) three-level VSG bridge arm. The operation mechanism of NPC three-level VSG single-phase bridge arm after fault is analyzed. The DC-side capacitor forms a virtual bridge arm after the switching device fault, which is reconstructed as a VSG bridge arm fault-tolerant structure. Under fault conditions, a current predictive model is established, and the space voltage vector in a fault state is reconstructed. The neutral point capacitor voltage on the DC-side is introduced into the cost function of fault-tolerant model to reduce capacitor voltage fluctuations and realize the fault-tolerant operation of VSG bridge arm. Experimental results show that the NPC three-level VSG can operate continuously after the switching device fault, which verifies the effectiveness of the proposed model predictive fault-tolerant control strategy and improves the operation reliability of VSG.

Multi-level converters are widely applied in DC microgrids because of their capability to reduce the voltage stress on switches and the volumes of filtering inductors and filtering capacitors. Since the flying-capacitance voltage and output voltage of a three-level Buck converter are coupled, the converter is a nonlinear system with strong coupling of multi-input and multi-output. To solve this problem, a decoupled backstepping sliding mode control method for inverse system is proposed in this paper. The inverse system method is used to decouple the output voltage control and flying-capacitance voltage control, and the backstepping sliding mode control method is used to ensure the stability and robustness of output voltage. The flying-capacitance voltage is balanced at 1/2 of the input voltage by the state feed-back control. Simulation and experimental results show that the proposed control strategy can achieve satisfying steady-state and dynamic characteristics of flying-capacitance voltage and output voltage.

The three-port converter studied in this paper includes three ports, i.e., power supply, energy storage and load, in which the load can directly obtain electric energy from the power supply or the energy storage port. First, a mathematical model of Euler-Lagrange form is established, a passivity-based controller is designed, and the simulation of passivity-based control (PBC) is carried out. The PBC strategy has advantages of strong global stability and strong robustness to system parameter deviation and external disturbance in the nonlinear system. Based on the PBC theory, the passivity of the three-port converter system is demonstrated. Through the PBC and single-phase-shift control of dual-active-bridge (DAB), the energy transfer between the three ports is realized. Finally, simulation results in Matlab/Simulink are given, which proves that the load in the device can directly obtain electric energy from the energy storage port and run safely, stably and reliably.

Aimed at the problems of current spikes and voltage fluctuations in the charging process of existing multi-level inverters, a novel quasi-resonant five-level inverter is proposed in this paper. A carrier-stacked pulse width modulation scheme is adopted, and the switched capacitor technology is combined with the traditional five-level inverter, which reduces the accumulated level at the previous stage and realizes the output of five-level voltage. In addition, the capacitor charging process and the series inductance resonate to eliminate current spikes and voltage fluctuations, while reducing the heating problem of the capacitor and prolonging the service life of the circuit. Finally, simulation verification is carried out, and results prove the correctness and feasibility of the scheme for the proposed inverter structure.

Aimed at the problem that the performance of dielectric barrier discharge (DBD) load cannot be fully utilized by the common load resonant-type power supply with continuous waveform and the deficiency that the topologies of existing pulsed power supplies are complicated, a power supply with unipolar forward pulse is proposed in this paper, which consists of one power switch, two diodes and one coupled inductor. Through the analysis of its working modes, it is shown that this power supply can provide a fast-rising pulse voltage for DBD load. In addition, the power switch operates in a soft-switching state. Simulation and experimental results verified the feasibility of the proposed power supply, indicating that it can provide certain reference for the upgrade of the existing power supplies for DBD load.

The two-switch Buck-Boost converter has been widely applied in step-up and step-down scenarios. However, it usually operates under hard switching conditions in the existing various control and modulation modes. In addition, its interleaved control circuit is usually complicated. A three-switch interleaved Buck-Boost circuit with co-directional coupling inductor and its control method are given based on the characteristics of co-directional coupling inductor. First, the coupling process of the coupling inductor during the switching process is analyzed under a large coupling coefficient, based on which the circuit's fundamental operating principle is given in detail. Then, it is concluded that the extended duty cycle and soft switching of Boost-side power switches can be achieved in the discontinuous self-induction current mode, so as to avoid the synchronous and current-sharing circuits in the two-phase interleaved control circuit, thus obviously simplifying the control circuit. Finally, simulation and experimental results verified the analysis results.

The hybrid energy storage system can effectively alleviate the frequency instability caused by the strong fluctuation and randomness of wind power output. In this paper, a hybrid energy storage system composed of batteries and super capacitors is taken as the research object, and a hybrid energy storage capacity allocation method is proposed. First, adaptive wavelet transform is adopted to perform a primary distribution of the wind power output, and the grid-connected power and energy storage power satisfying the requirements are obtained. Second, HHT transform is used to decompose the energy storage power, and a series of fluctuating power components and the instantaneous frequency of each component are obtained. Third, the cutoff frequency is determined according to the instantaneous frequency, the power components with a frequency higher than the cutoff frequency are allocated to super capacitors, and the rest are allocated to batteries. Finally, the rated capacity and rated power of the energy storage system are configured according to the energy storage power of batteries and super capacitors, respectively. Simulation results show that adaptive wavelet transform and HHT transform can effectively decompose the wind power output, thus realizing the stabilization of wind power output, as well as the capacity and power allocation of hybrid energy storage system.

Compared with 4G communication, 5G communication uses key technologies such as large-scale antennas, ultra-dense networking, and high-frequency communication to greatly improve its performance, resulting in increased power consumption of single 5G base stations and multiple sites. As a result, the power supply requirements are also changed. At present, there are two kinds of power supply forms which can meet the new power supply requirements, i.e., near supply and HVDC remote supply. Aimed at the HVDC remote supply, the power supply architecture and key technology are sorted out, and a feasible operation mode is proposed by comprehensively considering the operating investment cost in the economic mode of peak-shaving and valley-filling, the busy and idle periods of 5G base station service load, and the peak-valley time-of-use electricity price. On the basis of the construction which has already been invested under the HVDC remote supply scheme, the investment cost is small, and the economic benefit is obtained by using the time-of-use electricity price difference between peak and valley periods, thus reducing the power consumption cost of base stations to a certain degree. Finally, the development of 5G base station power supply is forecasted, providing reference for the research or design of its power supply.