The grid-connected operation of an energy storage system is realized by a converter. Due to the low switching frequency of the conventional converter, there exists time delay in sampling and calculation, which will lead to poor transient characteristics of the energy storage system and even instability of the whole power grid. In this paper, model predictive control(MPC) is used to achieve a fast power response of energy storage system and avoid the influence of time delay. A power weight value function is introduced to calculate the optimal output voltage of energy storage converter in the MPC control of active and reactive power. To solve the problem of inaccurate MPC model caused by the parameter deviation of filter inductor, inductance error compensation control is used to improve the model accuracy. Through Matlab/Simulink simulations and experimental results, it is verified that the proposed scheme can improve the transient characteristics of energy storage system and effectively eliminate the influence of error on the MPC control performance.

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.

The state-of-charge (SOC) balance control of series-connected lithium batteries is of significance to the improvement of battery life. In this paper, a hybrid SOC equalization scheme based on active-passive equalization is proposed against the SOC discreteness of a lithium battery cell, in which the topology of the active equalizer is realized by a multi-winding flyback converter, and the passive equalizer consists of a resistor and a switch connected in parallel at both ends of the cell. The operating principle for the hybrid SOC equalizer is analyzed in detail, and the effect of SOC discreteness on equalization speed is discussed in terms of control strategy. The standard deviation representing the degree of discreteness and the coefficient representing the reasons of discreteness are introduced to realize the fast equalization of SOC under different discrete conditions. The topology of the proposed hybrid equalizer and the corresponding control scheme can optimize energy consumption and balancing speed, and experimental results verify the feasibility of theoretical analysis.

Aimed at the problem of DC voltage fluctuations caused by load switching, power fluctuations and dou-ble-frequency injection in DC microgrids, a dynamic compensation control strategy for a Buck-type bidirectional DC-DC converter based on model predictive control (MPC) is proposed. First, the corresponding discrete state space matrix is es-tablished, and the input current is used as the disturbance. Second, the model-based inner-loop current predictive control and outer-loop voltage control of the Buck-type bidirectional DC-DC converter is designed. Third, a dynamic compensa-tion control structure based on a residual generator is designed for the current disturbance, and the dynamic compensa-tion controller Q(z) is solved. At the same time, the recursive least squares algorithm is used for parameter identification to reduce the influence of model uncertainty on the dynamic compensation control strategy. Finally, a comparative ex-periment was designed on the PSCAD/EMTDC simulation platform to verify the effectiveness of the proposed control strategy. Experimental results show that the compensation control structure can effectively solve the problem of DC bus voltage fluctuations and enhance the robustness of the entire system without changing the original predictive control.

A design method for small and medium-power DC/DC converters suitable for low-orbit commercial aerospace is given in this paper. A synchronous rectifier flyback topology and surface mounted devices are adopted, which can meet the demands for common single-and multi-output DC/DC converters applied in aerospace, with advantages of low cost, high performance, high reliability, and mass production. To further improve the conversion efficiency and power density, gallium nitride(GaN) FETs are also used. In addition, the losses of main power devices in the topology under different operating conditions are calculated and compared. Finally, a DC/DC converter with a wide range of input voltage (23-47 V) and output of 5 V and 30 W was built for verification.

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.

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.

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.

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.

The optimal configuration of source-storage in micro energy grid(MEG) is a primary challenge at the early stage of its construction since there exist complicated energy flows. In addition, the uncertainties (especially the stochastic fluctuations of wind, solar, and multi-energy load power) in MEG are difficult to describe and overcome. To address these problems, the uncertainties of renewable energy and load demand are described as intervals, the minimization of annual converted investment cost is taken as the objective, and a linear AC power flow model is coupled. The constraints of cool/heat/electric power balance, node voltage static security, line capacity and heat pipe transmission power are taken into account, and the indeterministic constraints are transformed into deterministic ones based on the interval linear pro-gramming theory, thereby constructing an interval-based optimal planning model of MEG with the consideration of source-load uncertainties. The feasibility and superiority of this model are verified by case studies and analyses, indicat-ing that the planning scheme can adapt to different uncertain scenarios and ensure the system's stable operation.