When multiple energy storage units are connected to an energy storage station by the power electronic converter，the interaction and coupling effect bring challenges to the stable operation of the system. The small-signal model of the parallel storage system was established. The stability analysis was carried out based on the dominant modes and participating factors of the system. According to the relationship between DC bus voltage and current，a new rule was found：when the load power was constant，the increase in the number of power stations will produce an impedance multiplier effect，which can improve the system stability margin. Moreover，the improved participation factor method was proposed to verify the regularity of the effect. Finally，the experimental results verify the correctness of the above analysis.

Despite bringing several benefits to modern power systems，distributed generation（DG） and microgrids cause a significant impact on the operation of power distribution networks，especially with regard to the protection system. In this new scenario，the adoption of smart protection systems capable of incorporating advanced control and protection mechanisms is of paramount importance for ensuring the automatic reconfiguration and restoration of the power grid when undesirable phenomena like faults occur. Considering this scenario，a novel metaheuristic called adaptive fuzzy directional bat algorithm（AFDBA）was proposed，which can calculate the optimal setting of directional overcurrent relays（DOCRs）in the power grid without the need for tuning the initial parameters. The technique was applied to two case studies，that is，the 3-bus and 30-bus test systems. The algorithm performance was compared with that of mayfly optimization algorithm，elephant herding optimization（EHO），bat algorithm（BA），and directional bat algorithm（DBA）. The results evidence that the proposed approach has high convergence speed，high robustness，and acceptable computational burden，while providing the proper coordination of protection systems.

New energy has obvious volatility and anti-peak-shaving characteristics，and the integration of large-scale new energy into the power grid poses challenges to the peak-shaving. Hydrogen energy has a good potential for application as a potential peak-shaving resource. A multi-time scale peak-shaving scheduling model based on electrolytic hydrogen production was proposed with the aim of solving this problem. Firstly，the evaluation index model of peak-shaving capacity of electrolytic hydrogen was introduced and different types of electrolytic hydrogen peaking capacity were caculated. Meanwhile，an equivalent load disaggregation model based on coordinate distance minimization and wavelet transform techniques was constructed for matching different equivalent load components with different electrolytic hydrogen production systems. Subsequently，a multi-time scale peak-shaving scheduling scheme for different load components was proposed with the objective of improving the economics and effectiveness of peak-shaving. Finally，the validity of the proposed model was confirmed through simulations on the IEEE-30 node system.

Aiming at the problems of insufficient stability and low power generation efficiency of the existing power supply means for offshore ocean observation equipment，and low power density of direct drive wave energy power generation device due to the low running speed of ocean waves，it proposed to apply the magnetic lead screw（MLS） as a speed increasing device in the field of wave energy power generation，and based on its topology，the magnetic vector potential energy theory was introduced to establish a two-dimensional magnetic field analytical model，and the speed increasing operation mechanism of the magnetic lead screw was expounded. On this basis，the structure of surface-mounted magnetic lead screw was optimized and its thrust and torque performance was analyzed. Meanwhile，a magnetic lead screw composite generator was designed according to the optimization results，and the output power was compared with that of a cylindrical external permanent magnet linear generator under different wave speeds and load conditions. The simulation results show that the output power of the magnetic lead screw composite generator under the same volume was greatly improved compared with that of the cylindrical external permanent magnet linear generator in the low-speed wave motion condition，which is more suitable for the low-speed and large-thrust direct drive wave energy power generation field.

The synchronization accuracy of a multi-motor speed synchronization system is influenced by the motor control algorithm and synchronization control strategy. In response to the shortcomings of existing control strategies，a mid-range deviation coupling control strategy for multi-motor speed synchronization systems was proposed. Firstly，a mathematical model of multi permanent magnet synchronous motor was established. On the basis of the deviation coupling control strategy，the motor speed deviation was calculated using mid-range speed，and the structure of the deviation coupling control was optimized. The controller was designed using a nonsingular Terminal sliding mode control algorithm. Then，the Lyapunov stability theory was used to analyze the stability of the designed controller. Finally，a multi-motor synchronous control test platform was established for test verification，and the test data was analyzed. The results show that the proposed control strategy is effective and can improve the synchronization performance of the system.

Static var generator（SVG）can governance power quality，energy conservation and reduce consumption，furthermore it is an energy consumption product.The reasonable evaluation of the energy saving of the device has become an urgent problem to be solved. The power saving measurement technology of products was studied，and it was found that the existing power saving verification methods are not test methods. Because the field conditions are not unified，the verification results are not comparable. They can not be the data support of energy saving evaluation. At present，there is no set of effective testing methods in the field of inspection and testing that can be used for the power saving measurement of products in third-party testing laboratories，which makes both the testing work and energy saving evaluation work cannot be carried out.In order to make up for the above proposed detection technology gap，the innovative test method of design simulation resistance was proposed，so as to help complete the power saving measurement work. And a test platform was set up in the laboratory，to verify the feasibility and correctness of the method，and to assess the dispersion of the measurement results.The final conclusion is that the proposed method can be used for the third-party laboratory to complete the power saving measurement，flexible and controllable test conditions，can meet the requirements of various working conditions of the manufacturer，and the measurement results are comparable，can become the data support of energy saving evaluation，promote product iteration and update，and promote the progress of the industry.

The proportion of new energy sources connected to the station area is increasing day by day，which inevitably brings regulatory needs. Therefore，there is an urgent need for corresponding edge power flow algorithms. In order to give consideration to accuracy，practicality and efficiency under the situation of weak communication conditions and limited computing resources，a real-valued power flow algorithm for the edge computing of 400 V station area was proposed. Considering the resistive nature of the 400 V station area network and the high power factor of the equipment，the AC variables were simplified from vector sum to scalar sum；corresponding node transformation strategies and iterative algorithms were designed ；assignment strategies in the case of missing data was proposed；an online calculation strategy based on sensitivity correction or iterative calculation was further proposed. Through simulation analysis，the accuracy and practicality of the algorithm proposed were finally verified.

The participation of wind power and energy storage in primary frequency regulation of power grid can make better use of the advantages of wind power and energy storage for frequency regulation，which has gradually become a new trend. However，there are some problems in the coordination of wind power system and energy storage，such as insufficient utilization of energy storage and mismatch of wind power and energy storage power. Aiming at the above problems，an improved wind-storage combined primary frequency control strategy was proposed. Through frequency separation，design of six operating conditions and the switching rules，optimization of wind power and energy storage adaptive droop coefficient，the charging and discharging function of energy storage battery was realized，the power mismatch problem in operating condition switching was improved，and the excessive compensation of power shortage caused by this was avoided. Finally，the wind energy utilization efficiency and frequency regulation effect of the proposed control strategy and the existing control strategy were compared through simulation and wind storage experimental platform，and the effectiveness and superiority of the proposed control strategy were verified.

The traditional three-loop position control applied in the servo system with elasticity causes residual vibration around the objected position and has long trailing time. To address this issue，a mathematical model of the two-inertia system was established，and the causes of low-damping of the traditional position closed-loop structure were analyzed in detail. It was proposed to modify the speed loop structure combined with resonance-ratio control to guarantee the high-damping of the closed-loop system. The controller parameters were designed by use of the equal real part design，zero-pole elimination and polynomial method to achieve the high-damping characteristics. Simulation results show that the proposed high-damping position control can well suppress the fluctuation，achieve smooth position tracking，significantly reduce the trailing phenomenon compared with traditional P-PI method.

In order to improve the power coordination ability among microgrids in the microgrid group，it is necessary to consider the correlation between renewable energy generation output and the difference in load time distribution in different regions in the microgrid group planning. A scenario generation method that considers the spatio-temporal correlation of renewable energy power generation was proposed. Based on the spatial distance between microgrids in microgrids and the temporal characteristics of renewable energy power generation output，Nataf transformation and temporal reconstruction methods were used to generate scene-solar power output scenes that meet the temporal and spatial correlation. Then，the capacity allocation model of multi-objective microgrid group with minimum annual total cost and cumulative source-load difference was established. Finally，Jaya algorithm with non-dominated sorting and congestion improvement was adopted to solve the problem. Fuzzy membership function was used to evaluate the Pareto solution and select the optimal allocation scheme of wind storage in microgrid group. The results of the example show that the total investment cost can be effectively reduced by the precise allocation of the source storage capacity of the microgrid cluster，while the carbon emission level of the microgrid cluster can be reduced and the absorption capacity of renewable energy can be improved.