In order to solve the problem of overvoltage and overcurrent in the process of load sudden change for ion thruster screen grid power supply， the phase shift pulse frequency modulation （PS-PFM） was used to stabilize the output voltage of the LLC resonant converter. When the sampling voltage is lower than the lower limit of the set value， it enters into the frequency control mode， and when the sampling voltage is higher than the upper limit of the set value， it enters into the phase shift control mode. The experiment proves that， compared with the common frequency control， the addition of phase shift control can solve the problem of high voltage drift in light load or no-load mode， and through the adjustment of PID parameters， it can achieve stable and fast adjustment when the load jumps， so that the output voltage remains at the set value. Through the PCB layout and magnetic components optimization design， the developed principle prototype efficiency reaches 98.9% under rated conditions， and the power density reaches 6.47 \times {10}^6 \mathrm{ } \mathrm{W} / {\mathrm{m}}^3， which is advantageous in the same level of power supply products.

With the development of power electronics technology，microgrid type energy storage inverters with virtual synchronous generator（VSG） function have also been widely used. In VSG technology，due to the presence of inertial frequency regulation loop and voltage regulation loop，the inverter can realize the grid frequency regulation and voltage regulation function independently when it is connected to the grid，and it can realize the parallel power without communication when it is off-grid. However，in the microgrid system，due to the access of load and transformer，the parallel black start technology is one of the urgent problems to be solved when the inverter is off-grid. Through theoretical simulation analysis，an industrial frequency synchronous soft start method was proposed，which can realize smooth bus voltage establishment. The parallel power equalization of two VSGs during the soft start process achieved the completion of the black start of the whole system. Finally，the effectiveness of the parallel VSG black start control strategy was verified through experimental analysis.

Industrial communication technology is an effective way to achieve network control of industrial equipment. With the development of Ethernet technology in recent years，a top layer application technology based on Ethernet，PROFINET has rapidly developed. However，due to the lack of high-speed network interfaces in the lower layer devices，it is necessary to convert the control and status words in the high-speed communication protocol into a protocol that can be easily parsed by the lower layer devices，and then connect the devices to high-speed Ethernet. This scheme adopted the ERTEC200P-2 communication protocol chip for high-speed data exchange with external Ethernet，and the lower layer was connected to the frequency converter through the UART serial interface. The scheme has passed experimental verification and on-site verification，achieved good results

The state of charge （SOC） of batteries is one of the most important parameters in lithium-ion battery management technology，and high-precision SOC estimation is beneficial for the grid connection and control of energy storage stations. Battery charge and discharge data are not only time-series in nature，but also have certain spatial relationships between feature variables. To improve the accuracy and generality of the estimation method，a SOC estimation method was proposed for lithium-ion batteries based on a joint convolutional neural networks-long short term memory networks（CNN-LSTM） network structure. Firstly，the feature relationships between different dimensions of lithium-ion battery data were obtained through CNN feature extraction，and then the time series relationships were extracted through the LSTM network structure. The joint network fully captures the spatial and temporal characteristics of the battery dataset. The experimental results show that the average error of predicting battery SOC based on the CNN-LSTM joint network model is controlled at 0.65%，which is about 4.4% lower than the average error predicted by a single CNN network and about 0.2% lower than the average error predicted by a single LSTM network. It has good application prospects.

To address the issue that existing microgrid planning evaluation methods do not adequately account for the influence of uncertainties in the system and environment on the evaluation results，a microgrid planning evaluation method based on regret theory-vlsekriterijumska optimizacija i kompromisno resenje（VIKOR） was proposed. Firstly，a microgrid planning evaluation index system was constructed，which includes system economics，environmental protection and technology，taking into account the needs of the microgrid planning stage. Then，the analytic hierarchy process（AHP）-criteria importance though intercrieria correlation（CRITIC） method was used to assign weights to the indicators，taking into account the subjective experience of experts and the information contained in the objective data of the indicators. Finally，considering the influence of uncertainties on the evaluation results，the VIKOR method was improved by introducing the euphoria-regret function and state variables in the evaluation process based on regret theory，and a microgrid planning evaluation model based on regret theory-VIKOR method was established. The analysis of the example shows that the proposed evaluation method consider the influence of uncertainties in the system and environment as well as the psychological expectations of decision-makers on the evaluation results of the planning scheme，and is close to the actual microgrid planning scheme decision needs.

Under the "dual carbon" goal，the electric energy systems need to gradually develop towards the way of energy saving and low carbon. The integrated energy system （IES） is an important measure to solve energy and environmental protection problems. At present，the research on IES mainly focuses on distributed energy，energy storage grid connection and multi-objective optimization. Intelligent algorithm is an essential way to deal with optimization problems. However，with the complexity of the model，the traditional intelligent algorithms have the problem of poor convergence and easy to fall into the local optimum. Centering on the objectives of economy，environmental protection and stable operation，a multi-objective optimization model of IES based on improved particle swarm optimization considering three indicators of economy，environmental protection and output imbalance was built. Firstly，the IES model was established with the goal of optimizing the three indicators. Secondly，the membership function and the analytic hierarchy process （AHP） were used to normalize and determine the weight coefficient. Finally，the particle concentration evaluation operator was introduced to improve the particle swarm algorithm to solve the proposed model，and the operating results of the system under single-objective and multi-objective conditions were analyzed，which verifies the effectiveness of the model and algorithm. The improved algorithm significantly improve the convergence speed and effectively avoide the particles falling into the local optimum.

In order to study the distribution of magnetic field and temperature field of dry-type transformer iron core more accurately，analyze the influence of different excitation on the magnetic field loss and hot spot temperature rise of dry-type transformer core，firstly，Maxwell was used to calculate the transient magnetic field distribution of dry-type transformer，and the loss of the iron core under no-load condition was obtained. On this basis，a three-dimensional dry-type transformer magnetic field-temperature field coupling calculation method was proposed. The magnetic field loss was coupled to Fluent as the heat source of temperature field calculation，and the fluid structure coupling method was used to calculate the temperature field distribution of dry-type transformer. Finally，based on the above method，the magnetic field and temperature field of transformer core under harmonic action were calculated，and the influence of harmonic on core loss and temperature rise of dry-type transformer was analyzed，which provides a reference for the monitoring of the temperature rise about the transformer core under harmonics.

In order to effectively adjust and control the motion amplitude of the flexible manipulator and avoid large deviation between the actual motion track of the flexible manipulator and the target track，a flexible manipulator motion track control system based on the combination of distributed control system （DCS） and inertial weight was designed. It is a computer system that integrates computer，communication，display and control and is controlled by process control and process monitoring. The DCS algorithm was used to control the behavior amplitude of the monitored object and calculate the inertia weight of the flexible manipulator. The DCS-inertia weight combination was used to solve the specific value of the prime control index. The software design of the flexible manipulator motion trajectory control system was realized. The experimental results show that the motion amplitude of the end coordinates of the manipulator in the horizontal，vertical and spatial axes under the action of the DCS-inertia weight combination algorithm can be controlled within 10 units of length，and the optimal control state of the manipulator's motion trajectory can be entered within 0.52 s，with the maximum difference of the motion trajectory being only 0.01 rad，which verifies the feasibility and effectiveness of the system.

Voltage source converter（VSC） connected to weak AC power grid has the risk of small disturbance instability. Under the traditional control strategy，VSC has to reduce output power to maintain stable operation. In order to improve the stability of the weak grid connected VSC system，first established a universal analysis model for revealing the stability mechanism of weak grid connected VSC based on the AC voltage outer loop，and revealed the influence of the coupling characteristics among the phaselocked loop （PLL） and the VSC outer loop control on system stability. On this basis，a parameter adaptive control strategy for virtual parallel point was proposed. The detailed switch model of VSC in the PSCAD/EMTDC environment verifies the effectiveness of the proposed control method.

In order to solve the problem of low accuracy of small substation fault diagnosis，a small substation fault diagnosis model based on cooperative game and cloud model was proposed. By analyzing the characteristics and causes of faults，the diagnosis index system was established. Entropy method and expert weighting method were used to obtain index weight，cooperative game method was used to calculate consistency coefficient and combination weight，and the final fitting weight was obtained through normalization. Through the cloud model，the quantitative expression of each index was realized，and the weighted deviation degree was obtained. According to the weighted deviation degree，the final diagnosis result was determined. The experimental results show that the index weight distribution of the established model meets the consistency requirements，and the diagnostic accuracy of fault location and degree is high，which can provide more guarantee for the safe operation of substation.