Three-phase asynchronous motor is one of the most frequently used motors. Inter-turn short circuit fault is a kind of fault with high probability. If the real-time monitoring of motor operation，health and safety evaluation of the operation，will be able to timely stop losses，reduce losses. An inter-turn fault diagnosis method was proposed based on extended Clarke transform and fault characteristic factor Q，analyzed the characteristics of Clarke vector of inter-turn fault of motor，modulated the Clarke vector of inter-turn fault of motor，and obtained the DC component of symmetrical component and the AC component twice the fundamental frequency in the three-phase current. The ratio of the amplitude of the component to the DC component was used as the fault characteristic factor Q to diagnose the inter-turn fault. Clarke vector spectrum was studied by characteristic factor Q，so as to judge the motor fault，and theoretical simulation and prototype test were carried out.

Due to the advantages of faster dynamic performance and smaller torque ripple， high frequency pulse voltage injection （PSVI） is widely used in sensorless control of permanent magnet synchronous motor （PMSM） at low-speed range. Under low switching frequency， the dynamic and steady performance of the traditional high frequency pulse voltage injection method is seriously affected due to the larger system delay， the high-frequency phase update delay caused by the special control structure， and the increase of the phase delay caused by the lower cut-off frequency of the filter. In view of the above problems， compensation schemes for different non-ideal factors were proposed based on the detailed analysis of the influence of the filter phase delay and the delayed phase update of high frequency pulse voltage under low switching frequency on the rotor position estimation. Finally， the influence of the above non-ideal factors and the compensation scheme were simulated and verified. The simulation results show that the proposed solution can effectively reduce the rotor position estimation error.

In the context of dual carbon，carbon trading mechanism and various energy complementary power generation mechanism are important mechanisms for China to achieve carbon emission reduction goals and sustainable development. A multi-energy system optimization model was proposed that takes into account carbon trading to reduce carbon dioxide emissions while relieving the pressure of thermal power unit peaking. Firstly，a cost model of carbon trading was constructed based on carbon emissions，taking into account coal consumption cost，fuel input and loss cost and environmental cost，to form an optimal objective function and linearize it by segments. Secondly，the model for hydro-thermal-wind-photovoltaic power system was constructed. In the first stage，with the objective of minimizing net load fluctuation，the generation capacity of each hydropower station of the terrace was calculated using the moth search （MS） algorithm，and the daily load output curve was optimized. In the second stage，with the objective of minimizing the integrated cost and describing the stochasticity of wind power with the help of scenario method，a dispatching model of power system considering carbon trading mechanism was constructed. Finally，the validity of the proposed model was verified in a modified IEEE 7-machine 57-bus system.

Flux-weakening control technology can effectively broaden the speed range of the permanent magnet synchronous machine（PMSM）， therefore， it is of great significance to the research on the flux-weakening control of permanent magnet synchronous machine. Most of flux-weakening modified the flux-weakening current command through a single PI link， and its response speed is slow and difficult to meet the high-performance control requirements， and due to the high coupling and nonlinearity of the flux-weakening loop， PI parameters setting is difficult. In order to solve the above shortage， a method of using a conversion look-up table was proposed to be added to the control system as a feedforward， having accelerated the speed of flux-weakening adjustment.While， the method of gain linearization was adopted， by analyzing the changes of the small signal model at different operating points， it solved the problem that the fixed PI parameters of the flux-weakening loop controller that have been set by experience cannot cope with the change of the operating point， which improved the stability and accuracy of the system. Finally， according to the simulation and experiments， it was verified that the improved method can improve the performance of flux-weakening control.

As the penetration rate of new energy and power electronic equipment increases，the inertia and damping of the power system decrease，and the stability decreases.The grid-forming control technology builds a voltage source to support the stable operation of the large power grid through the converter，so as to play the role of rapid frequency and voltage regulation，increase inertia and short-circuit capacity support，and suppress broadband oscillation，so it has gradually attracted attention. Firstly，the differences between the grid-following converter and the grid-forming converter were compared，and the grid-forming control technology was more suitable for the new power system. Secondly，according to the four different control strategies of the grid-forming converter，the control mechanism of these strategies was analyzed in principle.Finally，by using the same initial parameters and simulating the influence of different control strategies on the power grid frequency after the power grid was disturbed by common disturbances，the superiority of VSG control strategy was verified，and the influence of VSG virtual moment of inertia and damping coefficient on the output frequency response of the system was discussed，which provides a reference for further in-depth research.

During the joint operation of permanent magnet direct drive wind power generation systems，the changes in motor side parameters may cause problems such as reduce control accuracy and stability on the machine side，which in turn affects the DC bus voltage of the converter，leading to power fluctuations on the grid side and posing a threat to the stability of the power system. When using traditional single vector model free predictive control on the machine side，although it effectively improves system robustness，there is still a problem of poor control effect. Therefore，an improved model free predictive control suitable for permanent magnet direct drive wind power generation systems was proposed to maintain system robustness while improving steady-state control performance. Firstly，the machine side and grid side models during the joint operation of the system were analyzed. Secondly，through the method of the extended finite control set，the traditional finite control set was optimized. Combined with the model free predictive control concept of traditional current difference，the proposed method improves the prediction accuracy of the control method and reduces current and power ripple. Finally，the effectiveness and superiority of the proposed method were verified through experiments.

With the continuous development of renewable energy sources and the increasing share of renewable energy in the grid，optimal coordination of maintenance work becomes increasingly important in order to ensure the safety of power supply in power systems considering renewable energy access. Current tools for maintenance planning are constrained by operational safety standards and the complexity of the grid，and have problems such as low operability and high computational effort to simulate accidents. To reduce the burden of manual computation，the use of machine learning models was proposed to predict the outcome of emergency situations in a fast and reliable manner. The method was tested in a regional facility in Lanzhou，covering voltage levels of 10 kV and 220 kV. By testing and comparing a plain Bayesian classifier，a support vector machine （SVM）and a decision tree-based model，it was shown that the decision tree-based random forest algorithm is consistently better than other algorithms in identifying safe serviceable time periods with an accuracy rate higher than 90%. In addition，it was shown experimentally that the expected growth in renewable energy generation will affect the future serviceability of the power system，with a 20% increase in non-safe serviceable time periods in some areas.

The integration of large-scale wind power，photovoltaic and other renewable energy resources for the power system will greatly change the power supply characteristics，reducing the inertia of power system and threatening the stability of transient frequency. The virtual synchronous generator（VSG） technology can improve the inertia of renewable energy to promote the stability of transient frequency. In order to quantitatively describe the characteristics of transient frequency of VSG and enhance the control ability of VSG，the transient frequency model of VSG needs to be studied urgently. Based on the VSG control strategy of renewable energy，considering the inertial response，primary frequency regulation of renewable energy，the transient frequency model of VSG was established，and a Matlab/Simulink based simulation model was built to verify the validity of the established analytical model. Finally，the influence of different control parameters on the transient frequency of VSG was analyzed，and the effect of control parameters on the transient frequency of VSG was clarified，giving the guidance for system frequency stabilization.

To address the issue of transient overvoltage at the sending end of the wind farm caused by faults in conventional high-voltage direct current systems system，the impact mechanism of DC faults on transient voltage changes at the sending end was analyzed. It was discovered that the reactive power surplus of the AC system after the fault was the root cause of the sudden voltage rise. To address this，a reactive power coordination control strategy based on distributed synchronous condensers and doubly fed induction generators（DFIG） was proposed. A distributed synchronous condenser was installed at the grid-connected bus of the wind farm to stabilize the grid-connected voltage and improve the low-voltage or high-voltage ride-through capability of the wind farm using its unique reactive power regulation characteristics. During various severe fault scenarios in the DC system，the DFIG participated in reactive power regulation by changing the reactive power reference value，and improved system voltage during the fault period with the distributed synchronous condenser. The DFIG wind farm was controlled to exit reactive power regulation during steady-state after the fault，to ensure economic operation after fault recovery. Simulation results using PSCAD software demonstrate that the proposed reactive power coordination control strategy effectively suppress transient voltage variations of the wind farm after faults，improving the reliability and economy of the wind farm，particularly during commutation failure and direct current blocking in the system.

To enhance the economic and operational flexibility of accompanying energy storage facilities in new energy power stations，as well as to improve the stability of supplying electricity directly to large users and the grid-friendliness of large-scale new energy power stations，a two-stage robust configuration and optimized operation strategy for hybrid energy storage on the generation side was proposed. In the first stage，based on the empirical mode decomposition and Hilbert-Huang transform of demand power signals，considering the investment cost of energy storage and the supply-demand requirements of new energy power stations and grid integration，a robust configuration model for various types of energy storage units in the hybrid system was constructed. In the second stage，with the first-stage optimized configuration as a constraint，an optimization model for the operation of hybrid energy storage was developed with the objective of reducing net load fluctuations while meeting the power supply requirements of the power station and grid integration.The effectiveness and competitiveness of the proposed models and strategies were demonstrated through case studies using actual wind power and load data from a certain province，providing technical support and decision-making references for the coordinated development of new energy power stations and energy storage.