A sliding mode linear self disturbance rejection control strategy was proposed to address the output voltage fluctuations caused by sudden load changes，changes in DC bus voltage，disturbance addition，and other disturbances in three-phase interleaved parallel DC-DC converters. Firstly，a mathematical model of three-phase interleaved parallel DC-DC converter in the s domain was established and the principle of energy transmission imbalance was analyzed. Then，based on the system order，appropriate observers and linear auto-disturbance rejection controllers were designed. Furthermore，in order to improve the ability to suppress the fluctuation of the output voltage of the system，sliding mode control was introduced to form a sliding mode linear auto disturbance rejection control，which improves the anti-interference and rapidity of the system.Finally，multiple operating conditions were designed to simulate and verify the new control strategy. The results show that compared with traditional control strategies，sliding mode linear active disturbance rejection control not only has excellent voltage fluctuation suppression ability，but also has superior steady-state operation ability and transient traversal ability，ensuring the balance between system capability transmission.

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.

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.

With the proposal of the "dual carbon" goal，the application of EVs is becoming increasingly widespread. In order to further reduce the charging cost of EVs so as to easing the charging cost burden of EV users，a coordinated control strategy for EV charging DC microgrid was proposed，which includes photovoltaic（PV），energy storage system（ESS）and power grid. This strategy can coordinate the input and output states of different ports based on the power relationship between each port，reduce the fluctuation of EV charging load through peak shaving and valley filling thus lowering the charging cost. Firstly，the control strategies of PV and ESS were introduced. Then，Monte Carlo algorithm was used to predict the charging load of EVs. Next，six modes and four voltage bands during microgrid operating was divided，mode switching condition and coordinated control strategies between each port were proposed. Subsequently，the feasibility of coordinated control was verified in Matlab/Simulink and Yuankuan semi-physical simulation platform. Finally，by calculating EV charging costs under five typical weather scenarios and comparing them with other literature，it was found that the proposed strategy can reduce charging costs by up to 28.1%，its significant effect in reducing costs was demonstrated.

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.

Transmission line tower as the normal operation of the power system of the necessary equipment，its grounding resistance accurate detection for the safe and stable operation of the entire power system is particularly important，especially in the judgment of lightning protection performance and other aspects. Thus，a multi-frequency tower grounding resistance measurement method was proposed based on radial basis function （RBF） fitting. The method was able to use multi-frequency current as an excitation under the premise of not disconnecting the tower grounding lead，measure the grounding resistance value obtained from the input current of different frequencies，and then use radial basis function neural network fitting based on these data to realize the accurate measurement of the tower grounding resistance. At the same time，the accuracy and reliability of the method was proved through the measurement of grounding resistance of multiple towers，and the proposed method is simple to operate，which largely facilitates the measurement of inspectors on the spot，and has strong practical significance.

Because of crystal oscillator error，inter-symbol interference and baseline drift in industrial optical fiber communication，the optical fiber receiver has the problem of high error rate of data recovery. In long-distance industrial communication，the electrical level jitter of serial data at the receiver will increase. To solve this problem，a method of clock and data recovery for long-distance industrial optical fiber communication was proposed. Six-times frequency clock was used for sampling. The rising or falling edge of serial data can be determined and collected under the same clock，which can select dynamical sampling clock. According to the electrical level jitter tolerance，the validity of the sampled data under different conditions can be verified. After data processing，the six-times sampled data was restored to serial data under the local clock，which is finally converted to the parallel data. Simulation and test verified the effectiveness of the proposed method.

The power cable plays a very important role in today's social development and urban operation. With the increase of people's electricity consumption，the amount of cable laying is also increasing synchronously.In order to prevent the cable from being damaged，the environmental vibration signals around the cable duct gallery are monitored，and potential threats are found in time to ensure the normal operation of the cable，a vibration monitoring system for underground cable damage prevention based on Matlab wavelet noise reduction algorithm and EMD-AR spectrum analysis was proposed. The system was composed of solar power supply module，six axis gyroscope attitude sensing module，vibration sensor module and internet of things communication module.The main control chip uses STM32F4 microcontroller. The wavelet threshold de-noising algorithm was used to remove the complex high-frequency noise and improve the signal identifiability. Then the de-noised signal was subjected to empirical mode decomposition（EMD）and AR spectrum analysis of the first six intrinsic mode function（IMF）components.Finally，the AR spectrum of the first six IMF components was accumulated to obtain the energy contrast map of the signal. The research shows that the application of this method can accurately analyze the type of vibration，which can provide a more simple and convenient method for the monitoring and analysis of vibration near the cable duct gallery，and effectively protect the safe and stable operation of the cable.

Under the dual carbon background of AC and DC hybrid power grids have the new feature of "strong HVDC and weak AC system" and power electronization， in order to effectively reduce the risk of large-scale power outages in power grid，it is necessary to build a secure and reliable comprehensive defense system to ensure the stable operation of the power system. Based on the traditional three defense lines in China，the objectives and design principles of the UHV AC and DC power grid security defense system that adapt to the dual carbon background of China's power grid were determined，and designed the overall structure of the UHV AC/DC power grid security defense system，main functions and specific configuration schemes.

The traditional ultra high speed permanent magnet synchronous motor（PMSM）driver uses PWM equivalent sine voltage output，which leads to severe motor heating due to large harmonics，and it cannot be used in situations where the input voltage changes over a large range，such as fuel cells. To reduce the heat generated by the motor and further expand its application scenarios，a new sine wave voltage output inverter based on three-phase DC/DC converter was proposed，a 120 kr/min ultra high speed PMSM was successfully driven. The experimental results show that the output voltage harmonics of the three-phase sine wave voltage output inverter are lower than those of traditional inverters，which reduces the heat generation of the motor under high speed conditions and has practical engineering application value.