The electricity power price setting mechanism will be fundamentally reformed with the continuous advancement of a new round of electricity market-oriented reform. Presently，some provincial and regional power grid enterprises are facing the problem of large fluctuations in electricity prices，which is not conducive to the in-depth promotion of electricity marketization reform. Firstly，based on the partial least squares method，the agency power purchase price formation model was established. Then，the main factors affecting the fluctuation of power purchase price were analyzed，and the mechanism of the influence of power supply and consumption balance on the price change of different types of electricity consumption was clarified. In order to reduce the fluctuation of electricity purchase price，a multi-objective optimization model of agent electricity purchase was established with the constraint of power supply and consumption balance. The actual example results show that the model can realize the reasonable distribution of power consumption among different types of power sources in the process of agent power purchase，and effectively reduce the fluctuation of agent power purchase price.

With the wide application of solar photovoltaic panels，the detection of hidden dangers and faults of photovoltaic panels has become more and more important. In order to improve the inspection efficiency of photovoltaic panels and the accuracy of defect detection，a target detection algorithm based on attention mechanism was designed and a complete inspection scheme of photovoltaic panels combined with UAV technology was proposed. The method uses the high-resolution camera mounted on the UAV for image acquisition，and detects and identifies the defects of photovoltaic panels through the combination of the object detection of the attention mechanism and the UAV technology. The experimental results show that the proposed method has high accuracy and reliability in photovoltaic panel inspection，mean average accuracy （mAP） reaches 83.2%，F1 score is 84.5%，effectively improve the quality and effect of photovoltaic panel inspection，and has high practical value.

Since the compressed air energy storage system grid-connected inverter voltage is always influenced by voltage fluctuations of the power grid with little problem，for the sake of ameliorating the dynamic and stable performance of the DC bus voltage of the inverter on the side of the grid and the actual output power of the system in the compressed air energy storage expansion power generation system and reducing the fluctuations，second-order linear active disturbance rejection control （LADRC） technique was used in the voltage outer loop control，a new-style double closed loop control construction was formed. The mathematical model of the grid-connected converter of expansion power generation system was established，the operating principle of LADRC was researched，and the conventional PI control was contrasted with the control methods studied. The simulation results indicate that when make a contrast with the conventional control methods，the control methods designed can make the DC voltage enter the stable state more quickly，the total harmonic distortion （THD） of the grid-connected current becomes smaller，and has better disturbance immunity.

Modular multilevel matrix converter （M3C） is a multilevel topology that can directly realize AC-AC conversion，which has good application prospects in high-voltage transmission systems and DC distribution systems，but the existence of bridge-arm circulating channels inside the M3C leads to a very complex control structure. For this reason，a hierarchical system control strategy was proposed. First，the mathematical model of the M3C was derived based on the conventional double αβ0 coordinate transformation. Then，a dual-loop control structure consisting of an outer-loop and an inner-loop controller was employed in the M3C，which is usually employed in voltage source converters. In addition，in order to suppress the loop current component inside the system，a bridge arm energy equalization control strategy based on double αβ0 transform decoupling was proposed，through which the capacitive voltage control between the bridge arm and the bridge arm was realized by this control and carrier phase shift modulation. Ultimately，the simulation model and physical prototype were constructed，and the outcomes validated the viability of the proposed control strategy for the M3C system.

In order to improve the compensation effect of LCL-type shunt active power filter，a frequency adaptive decimal delay repetitive control based on IIR filter was proposed. The resonance suppression loop of LCL was designed through root locus and the design result was used as a new control object for repetitive control. The IIR filter used could approximate the decimal delay caused by frequency changes，thereby matching the resonant frequency of repetitive control with the fundamental and harmonic frequencies of the power grid. The adaptive implementation diagram，the phase characteristics of the approximation part，and the design method of the compensator in sequence were presented. Finally，the stabilities of the system were analyzed. Simulation and experimental verification show that the proposed method can improve the steady-state tracking performance and THD of the system.

A fusion prediction method was proposed to predict and correct the calculation deviation of the top transformer oil temperature model in IEEE guideline，so as to realize the more precise prediction of the transformer top oil temperature（TOT）.Firstly，the characteristics of the transformer TOT model and the extreme learning machine（ELM） prediction model was introduced. Secondly，in order to avoid the problem of slow operation speed caused by double level intelligent prediction，the weighted multi-point extrapolation method combined with the load curve clustering algorithm was used to obtain the future load coefficient of the transformer which introduced as the load prediction level of the model. Finally，based on the calculation of thermal model，which the ELM was used to predict the deviation between the calculated value of thermal model and the measured value，and finally the accurate predicted value of the TOT of the transformer was obtained.The simulation platform was built and the simulation results show that the average prediction error rate of the proposed prediction method is only 0.59%，and the root mean square error is only 0.47 ℃. Compared with the other three methods，it has higher prediction accuracy and stability. The model training speed and prediction speed are only 1.21 ms and 0.39 ms，respectively，which proves that the fusion prediction model proposed and established has high prediction accuracy，stability and operation speed.

Aiming at the problem that the photovoltaic grid-connected inverter system operates under multiple disturbances，an linear active disturbance rejection control （LADRC） grid-connected strategy combined with photovoltaic system was proposed.Firstly，the dynamic process of PV grid-connected system was analyzed and modeled，and the LADRC-PM structure was designed according to the model characteristics of the photovoltaic system，further improving the speed on the basis of the classical structure. And then，the structure was introduced on the basis of the double closed-loop control framework，so that the system could compensate the disturbance through the feedforward way to enhance the system ability to suppress the uncertainty. Furthermore，the mathematical model of the proposed control strategy was dynamically analyzed using frequency domain analysis method，and its engineering stability，tracking convergence，and disturbance rejection superiority were theoretically verified，and the guidance of adjusting some parameters was given. Finally，the advantages of LADRC-PM control strategy was verified by the Matlab/Simulink simulation in various working conditions.

The stability analysis of power system transient voltage，power angle，and frequency is often based on short-time-scale electromechanical transient simulation，which requires a relatively accurate large-scale simulation model，which not only has low simulation efficiency but also takes a long time，thus giving rise to the demand for dynamic equivalence of large power grids. However，as the proportion of new energy increases，the power system gradually presents some unique characteristics of new power systems，with more significant differences in system inertia，frequency spatiotemporal distribution，and frequency modulation resource distribution. Conventional dynamic equivalence methods based on slow coherence theory are gradually difficult to ensure accuracy. To solve these problems，based on previous work，a large power grid dynamic equivalence method based on random forest algorithm was proposed. First，the large power system was divided into the study area and the external area. Then the external area on the opposite side of the study area tie line was equivalent to several nonlinear dynamic loads controlled by the random forest algorithm. The random forest algorithm was trained using the original model tie line's voltage/reactive power and frequency/active power relationships. A joint simulation model based on PSS/E and Matlab platform was established to achieve equivalent simplified electromechanical transient simulation，and Python environment was used to achieve information exchange and simulation control between them. Simplified results for the Northeastern United States power grid was presented and compared them with existing methods. The results show that the proposed method can effectively balance simulation accuracy and control stability.

With the accelerated construction of new power systems，the scale and complexity of transmission systems are constantly increasing. Therefore，it is urgent to study transmission line fault diagnosis algorithms that utilize multi-source data as driving sources and meet requirements for accuracy and low time consumption. A multi-source information fusion transmission line fault diagnosis method based on the improved NRBO-XGBoost algorithm was proposed. Firstly，by analyzing the measured electrical quantities and action switch quantities on both sides of the line protection，the correlation features of time/frequency domain differential current and differential voltage，transient polarity，and action signals under internal and external fault scenarios were decoupled. Then，the decoupled multi-source fault feature vectors were input into the XGBoost serial learning algorithm，and the NRBO algorithm was introduced to globally optimize the training parameters of XGBoost. Finally，based on the identification output of the improved NRBO-XGBoost algorithm，a complete transmission line fault diagnosis model for internal and external faults was obtained. An IEEE-30 standard node transmission system model was constructed using PSCAD/EMTDC. Through testing in four typical scenarios，the results demonstrated that the proposed multi-source information fusion algorithm achieves a line fault diagnosis accuracy of 99%，meeting the required threshold. Additionally，it exhibits certain advantages in terms of diagnosis speed compared to traditional intelligent algorithms.

The development of modern power systems with wide span，low inertia，and complex structure makes the frequency stability problem increasingly prominent，and the spatial-temporal distribution characteristics of frequency are distinct. Taking the actual power grid as the object，the impacts of large-scale new energy access and DC power control on the grid frequency response under disturbances and the characteristics of frequency spatial-temporal distribution were analyzed. Firstly，based on the detailed time-domain simulation model，the causes of the spatial-temporal distribution of node frequency were discussed from the perspective of the distribution differences of disturbed power，inertia，and frequency regulation resources. The system-level and node-level frequency response indicators that reflect the overall trend and distribution differences of grid frequency response were proposed. Then，the impact mechanisms of factors such as the new energy power proportion，the distribution of synchronous，the primary frequency regulation of new energy，and DC frequency limit control on the grid frequency response under disturbances were analyzed. Finally，through simulation results of real power grid cases，the impact of various factors on the grid frequency response and its spatial-temporal distribution characteristics was quantitatively analyzed.