To address the supply-demand imbalance caused by renewable energy intermittency and load fluctuations in islanded microgrids，a two-layer optimization-based dynamic time-of-use（TOU）pricing scheduling model was proposed，aiming to enhance economic efficiency and operational stability.First，a comprehensive microgrid system model was established，integrating wind，photovoltaic，energy storage，marine energy，and diesel generators，while introducing a dynamic TOU pricing mechanism to guide user load behavior for peak shaving and valley filling.Subsequently，a two-layer optimization framework was constructed：the upper layer adjusts load distribution via dynamic pricing，and the lower layer optimizes generation dispatch and energy storage strategies to minimize operational costs，effectively resolving the limitations of traditional single-layer optimization in handling complex nonlinear constraints. Case studies demonstrate that the proposed model significantly reduces reliance on diesel generators，enhances adaptability to renewable energy fluctuations，and optimizes operational costs.The findings provide theoretical support for low-carbon scheduling of islanded microgrids，balancing economic and reliability objectives，and offer practical insights for advancing energy transition in island regions.

Accurate short-term electrical load forecasting is of great significance for the design and optimization scheduling of integrated energy systems（IES）. However，the load data in real integrated energy systems are low-quality and fluctuating，so the forecasting accuracy of existing prediction models is low. A short-term electrical load forecasting method based on attention-based long short-term memory（AT-LSTM）and Stacking learning was proposed. Under the framework of Stacking ensemble learning，AT-LSTM，random forest and decision tree were ensembled to forecast short-term electrical load which can make up for the low prediction accuracy of a single model. Based on the exploratory analysis results of data，the data feature engineering model was constructed to input features，and this prediction method was used for short-term electricity load prediction. The experimental results of the integrated energy system in Beijing show that compared to other algorithms，the proposed method has a maximum prediction error reduction of 24.8%.

Space vector pulse width modulation（SVPWM）strategy is one of the key technologies for three-level inverters.However，conventional three-level SVPWM often experiences neutral point potential（NPP）oscillation and high switching loss when addressing the neutral point potential balancing issue.To tackle this challenge，firstly，the fundamental principles of the traditional nearest three vector（NTV）synthesis strategy and the virtual space vector pulse width modulation（VSVPWM）strategy were reviewed. And then，the drawbacks of the NTV approach based on the conventional region partitioning method was analyzed. A dynamic partitioning method was proposed to resolve the neutral point potential offset caused by conventional partitioning.Furthermore，to counteract the NPP oscillation of the NTV under high modulation，a strategy that employs a synthesis of four-effective voltage vectors was introduced. Compared to VSVPWM，the proposed strategy significantly reduced the inverter's switching loss.Ultimately，the effectiveness and superiority of the proposed algorithm were validated through experimental results.

In response to the existing problems of traditional diode based clamp type wind turbine inverters，a hybrid clamp type structure was introduced. Based on the analysis of its working principle，a method for switching the switch state and a vector optimization selection method that can avoid modulation waveform burr line voltage were proposed，achieving balanced control of clamp capacitor and DC bus capacitor voltage. A third-order low-pass filter method with initial angle calculation was proposed to optimize the virtual flux orientation control strategy for the control of hybrid clamp type rectifiers in the unit. A direct power tracking control method for rectifiers based on improved virtual flux orientation was also presented. Finally，simulation and experiments were conducted on the system，confirming the correctness and effectiveness of the proposed method.

With the emergence of a large number of distributed power generations，various unbalanced and nonlinear loads are connected to the power grid，resulting in the distortion of the grid current，which brings adverse effects to both the power grid and electrical equipment. A multifunctional energy storage converter was proposed，which is capable of simultaneously realizing the compensation of reactive current，harmonic current and unbalanced current of the load. This converter used a phase-locked loop based on double second-order generalized integrators to generate the required phase angle and frequency，and at the same time obtained the amplitude of the positive sequence component of the voltage.The converter obtained the command current by obtaining the positive sequence component of the load current and performing coordinate transformation，and then controled through the difference between the command current and the output current of the inverter to track the command signal.Proportional resonant control was used to obtain three-phase current，and pulses were generated through three-dimensional space vector control to control the conduction of the switch tube. By comparing with traditional energy storage converters，digital and analog hybrid experimental results have proven the effectiveness and reliability of this scheme.

Aiming at the problem of large switching loss of modular multilevel converter（MMC），starting from the switching frequency optimization strategy，the existing switching frequency optimization strategy was improved，and the accurate analytical formula of sub-module capacitor voltage based on the real-time value of MMC transmission power was derived，so as to calculate the fluctuation range of the mean value of capacitor voltage.The dynamic retention factor was obtained by using the margin between the mean value of capacitor voltage and the engineering constraint，and the final output switching instruction was realized by the main flow of the equalization strategy.The PSCAD/EMTDC model was built based on the offshore wind power flexible engineering parameters to verify and compare the proposed strategy with the traditional strategy.The simulation results show that under the premise of meeting the requirements of the project on the fluctuation range and the imbalance index，the switching frequency of the proposed strategy is reduced by 49%~58% compared with the traditional strategy under each steady-state condition，and the switching loss is reduced by 63%~90% under each steady-state condition，and the expected loss reduction effect is achieved.

The traditional predictive current control for three-phase LCL grid connected inverters has the problems of large steady-state ripple and unstable switching frequency，which is not conducive to the quality of grid connected current and the design of filters. Therefore，an improved three vector fixed frequency predictive current control method was proposed.By applying three vectors within one control cycle，the control degrees of freedom were maximized. Firstly，an active damping method based on capacitor voltage feedback was designed to suppress resonance. Then，a duty cycle calculation method based on inverter side current deadbeat control and a seven segment symmetric pulse generation scheme were proposed. The simulation results and test results verified the superiority of the proposed method in improving dynamic performance，steady-state performance and fixing switching frequency.

The load of a submerged arc furnace has many advantages，such as large single-unit regulation capacity，good communication conditions，easy control，and low economic retrofitting，making it an important flexible regulation resource for the power grid.However，there is currently a lack of effective digital simulation methods for modeling submerged arc furnace systems and their regulation characteristics.A time-domain digital simulation model for the power supply system of an industrial submerged arc furnace was established，which included an electric furnace transformer，short network，furnace body，and reactive power compensation，based on the actual electrical operating conditions of the submerged arc furnace.The power regulation characteristics of the submerged arc furnace were determined by representing the electrode regulation link with the time-varying arc length calculated through the Newton downhill method.The equivalent time-varying resistance was obtained by solving the arc differential equation using the Runge-Kutta method，enabling simulation of the power regulation process of the submerged arc furnace.This was achieved by encapsulating it with a custom module and integrating it with the system model to realize time-domain digital simulation.It is applicable to both AC submerged arc furnace and various electrode control strategies，and can be widely used for simulating the load characteristics of submerged arc furnace，flexibility resource assessment，and as a simulation platform for participating in grid interaction research.

The back-to-back active neutral-point-clamped（ANPC）converter，as the core component of the unified power flow controller of the distribution network，is widely used for the flexible closed-loop operation.However，the ANPC converter has more switching devices and commutation paths，which significantly increases the complexity of modeling.To solve the above problems，an average modeling method of the ANPC converter was proposed.The controlled source equivalent substitution method was used to replace the switching devices.The resistance-capacitance-inductance devices of other parts of the circuit were retained while averaging each branch，which greatly simplified the circuit model of the ANPC converter. On this basis，combined with the flexible control principle based on back-to-back ANPC converters，the average model of a back-to-back ANPC flexible control system was further built. By comparing the simulation results of the switch model and the average model，it was shown that the average model was consistent with the switch model in the internal branch and external characteristics，which verified the correctness and accuracy of the proposed average model and its feasibility in the application of flexible closed-loop system.

In order to eliminate the problem of low inertia and large frequency fluctuation in wind power grid-connected system when power disturbance occurs，an improved virtual inertia control strategy was proposed.A cooperative control strategy of adaptive moment of inertia and damping coefficient was introduced in the main control system of wind power inverter. The energy storage static synchronous compensator（STATCOM/BESS）was used to provide the active power and reactive power required by the system. At the same time，the power output of STATCOM/BESS was adjusted according to the frequency deviation and change rate of the system. By analyzing the small signal model of virtual synchronous generator（VSG）of the fan，the setting rules of the adaptive VSG moment of inertia and damping coefficient were determined. The Matlab/Simulink simulation results show that the strategy has a more obvious effect on frequency fluctuation，and can effectively suppress the voltage drop of the fan junction point，and improve the ability of safe and stable operation of the system.