Aiming at the characteristics of interconnection and multi-source in modern power systems, a heuristic intelligent optimization algorithm is proposed to assist multi-area interconnected power systems with wind, solar, water, thermal storage to optimize load frequency control. This method takes the area control error of each region as the objective function, and uses the advantages of whale intelligent optimization algorithm, such as strong robustness, high solution accuracy and fast convergence speed to jointly optimize the parameters of the PID load frequency controller in each region, so that the system can maintain frequency stability and long-term safe operation under various random disturbances. Finally, a three-area interconnected power system model with wind, solar, water and thermal storage is established to compare the frequency and tie line power deviation of the interconnected power system in different optimization tuning methods, and test the stability of the system in different regions under different disturbances and the effectiveness of the proposed method. The experimental results show that the coordinated optimization tuning method of the multi-area interconnected load frequency controller adopted in this paper effectively improves the stability of the system, and has good robustness and practicality.

In order to study the influence mechanism of rotor-side converter and its control system on damping characteristics of doubly-fed wind turbine, a dynamic model of the wind turbine under small disturbance state is constructed considering mechanical torque, electromagnetic torque, transient potential, rotor-side converter control, voltage control and angle offset. Then, the damping torque and synchronous torque expressions of the doubly-fed wind turbine are derived based on the complex torque coefficient method. The damping torque is related to the oscillation frequency, wind speed, mechanical parameters, electrical parameters and control system parameters of the wind turbine, and the control parameters of the inner and outer loops of the rotor-side converter are coupled with each other to affect the damping of the wind turbine. Finally, the mathematical model is verified by time domain simulation and frequency domain simulation. The results show that the model has applicability at different oscillation frequencies.

Dual-rotor wind turbine with high-soft tower can break the limits of wind energy utilization of conventional single-wheel wind turbines and improve the efficiency of wind energy utilization in low wind speed areas. The natural frequency of the flexible tower is within the operating speed range of the wind turbine, so there is a speed exclusion zone. Based on the normal operation control of wind turbine, a resonance crossing control algorithm is proposed to prevent the resonance between the wind turbine impeller and the tower during operation. The algorithm finds the resonance interval through Campbell diagram, and adds speed control on the basis of optimal torque control to achieve fast resonance crossing. A large number of simulation tests were carried out on a simple wind turbine model developed on Simulink for steady-state wind and in three scenarios with different turbulence intensities. The simulation results show that the algorithm can achieve fast and effective resonance traversal under all the above conditions.

In order to reduce the adverse impact of wind power fluctuation and anti-peak shaving on power grid operation, a coordinated optimal dispatching strategy of "wind-grid-EV charging and swapping station" considering wind power consumption is proposed. Firstly, thermal power is used as an adjustable power supply to assist wind power grid, and through the carbon trading mechanism, the thermal power system is encouraged to actively reduce output and reduce carbon during periods of low grid load and high wind abandonment rate, so as to effectively improve the wind power grid space. Then, on the basis of meeting the power demand of the power grid, the load of the charging and changing power station is connected to further restrain the fluctuation of wind power, and at the same time, the wind power consumption is increased. The objective function is to minimize the peak valley difference of power grid load and optimize the comprehensive operation cost of the system. The low-carbon economic operation model of the joint system is constructed. Finally, the NSGA-Ⅱ algorithm is used to solve and analyze different scenarios. The results show that, this strategy can effectively reduce the system operation cost and the peak valley difference of grid load, and improve the wind power consumption rate of the grid.

With the rapid development of wind power industry, the number of wasted wind turbine blades increased significantly year by year, which brings great environment pressure. Against this problem, the influence of atmosphere on the generation characteristics of gas, liquid and solid products of wasted wind turbine blades during thermal treatment at different temperatures was studied, to provide reference for thermal recovery strategies. The results showed that, in N₂ and CO₂ atmospheres, the production of combustible CH₄ reached the highest at 800 ℃, that of CO increased with temperature. Tar products in each atmosphere mainly consisted of p-isopropenyl phenol, p-isopropyl phenol and bisphenol A. Moreover, it was found in the experiment that, at high temperature, CO₂ in the atmosphere effectively prevented the formation of polycyclic aromatic hydrocarbons (PAHs) in tar, which is helpful to subsequent treatment of tar. It is also found that, the coke yield in air and CO₂ atmosphere was higher than that in N₂ atmosphere, however, at higher temperatures (600 ℃ and above), the results were opposite. This may be due to different carbonization levels in different atmospheres at low temperatures.

This paper studies how to mitigate the blade root flap-wise moment of wind turbine under the influence of wind shear and tower shadow effect. An individual pitch control strategy based on simplex method is proposed to mitigate the blade root flap-wise moment and its 1p component load on the basis of ensuring the power control of the wind turbine. This method and the individual pitch control strategy of conventional PI control are applied to a 4.5 MW wind turbine model, and simulation is carried out under turbulent wind conditions to compare and analyze the blade root flap-wise moment, its power spectral density and the output power. The analysis of the simulation operation data of the 4.5 MW wind turbine model shows that, the individual pitch control strategy based on the simplex method can effectively mitigate the blade root flap-wise moment and its 1p component, and stabilize the output power.

Phase change energy storage technology has the advantages of high heat storage density and constant temperature, so it has great potential for large-scale commercialization. The development of phase change materials is very important to the application of phase change energy storage technology. To solve the problems of poor heat transfer performance and easy leakage of phase change materials, extensive research has been conducted based on the heat transfer enhancement and packaging of phase change materials. The characteristics of thermal energy storage technologies are firstly compared. Then, the classification and properties of phase change materials are summarized. The progress of heat transfer and storge enhancement is discussed from the aspects of increasing heat transfer area, thermal conductivity, melting latent heat and specific heat capacity. The packaging of phase change materials is also discussed. Finally, a prospect for the future development direction of phase change energy storage is made.

In order to reduce the phenomenon of "wind and solar energy power abandonment" caused by the mismatch between the on-grid electricity generated by renewable energy power and coal-fired power unit, the coal-fired power unit needs to achieve the deep peak shaving to provide the grid space for renewable energy power with the continuous increase of the installed capacity of renewable energy. At the same time, the coal-fired power unit provides the ability to further consume renewable energy power. The utilization of coupling reheated steam extraction with thermal energy storage and molten salt thermal energy storage heated by renewable energy power in deep peak shaving system of coal- fired power unit is proposed. The research on large-scale renewable energy power consumption by peak shaving system of coal-fired power unit integrated with thermal energy storage is discussed. Moreover, the comprehensive coal consumption for power generation and the CO₂ emission is analyzed. The results show that, the power output of the coal-fired unit decreases from 300.03 MW to 210.07 MW when the reheated steam extraction mass flowrate is 270.70 t/h, and the maximum power of renewable energy power consumption by thermal energy storage system is 187.26 MW. When the stored heat is released, the power output of coal-fired unit increases from 300.03 MW to 348.68 MW. When the renewable energy power consumption per unit time is 187.26 MWh, the comprehensive coal consumption for power generation is reduced by 8.49 g/kWh and the CO₂ emission is reduced by 28.23 t. This study provides a guiding idea for the absorption of high-proportion renewable energy power.

Electric-heat conversion is an effective way to realize local consumption of new energy and help build a clean and low-carbon heating system. To this end, a new heating substation system with new energy consumption capability is designed. The system is based on the traditional heating substation, and the adjustment equipment such as the electric boiler and heat storage tank is added. At the same time, a heating substation dispatch strategy based on the coordinated regulation of flexible resources such as the primary heat source and heat storage tank is proposed to achieve complete consumption of new energy, meet the heat load demand, and obtain the required energy capacity of the heat storage tank. Furthermore, the configuration method of the volume of the heat storage tank and its structural parameters considering the dynamic characteristics of charging is proposed to calculate the volume of hot water injected into the heat storage tank and the volume considering the thickness of the thermocline layer. The inlet and outlet pipe diameters of the heat storage tank determine through the maximum heat charging flow. Appropriate ratio of diameter to height is selected to ensure the ideal temperature stratification characteristics of the heat storage tank. The effectiveness of the proposed method is verified by a simulation example. This method can provide a reference for the local consumption of new energy and the construction of heating substations.

There is an increasing participation of thermal power units in peak shaving of power grid due to the national "double carbon" target and the strategic demand of energy transformation in China. The molten salt heat storage system can substantially improve the peak shaving capacity of thermal power system by absorbing or releasing heat efficiently from or into the thermal system. The key technologies of thermal power units coupled with molten salt heat storage system and the research progress of the heat storage system process flow design are combed in detail. Firstly, the formulas and physicochemical properties of commonly used molten salts are summarized. Great attention is paid to the characteristics and application prospects of the currently widely used binary and ternary nitric acid molten salts. Secondly, the critical equipment components including the thermal storage tank as well as heat exchangers used in the heat storage system are elaborated. The heat storage principle and characteristics of single-tank and double-tank molten salt heat storage methods are summarized, and the applicability of the former two methods to thermal power units' heat storage and peak shaving system is analyzed from the perspectives of system safety, cost, technology maturity and peak shaving response speed. Then, the current research status of molten salt heat exchanger is summarized, and the research achievements and shortcomings of molten salt-steam-water tube shell heat exchanger are emphatically analyzed from multiple perspectives. Moreover, the design schemes of molten salt heat storage system are sorted out emphatically for the process of heat storage system. The different design features of thermal storage systems are compared. Furthermore, some of the future work on the design of flexible-peak-shaving thermal storage system is also figured out. Finally, the design and practical application of molten salt heat storage system are prospected.