The integration of large-scale wind farms will lead to transient stability problems, such as frequency offset, weak feedback and high harmonics, and affect the safe operation of the system. Therefore, research of transient protection technology for large-scale wind farm integration is an urgent requirement. A comprehensive review about grid connection technology and the transient protection technology for large-scale wind farms is carried out. The topology structure of each integration technology is carefully analyzed. Besides, the fault characteristics of three power systems, including permanent magnet synchronous generator, doubly fed induction generator, and traditional synchronous power system are compared and the current research status of transient based protection of onshore and offshore wind farms is illustrated. Finally, perspectives are outlined for future development of relay protection technology in large-scale wind farms, which provides a significant reference for the research of future wind farm integration.

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.

Aiming at the problem of weak internal regularity caused by the characteristics of nonlinear and strong fluctuation of load data, a TCN-WOA-BiLSTM-Attention power load short-term prediction model based on Bootstrap error correction was constructed. Temporal convolutional network (TCN) was used to extract temporal features and the contribution of important information to the features was highlighted through the Attention mechanism. The whale optimization algorithm (WOA) was employed to find the optimal bidirectional long short term memory network (BiLSTM) hyperparameters, thus to reduce the negative impact of manual search hyperparameters and then forecast. Based on Bootstrap analysis on error distribution of the prediction interval, the necessity of correcting the prediction result was judged by whether the PICP was lower than the corresponding confidence, and the reasonable correction range was selected. The results show that, the error correction based on the Bootstrap method can avoid the problem of insufficient correction and excessive correction. Compared with the method of correcting the whole error sequence, it is more scientific and improves the prediction accuracy of the model to the greatest extent.

With the increase of the scale of wind farms and the proportion of wind power in energy system, the power grid has higher and higher requirements for the voltage stability of wind farms. The actual operation status of wind farms is focused, and the key issues of the reactive power and voltage control of wind farms are summarized, including how wind turbines adjust the reactive power, how to allocate the reactive power in large scale wind farms, how to maintain the stability of the internal node voltage of wind farms, how to solve the problem of voltage control lag, the transient voltage control strategy under fault conditions, and so on. In view of these issues, the methods and characteristics of reactive power and voltage control technology in wind farms are systematically summarized, and the realization process of reactive power and voltage control technology is expounded from the aspects of the characteristics of wind turbines and reactive power compensation equipment, reactive power and voltage steady-state control, internal node voltage control, model predictive control, and transient control under fault conditions. The research can provide reliable technical means for safe and stable operation of wind farms.

As a critical component for capturing wind energy, wind turbine blades may subject different degrees of damage due to blade manufacturing and operating load, which directly affects the reliability of wind turbine operation. For preventing quality and safety accidents, a fast and easy non-implantable detection method is needed to identify the damages. According to the physical correlation between blade damage and blade operation noise, a blade damage detection method based on acoustic signal and convolutional neural network (CNN) is proposed. The method converts the time-series acoustic signal into a two-dimensional spectral picture and combines the healthy spectral picture to generate a residual spectral picture. Then, the residual spectrogram is used to train the convolutional neural network and detect the damage. The analysis results show that the algorithm eliminates the influence of the inherent blade sweeping sound generated by the impeller rotation on the damage identification and improves the identification accuracy. The algorithm analysis was carried out with the actual measured data of a local wind turbine, and the results showed that the classification accuracy of the algorithm reached 96.9%, which verified the effectiveness and accuracy of the detection method based on convolutional neural network.

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.

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.

Sensible heat storage is an effective way to solve the instability and fluctuation of solar thermal utilization. The common water medium was used as the medium material of sensible heat energy storage, and the heat storage tank device was used to realize the application of solar energy heat storage and release. The basic shape of the initially selected water tank was cylindrical. The conical structure of the tank bottom was optimized, and the respective heat storage change characteristics of the heat storage water tank under the three working conditions of 40°, 45° and 50° cone bottom angles were explored. Based on the unsteady laminar heat transfer model, the volume average temperature change and the maximum volume temperature change of the heat storage device were simulated by using the Fluent numerical software. The results showed that, when the cone bottom angle was 50°, the overall heat charging and discharging performance of the heat storage tank was better. When the average temperature of the heat storage tank body was 308.612 K under this parameter, the average temperature of the heat storage tank body was 0.202% and 0.053% higher than that of the heat storage tank body with a cone bottom angle of 40°and 45°, respectively. On this basis, the dynamic change law of heat storage and heat release of 50°tank was further analyzed, and the distribution characteristics of key indicators such as volume fraction and velocity field in the process of water storage and drainage inside the tank were studied. This research can provide some reference for the optimal design and engineering application of solar energy thermal storage system.

Based on the control difficulties in the operation process of the unit after the bypass heating alteration, a complete control strategy was proposed under the bypass heating condition, which realizes the bypass automatic control under the heating condition and meets the needs of the unit heating regulation at the same time. Aiming at the influence of bypass switching on and off and working condition disturbance on the operation stability of steam turbine under the heating condition, as well as the change of unit safety boundary, a set of logic design scheme including bypass blocking and overriding was proposed, which effectively guarantees the unit's safety and stability. Aiming at the changing characteristics of the steam turbine flow characteristics and the boiler's response to temperature and pressure characteristics in the state of bypass heating, an optimization strategy for coordination correction was proposed, which improved the quality of network-related control of the unit. The control scheme proposed in this paper has been applied in the supercritical once-through furnace unit. It has been verified the control strategy can realize the automatic control of the bypass system, and the control effect of the coordinated variable load is good. After the bypass RB acts, the unit can transition smoothly, realizing the bypass supply Automatic and safe control of the unit under thermal conditions.

With the structural upgrading of China's energy industry and the transformation of economic growth mode, clean energy power generation technology has been continuously and rapidly developed. As a high-power electric heating conversion device, electric boiler has become one of the effective technical solutions to enhance the operational flexibility of thermal power units and promote the reliable consumption of new energy power. In this paper, the allocation and accounting principles of electric boiler capacity and heat storage capacity in such projects are proposed. The calculation model of system optimization operation parameters and operation economy evaluation is established based on the principle of maximizing the economic benefits of enterprises, taking into account the factors of grid peak shaving depth dispatching limits. Combined with the actual situation of the multi-unit system of a thermal power plant in Northeast China, the optimal configuration capacity of the electric boiler of the project is 300 MW, and the heat storage capacity is 17 MW·h. At the same time, the optimal operation scheme of the whole plant is proposed. The results show that, under the condition of 30% peak shaving depth limit, the case power plant can add about 139.53 million Yuan in each heating season, and the project investment payback period is about 5 years. In the foreseeable future, the project will have long-term profitability.