Owing to the late development of offshore wind power in China, operational data and maintenance experience are relatively scarce. Due to the harsh environmental conditions, a reliability analysis based on limited sample fault data has been regarded as an effective way to investigate maintenance optimization for offshore wind farms. The chief aim of the present work is to develop an effective strategy to reduce the maintenance costs of offshore wind turbines in consideration of their accessibility. The three-parameter Weibull distribution method was applied to failure rate estimation based on limited data. Moreover, considering the impacts of weather conditions on the marine maintenance activities, the Markov method and dynamic time window were used to depict the weather conditions. The opportunistic maintenance strategy was introduced to cut down on the maintenance costs through optimization of the preventive maintenance age and opportunistic maintenance age. The simulation analysis we have performed showed that the maintenance costs of the opportunistic maintenance strategy were 10% lower than those of the preventive maintenance strategy, verifying the effectiveness of the proposed maintenance strategy.

The maintenance costs of offshore wind turbines operated under the irregular, non-stationary conditions limit the development of offshore wind power industry. Unlike onshore wind farms, the weather conditions (wind and waves) have greater impacts on the operation and maintenance of offshore wind farm. Accessibility is a key factor related to the operation and maintenance of offshore wind turbine. Considering the impact of weather conditions on the maintenance activities, the Markov method and dynamic time window are applied to represent the weather conditions, and an index used to evaluate the maintenance accessibility is then proposed. As the wind turbine is a multi-component complex system, this article uses the opportunistic maintenance strategy to optimize the preventive maintenance age and opportunistic maintenance age for the main components of the wind turbine. Taking the minimum expectation cost as objective function, this strategy integrates the maintenance work of the key components. Finally, an offshore wind farm is taken for simulation case study of this strategy; the results showed that the maintenance cost of opportunistic maintenance strategy is 10% lower than that of the preventive maintenance strategy, verifying the effectiveness of the opportunistic maintenance.

To solve the problem of grid-connected control of differential speed-regulating wind turbines, the wind turbine, transmission chain, speed-regulating motor, and generator model of the unit are constructed using the MATLAB/Simulink platform. The differential speed-regulating control system is designed on the basis of slip-frequency and fuzzy control theories. The speed control function and characteristics on maximum power tracing of wind turbine is tested via simulation. Meanwhile, the experimental bench for the differential speed-regulating wind power system is set up. Test results indicate that the generator speed is controlled by speed-regulating motor with output voltage and frequency that are approximately synchronized with those of power grid under idle load condition. The maximum wind-power utilization coefficient is maintained by fuzzy controller under the rated wind speed. Thus, the accuracy and efficiency of the designed control system is proven and provide important implications for further investigations on the grid-connected control of wind turbines with differential speed regulation.

China is facing a number of challenges, such as environmental pollution, energy security, and slowing down of economic growth. China's total energy consumption has been leading the worldwide consumption for several years. China's annual primary energy consumption accounts for more than 90% of total energy consumption, and the country's utilization of wind energy, solar energy, biomass energy, and other new form of energy remains very low. This research has adopted a strength, weakness, opportunity, and threat (SWOT) analysis approach to examine the internal and external factors that affect the competitiveness of the energy industry in China. An extensive and critical review of a wide range of literature was conducted, including academic papers, industry reports, statistical data, relevant regulations, and policy documents. Eighteen factors were identified from the literature review. These factors form part of an integrated framework that provides a useful tool for policy makers and the industry to gain a better understanding of the factors that affect the sustainable development of the Chinese energy industry. The results also provide a useful reference for foreign firms that intend to explore the Chinese energy industry market.

Numerous problems have emerged with the rapid development of wind power in Xinjiang. The predominant problem is the inhibition of the healthy development of the wind power industry by wind power curtailment in Xinjiang. In this study, wind power heating and high energy-consuming industries were coupled to increase wind power consumption in Xinjiang on the load side. The feasibility analysis of wind power heating in Dabancheng showed that the heating load characteristics coincide with the wind characteristics and the electric heating technology can fulfill the requirements for wind power heating. A business model innovation achieved a win–win situation. Furthermore, a wind power heating system was designed in Dabancheng, the boiler capacity and the heat storage capacity were calculated, and a heating system model with heat storage technology was established. Wind power heating with heat storage can improve the consumption of wind power and increase the local electric load and system adjustability. Furthermore, heating with curtailed wind power can save 2942 tons of standard coal as well as reduce 5172 tons of CO2, 2.9 tons of SO2, 22 tons of NOX, and 2 tons of soot emissions. Non-grid-connected distributed wind power was applied to the high energy-consuming coal chemical industry to reduce wind power curtailment, expand the consumption market, and reduce pollution. A multifunctional wind-photovoltaic complementary system with hydrogen energy storage coupled with traditional high energy-consuming coal chemical industry was established. The implementation plan using wind and solar energy to produce, store, and apply hydrogen energy was proven beneficial. Wind power consumption was improved on the load side. The wind power curtailment problem was reduced by increasing local load using the curtailed wind power to provide clean heat in Dabancheng and constructing the multifunctional wind–photovoltaic complementary system. This study will contribute to the healthy and sustainable development of the wind power industry in Xinjiang.