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For energy shortage and environmental problems, many nations and regions take greater action to develop new energy. China has also issued a series of policies and regulations to support the sustainable development of new energy, especially in wind power and solar. With the rapid development, problems such as how to objectively evaluate the implementation value and the effect of wind power and solar efficiency project become prevailing. However, most of the existing researches evaluate the project with single method schema, but lacking of systematic and comprehensive analysis. In this paper, with introducing the multi-level index system of the relevant participants we summarized and proposed a comprehensive evaluation method for wind power and solar operation, which combines the advantages of three different methods, i.e. analytical hierarchy process (AHP), entropy method and grey relational analysis (GRA). Based on the actual data from the eleven provinces in China, we analyzed the wind power and solar operation through these four methods. The results show that the method we proposed makes a full play to the advantages of each one and processes high efficiency, rationality and objectivity. And it can provide scientific evaluation and theoretical reference for decision maker in wind power and solar efficiency projects.

In the last few months, off-grid accidents of a large number of wind turbines in several large-scale wind power bases frequently occurred during the windy weather, severely threatening not only secure operation of wind farms but also secure the stable operation of power grid. This paper analyzes the cause of the “2.24” large scale wind turbines off-grid and other accidents, having found some common problems of the existing wind farms: firstly, almost none of wind turbines in operation has the low voltage ride through (LVRT) capability; secondly, dynamic reactive power compensation devices are functionally in-complete and chaotically managed; thirdly, poor construction techniques and equipment in-stallation are found in wind farms; fourthly, the main control system functions of wind turbines haven't been unveiled to users, and their coordinated control strategies do not meet the requirements, which demand wind turbines keep on-grid during grid voltage instantaneously drop; fifthly, all 35kV (10kV) systems in wind farms are not grounded, in which the single-phase grounding can quickly develop into phase to phase or three-phase fault to exaggerate the accident. Besides, the small current grounding line in 35kV systems is not reliable. In the current situation, this paper proposed countermeasures how to prevent large-scale wind turbine off-grid accidents, generally speaking, rectifying wind turbine LVRT capacity, refreshing wind turbine protection programs, opening reactive power regulation function of wind turbines, optimizing small current grounding line as well as improving the functions of dynamic reactive power compensation devices and strengthening the management of use, etc.

Wind power abandonment is the energy wastage caused by the fact that the wind farm can't take full advantage of wind energy due to failure of wind turbines or power grid congestion, etc. The indicator of abandoned wind power is important to the evaluation of wind farm operation management and the power grid dispatching, as well as the power grid planning and construction. But it is difficult to calculate the abandoned wind power, due to the difficulties of identifying the ought-to-be power generation under specific condition. Therefore, there are no standard calculation methods at home and abroad. In this paper, the definition of abandoned wind power and several calculation methods are proposed.