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This paper presents wind energy conversion model, drive shaft’s dual-mass model and generator’s transient mathematical model for the transient analysis of fixed speed asynchronous wind generators, and analyzes the transient characteristics of the wind generators under the condition of low voltage fault. The control principles of two dynamic reactive power compensation equipments as static var compensator (SVC) and static synchronous compensator (STATCOM) are introduced. Take a wind farm consists of fixed speed asynchronous wind generators as an example, the two compensation equipments are simulated in PowerFactory/DIgSILENT to compare the effort of them on enhancing the low voltage ride-through capability of the wind farm.

This paper analyses and studies control of nitrogen on Al- killed steel using the methods of production experiment in the flow of molten iron pretreatment - 180t converter - LF refining – continuous caster. Results show that adding aluminum final deoxidization should be divided into two steps: Firstly, putting some aluminum into molten steel after adding alloy in the process of tapping of molten steel, making the [O] reduce to 6 ~ 7ppm. Secondly, adding aluminum wire in LF-refining making [O] and [N] reach the required values. LF-refining should try to shorten operating time and original mission ought to be finished ahead. Desulfurization should be completed in the flow of molten iron pretreatment and the tapping of molten steel. Process of removal inclusions should be accomplished by adding slag during tapping of molten steel and blowing-mixing. LF-refining has scarcely any slagging task, it only needs to complete adjustment ingredient task. Alloy and carburant which contains extremely low nitrogen should be choosed, so that nitrogen in molten steel can be steadily controled below 30ppm.

Considering the probabilistic of the wind power and the solar power, a fault recovery method for distribution systems with the wind power and the solar power is presented in this paper. For the wind power, a simplified steady-state equivalent model of an asynchronous wind generator is added into the Jacobian matrix to consider the impact of the wind power on systems. For the solar power, its output is considered as an injected power which is related with solar irradiance. Three-point estimate is employed to solve the probabilistic power flow of distribution systems with the wind power and the solar power. The restoration is described as a multi-objective problem with the mean of the system loss and the number of switch operations. Fast elitist non-dominated sorting partheno-genetic algorithm is used to solve this multi-objective problem. IEEE 33-bus system is used as an example and the results show that the models and algorithms in this paper are efficient.

With the wind power increasing quickly, its impact on power system becomes greater, thus the dynamic simulation study on grid-connected wind power generators has a significant importance. This paper focuses on introducing the quasi-steady-state approximation method into analyzing the operation characteristics of grid-connected doubly-fed wind power generators. Based on the detailed dynamic model of a variable-speed constant-frequency (VSCF) doubly-fed wind power generator, which consists of wind speed model, the integrated model of wind turbine and drive system, pitch angle control model, converter control model, and the integrated model of generator and converter, the quasi-steady-state approximation method is introduced and applied to simplify the detailed dynamic model to be an order-reduced model, that is, the quasi-steady-state (QSS) model. The accuracy of the QSS model is shown by comparing simulation results of QSS model and the detailed model.