Papers by Keyword: Monte-Carlo Method

Abstract: Voltage sag assessment of distribution network with DGs based on Monte Carlo method is researched in this paper. Models of synchronous machine type DG and inverter type DG are established respectively; then a typical distribution network with DGs is simulated based on PSCAD/EMTDC. Impacts of type, control strategy, output power and location of DG on voltage sags are discussed based on several simulation examples. The results show that inverter type DG has certain capability of suppressing voltage sags and can reduce the frequency of voltage sags in distribution network and the impacts are depend on its type, control strategy, output power and location.

Abstract: Considering the uncertainty and randomness of casing loadings and geometry sizes, performance parameters in deep wells, a kind of calculation method of probability distribution of casing external loading and collapse strength was established. Based on the Monte-Carlo method, the probability distribution of casing strength was simulated under non-uniform external loading conditions. With strength-load interference theory, the calculation method of casing safety reliability was obtained, which can analyzes reliabilities of different types of casing strings subjected different loadings in the dangerous section, and a regional relationship between casing reliabilities and safety factors is established. Results show that when casing reliabilities collapse strengths are in the range of 0.5-1.0, the related safety factors locate from 1.0 to 1.25. Safe reliability analysis can provide references for casing strength designs in deep and super deep wells.

Abstract: For low order process with large time delay, a kind of optimal PI controller tuning method is proposed based on generalized Hermite-Biehler theorem and Genetic Algorithm. Firstly, the stable region of PI controller is obtained by using the generalized Hermite-Biehler theorem. Then the optimum parameters are selected from this region based on ITAE criterion and genetic algorithm. A tuning formula is obtained by nonlinear fitting of optimization result, which has the capability to cover the variety of normalized time delays up to 100. Simulation of Monte-Carlo stochastic experiment indicates that the proposed method has good performance robustness when parameter uncertainty occurs, compared with other four PI tuning methods.

Abstract: Pre-estimate of hydropower project investment risks is of much importance because of the huge economic loss caused by the negative effects of the risk factors. Components of cash flow of hydropower project investment and finance evaluation are presented to study the effect of investment risk variables on hydropower project based on the structure of hydropower project investment and benefits. The project investment risk and index are evaluated by the simulation technique, which provides a basis for scientific decision-making of the project.