Advanced Materials Research Vols. 860-863

Abstract: Large coal-fired power unit is a complex nonlinear system with more uncertainty to address, evaluate and optimize. It is essential and difficult to determine the key features contributing to the energy consumption of power units, especially considering the varying boundary constraints, operation conditions and system characteristics. In this paper idea of big data analytics is employed to clean the historian operation data efficiently and select the key energy-consumption features with less information losses. The result shows that the resultant key features reflect the exterior factors and system behavior. It makes great reference for the modeling and optimization of large thermal power units.

Abstract: This paper presents an intelligent method of optimized control of DC voltage based on BP Neural network, on account of this presentd method, by collecting parameters of grid voltage and significant frequency of harmonic current, then, construct couples of tranining samples and fully use the advantages of BP Neural network that can discretionarily utlize arbitrary precision to approximate any continuous function, and computing the optimized voltage of DC side, as a result, achieving online adjustment of capcitors voltage at DC side. Futher more, adjusting the hysteresis width automatically according to the voltage variation of capacitor, thus the voltage of DC side can automatically adapt to fluctuation of grid voltage and load current, so that to obtain comprehensive optimum of power loss and compensation performance of power active filter.

Abstract: The Smart power meter system based on ZigBee technology is successfully developed in the paper. The EM250 SOC chips are adopted to develop the wireless communication modules with ZigBee protocol. Parsing the AT command, encryption and such more basic function, the two different and independent program framework for the ESP and IHD(In-Home Display) have been worked out except finishing the data transmission. A smart wireless network based on ZigBee has been established. The home and outdoor testing have also been implemented too. The measured results show that a coordinator can support more than 500 nodes and communication distance reach more than 1000 meter outdoor and more than 50 meter from home to outdoor through the two walls.

Abstract: With the power system of China continuous expanding recently, the electric power generation, transmission and supply capacity increased dramatically. In order to improve economic operational efficiency and realize scientific development, the Input-Output efficiency between the input of the power system facilities and the output of the power supply becomes a critical issue that government, business and academia have to face up to. In this paper, we used the DEA (Data Envelopment Analysis) model and tested the Input-Output efficiency of power system development and study the trend of important development segment. The relative efficiency of power system is closely related to the electricity management system and economic situation, the elements of reduce the efficiency were been found out by analyzing the DEA results. And a series of suggestions were proposed to increase the comprehensive efficiency.

Abstract: The reliability assessment of power system components is the key to power system safe and reliable operation. According to the record of actual operation of power system components characteristics, a practical method of reliability evaluation for fault date which is missing components is introduced in this paper. The method is based on Weibull distribution model. It is also a calculation and solving methods of reliability evaluation fault system of missing data components. The system mainly includes sample selection of data, parameter calculation, model checking and failure rate curve drawing. So the transformer as an example, verify the effectiveness of this method. In addition the paper analyses the influencing factors in the transformer reliability, such as voltage grade, manufacturer and product types. In a word, this model provides a systematic and effective method for the practical application of the reliability evaluation of the electrical components.

Abstract: A novel method for power quality disturbances classification is presented using modified S transform (MST) and decision tree. The time-frequency properties of power quality disturbances are analyzed and the effects of window-wide parameter g on the properties are discussed. Four statistical features are extracted from the MST module time-frequency matrix and a decision tree is utilized to recognize 9 power quality disturbances. The simulations are made to illustrate the validity of the method proposed for power quality disturbances recognition.

Abstract: Industrial and agricultural production as well as the general public because the demand for is much larger, the electricity grids integrated-transportation network multiple transformer output to the end-use equipment bring great difficulties and many other different failures, resulting in a lot of energy wasted . This article is mainly to use the thyristor controllable series compensated (short for TCSC) for power during transmission of some compensation to make the system voltage stabilized and improved, combining with active power filter (short for APF) will suppress and filter out a series of primary and secondary synchronization harmonic interference etc. not only improve the effectiveness and utilization of electrical energy, but also purify the electricity grid environment. By the simulation results show that the power to improve the stability and quality are very good results.

Abstract: According to key values and demands of smart distribution grids in China, a smart distribution grid comprehensive assessment index system and method is established. The index system is divided into the demand index set and assessment index set. As the former represents the macroscopic features while the latter represents the microscopic factors of the smart distribution grid. A causal connection exists between them. Also a hierarchical optimization model with combination weight, which is based on the DEMATEL-ANP-anti-entropy weight method and the improved Grey incidence approach, is proposed. The DEMATEL-ANP-anti-entropy weight method is used for demand indices weight analysis, while the improved Grey incidence approach is put forward for the evaluation on assessment indices. Results of applying the proposed method in practical case shows that the proposed method is valuable in following aspects: scientifically assessing the intelligent development level and effectiveness of distribution grid, analyzing and recognizing the grids operation condition and weak link, giving reference to planning and construction of smart distribution grid, and so on. Index Terms Smart distribution grid; comprehensive assessment; index system; combination weight; hierarchical optimization.

Abstract: At present, the technology of wind power forecasting isn‘t mature enough in china, so some grid-connected wind farms will be assessed when theirs power forecasting accuracy cant reach the assessment standard. In response to the situation, combined with the characteristics of WPSPS and wind farms, this paper designs a service mechanism that WPSPS help wind farms tracking generation schedule curve, namely, encouraging WPSPS to supply output compensation service for wind farm by market means to increase the accuracy of wind power forecasting. By this mechanism, not only WPSPS and wind farms will achieve win-win, but also the impact on the grid caused by fluctuations of wind powers output will reduce.

Abstract: In order to improve the level of automation and security of the low voltage power supply system, this paper proposed the calculation method of short-circuit current criterion under condition of protection action. Firstly, the impact of circuit breakers on the short-circuit current is analyzed. Then, the current criterion under condition of short-circuit protection are given. Finally, using a special case, the calculation process of aforementioned current criterion is given in detail.