Abstract:As the issue associated with uncertainty optimization in essence, the handling methods for uncertain unit commitment are becoming more and more important as a large number of renewable distributed power generation equipments represented by wind power are integrated into power grid. Three different technology including stochastic programming, fuzzy optimization and chance-constrained programming based on scheme tree are analyzed just from the aspects of essential data, the complexity of the calculation, the dependence of parameters and the solving methods. Since any of the three kinds of technology has its own advantages, choice may be made according to the actual situation.

Abstract:The last breaker protection is usually installed in inverter station against the severe over-voltage caused by load shedding of AC system. A new last breaker protection design concept different from convention is adopted by ABB in ± 800kV Xiangjiaba-Shanghai UHVDC project. The comparative analysis of the last breaker protection in UHVDC and conventional HVDC projects is pursued with protection signal acquisition, protection logic, safety hazard etc. The limits of the last breaker protection designed in HVDC project and problems possibly occur in UHVDC project are pointed out. Finally, the corresponding suggestion is also presented. The study is helpful to improve the reliability of existing HVDC projects, and is useful for the operation and maintenance of future UHVDC projects.

Abstract:The mechanism of the steam-flow excitation triggered by nozzle governing is the main issue analyzed in the paper as steam-flow excitation phenomenon occurred frequently just after the reform of the turbine flow path in a 600MW steam turbine. According to the sequence valve test and bearing load calculation, optimization solution for steam distribution was achieved, and it was applied to steam distribution reform of the 600MW steam turbine unit successfully.

Abstract:Based on the detail analysis of An arc suppression coil accident of 35kV system caused by single-phase grounding, the suggestions about how to choose the damping resistance of arc suppression coil are proposed. And it can be used for actual reference.

Abstract:Anti-operation lockout is one of the important ways of ensuring safe operation in substations. In the initial operating stage of microcomputer five-preventing system in Pukou Power Supply Company, the phenomenon of empty procedures and manual setting actions in process of operation often appears. In order to reduce harmful accidents caused by anti-operation device, cause of abnormity is analyzed and improvement measures are proposed which are based on practical experience. And then the probabilities of manual intervention for microcomputer five-preventing system can be reduced, and the reliability of operation can be improved.

Abstract:With the continuously increasing scale of the power system, the short-circuit current of buses is consequently increasing. At present, the current-limiting inductor (series inductor) is often used to limit the three-phase fault current in 500 kV power system. The paper presents a new approach for optimal CLI location based on particle swarm optimization(PSO), to make the quantity and total impedance of CLI least and ensure power system normal operation in the premise of meeting short-circuit current limit. The practicability and reliability of the approach is verified by comparison with enumeration results of an IEEE 30-bus system. The approach has been applied to the Jiangsu Power Grid and met the design requirements.

Abstract:The various typical main circuits of high voltage frequency converters and input side harmonics as well as the characteristics are analyzed in the paper. The software PSIM has been utilized for the calculation of the characteristics after the theoretical analysis was carried out. The theoretical analysis and the corresponding numerical calculation are proved to be correct just with the actual data obtained through field tests.

Abstract:With the development of distributed generation (DG), planning of electric distribution system are confronted with new challenges. Considering of the increase of loads, an optimal planning model of distribution network is proposed to achieve multi-objectives which are consisted of minimum investment of DGs and transmission lines, and the minimum power loss of distribution network. Heuristic method is adapted to solve the problem by taking full advantage of distribution network's radial characteristics. And the impact on power system of DG is analyzed by the fuzzy evaluation algorithm. The objective function is optimized by introducing coordination coefficient. The results of test example prove the validity of the proposed model and algorithm.

Abstract:The insulation fault occurred between different slices of the iron cores will seriously affect the operation of the generators since the iron core is one of the most important components. With the experiments carried out on the iron cores, the faults can be detected more early to avoid the deterioration of the issues. The fundamental and specific operation methods of ELCID (Electro-magnetic Core Imperfection Detector) are introduced in the paper, and the detailed precautions analyzed with several examples are also proposed. The iron-loss tests are proved to be feasible for the judgment of the condition of the iron cores.

Abstract:Harmonic pollution is regarded as a serious damage to obstruct the development of power electronics. Twenty factories of Wuxi have been taken as samples to test their power harmonics and analyze the related situation. And some countermeasure to improve harmonic pollution is proposed. The study can be used for reference in controlling and preventing the power harmonic pollution of Wuxi power grid.

Abstract:At presents, medium and small hydro-power generator applies expanding unit connection mode, and stator earth fault protection cannot distinguish the failure unit, which leads to the tripping of all units and the enlarging of failure range. A novel selective stator earth fault protection based on zero-sequence direction element is calculated and analyzed. With the on-site experiment results, the validity and reliability of this principle is verified.

Abstract:In the calibration process of second grade standard platinum resistance thermometer's fixed point, the measure results will be affected by standard equipment, fixed point container and bridge for measuring temperature. This paper analyzes the impacts of these factors on uncertainty evaluation of calibration result. Based on the technical specification of 'Uncertainty Evaluation and Expression of Measuring' published in 1999, a new uncertainty evaluation method is proposed to assess the calibration results of Second Grade Standard Platinum Resistance Thermometer's triple point of water, freezing point of zinc and freezing point of tin.

Abstract:The period verification is an important measure to guarantee the measurement standards and instrument calibration, and the reliability of calibration status in the laboratory. The concepts, objects, methods and implements of the period verification are presented and discussed in this paper. The way of choosing appropriate and effective verification methods according to different objects is introduced. All these analysis results can provide technical reference for laboratory period verification.

Abstract:With the popularization of multi-service transfer platform (MSTP) concept, the traditional Synchronous Digital Hierarchy (SDH) equipments have been gradually replaced by MSTP products. The application of Ethernet transparent technology in MSTP system expands constantly in the power network operation level. The problems and characteristics of some applications of Ethernet in MSTP system are analyzed, and the suggestions are proposed.

Abstract:The electric power system is a complex non-linear dynamic system, which is composed with generation, transformation, transmission, distribution and load demands. There are some defects when traditional methods are utilized to analyze such a complex system. As a typical intelligent algorithm, the artificial neural network (ANN) technology has many advantages in solving non-linear problems, and it has been successfully applied in various areas of power system. The application of artificial neural networks in power system is introduced in this paper, including fault diagnosis, intelligent control, relay protection, optimization and load forecasting.

Abstract:Based on the planning target of smart grid and the developing map of smart distribution network, the new data communication network under smart grid environment is proposed. In this data communication network, OPPC (Optical Phase Conductor) is utilized as the transmission medium, passive optical network is used for transmission network, and IPv6 is applied as service interface.

Abstract:The soft-switching's technical features and objectives are introduced, and the network architecture and its working principles are also proposed in this paper. Technical issues of soft-switching network is analyzed, including device configuration, QoS, disaster recovery, NAT traversal of SIP protocol, security etc. Finally, the technical requirements for constructing network are presented.

Abstract:The relationship between the cleanness of tube inner surfaces and the flowing pressure drop is analyzed in the paper using the momentum equations for steady flow. With the actual data of oxide scale obtained during the period of maintenance and normal operation, the quantitative relationship between the pressure drop and the weight of oxide scales at the entrance of the economizer is proposed in the paper to provide measures for the assessment of oxide scales. The method can provide reference for the assessment of the cleanness of inner surfaces.

Abstract:In order to eliminate the so-called plaster rain phenomenon and to solve the unbalanced phenomena associated with the distribution of flow gas velocity and gas flow in the desulfurization demister, the technical reform program for the desulfurization demister was carried out in Guohua Taicang Power Generation Co., Ltd. during the period of maintenance. The reasons for the degradation of the demisting ability as well as the analysis of the demisting flow field and the technical reform program are introduced in detail in the paper.

Abstract:In order to reduce the emission of NO_x in the combustion system of a 480 t/h coal-fired boiler, the 8th furnace has been reformed using the technology of LP Amina. The emission concentration of the NO_x is about 262 mg/m³ with an obvious decline of almost 40% than before while the efficiency of the boiler has been improved. The objective of energy conservation and emission reduction has also achieved.

Abstract:Based on the detailed introduction of the working principle, the whole process of the cavitation erosion which is the main reason for the decrease of the service life of the water-ring vacuum pump system is analyzed in the paper. Two kinds of reconstruction schemes for the cooling water in the coolers and the working fluid in the vacuum pump are proposed, and the methods abandoned in the paper are also discussed to make a comparison.

Abstract:This thesis carries out detailed technical economical analysis on four make-up water treatment schemes for large-scale boiler with water source of medium and low salt content, namely "total demineralization system," "ultrafiltration plus reverse osmosis plus primary demineralization system plus mix bed," "ultrafiltration plus primary and secondary reverse osmosis plus mix bed" and "ultrafiltration plus primary and secondary reverse osmosis plus electrodeionization." Based on the analysis, the author has come to the conclusion that large-scale boiler make-up water treatment system with water source of medium and low salt content shall select "ultrafiltration plus extra-low pressure reverse osmosis plus primary demineralization system plus mix bed" scheme because of its excellent technical capability and moderate investment and operating expense. If the salt content of raw water exceeds 270mg/L, then "ultrafiltration plus reverse osmosis plus primary demineralization system plus mix bed" treatment scheme with superior technical and economic performance shall be chosen.

Abstract:As the important component of the thermodynamic system, the selection of the main feed water pump will not only affect the safety and efficiency of the whole plant, but also have great effect on both the initial investment of the construction project and the long-term production. The configuration of the main feed water pumps for different ultra supercritical power plants in China are introduced in the paper. The optimization of the selection of main feed water pumps for the ultra supercritical power plants adopted in the phase Ⅱ project of Shazhou Electric Power Co., Ltd. is also carried out.

Abstract:The Control Strategy, specific control methods and economic benefits achieved after the reform of the condensate pumps in 630 MW supercritical once-through power plants of Guohua Taicang Power Generation Co., Ltd. are introduced in detail in the paper to provide reference for other electric power enterprises.

Abstract:This paper introduces the application of the optical technology in the construction of strong and smart grid, which involves communication, sensor measurements, and utilization of new energy. Each application principle and prospects are specified in detail. The necessity of researching the optical technology in construction of strong and smart grid is mentioned.