Abstract:Based on the traditional power planning, this paper proposed a micro-grid generation expansion planning model under the conditions of low-carbon economy, taking the Clean Development Mechanism (CDM) and also carbon constraints and carbon trading into account. An improved matrix real-coded genetic algorithm was adopted to solve the model, and by enhancing the operator of genetic algorithm, the global optimal solution was obtained reliably and the convergence speed was improved. Results show that the proposed model and algorithm are reasonable and effective.

Abstract:According to the basic principle of Heat Quantity Method, a thorough research on the ratio of heat-supply indices and the statistical calculation method for the complicated heating system of large scale power generation unit were conducted in this dissertation. Having put forward the boiler heat output-based heat-supply definition formulas, a simple calculation method was then obtained for the daily statistics of power plants. This paper also discussed the applicable conditions of the ratio of heat-supply definition formulas under the industry standard, and statistical specification on unit heating load, which had positive guidance meaning for the occupation standard of heat-supply indices.

Abstract:The tripping operation of the 35 kV back-up protection of the 110 kV main transformer is analyzed in the paper, which caused by the B-phase grounding in II section of 35 kV bus in 110 kV substation. Based on the substation equipment parameters and the actual fault wave in the protection, the hypothetical reasoning and inversion analysis of short-circuit fault current are carried on. The cause of the accident is that the voltages of other two phases rise, resulting in the overall insulation deterioration, which caused the nonmetallic three-phase short circuit fault at last. However, as there is no current transformers in B-phase of 35 kV system, so the B-phase grounding fault cannot be detected. Thus, the 35 kV back-up protection operation behavior in 110 kV main transformer is confirmed to be correct. Finally, suggestions for improvement are also proposed.

Abstract:Vibration failure occurred to one 600 MW steam turbine after the scheduled maintenance. Large vibration was discovered at 3X and 5X during operation duration, while 2 times frequency components were found during deceleration process at No. 4, 5 and 6 tiles. According to the maintenance and dynamic process, the mentioned issues are analyzed in the paper, and mass unbalance, insufficient force on bearing and misalignment of coupling are believed to be the main reasons. This problem has been successfully solved through dynamic balance method and enhancing bearing force.

Abstract:The paper analyzes the reasons for malfunction of transformer differential protection in external fault, which caused by zero-sequence current. Based on the differences between RET670 and RET521 of ABB in eliminating zero-sequence current, a method of start value calculation for RET670 in differential protection debugging is established. Finally, results show that, RET670 should apply the cross blocking scheme in restraining inrush current, and it can improve the sensitivity in single phase to ground internal fault. However, compared with RET521, RET670 has relatively low sensitivity in phase to phase fault.

Abstract:When overvoltage situation appears in capacitor bank, the traditional definite time overvoltage protection will cut off the capacitor bank in an appointed time delay, which makes the equipment margin of capacitor bank not be fully utilized. This paper gets the inverse time characteristic equation of overvoltage protection by curve fitting on the basis of the data from relevant standards. The inverse time overvoltage protection of capacitor bank is realized in a microprocessor-based protection device according to this characteristic equation, and it has achieved better results in practical application.

Abstract:Based on the voltage and reactive power hierarchical idea, according to the principles of three-stage voltage control mode and the hierarchical management feature of regional grid, a coordination control solution of the AVC (automatic voltage control) system for region and county grid was proposed. The principles of the coordination control were elaborated. And control strategies were discussed respectively for region and county side. At last, actual applications in power grid show that the proposed technical solution and control strategies are feasible and effective.

Abstract:The successful applications of electronic instrument transformer in digital substation can give references for electrical auxiliary system of power plant in resolving the shortcomings of traditional instrument transformer. In order to promote the electronic instrument transformer's applications in the electrical auxiliary system of power plant, this paper discusses the traditional transformer's shortcoming, electronic transformer's merit and application mode, digital protection measurement device and etc.

Abstract:In the low voltage distribution network, most of actual load is inductive load. Besides, the principle of reactive power compensation is only use capacitance instead of inductance, but the electric capacity between each phase is limited. Considering these facts, the paper proposed an all-capacitor adjusted compensation model taking minimal loss as the optimization goal based on time-vector method. Furthermore, simulation results verified the theoretical accuracy of the proposed model. And the model showed its superiority over traditional compensation methods.

Abstract:According to the integration and modulation requirements of data acquisition, transmission and control, a new-type distribution terminal based on open terminal design idea is proposed, which can be installed once and expanded repeatedly. And the technology would promote the distribution terminal progress in opening and expansibility. Results show that the new-type distribution terminal has complete functions, stable performances, better economy, and it can fully meet the needs of distribution system automation.

Abstract:In order to improve the accuracy of load forecasting, a combined forecasting method has been introduced in this paper, which can obtain more accurate results through combining the advantages of single prediction models. Two parameters are introduced so that the combined model can be transformed into extreme value problem and solved by evolutionary programming. At last, the combined forecasting model and single models are used to calculate the historical power supply and maximum load of Yancheng city zone. By comparing the results, it is easy to find that the error of the combined model is less than that of any single model. Furthermore, the combined method is applied to mid-long term load forecasting.

Abstract:Breaker operating circuit plays an important role in the breaker operation system. And its main function is to issue the circuit breaker tripping and closing pulse, prevent breaker "jump" phenomenon, and monitor on the status of breaker tripping and closing circuit. A reasonable designed operating circuit can effectively improve the reliability of the breaker operation. This paper describes the functions of breaker operating circuit and the main part of the circuit. Furthermore, a practical solution and its application for the issue of the trip circuit monitoring are proposed and discussed.

Abstract:The successful application of RCS-985R/S microprocessor-based protection in 160Mvar synchronous compensator in Anding substation was introduced in the paper. Besides, the start manner of synchronous compensator, the protection configuration and operation were analyzed in detail. And the protection functions which are different from that of conventional generator were described significantly.

Abstract:In view of current and voltage transformer's field error detection work, this paper introduces detection conditions of transformers, and puts forward error detection circuit and wiring method for current and voltage transformer. Besides, the main influencing factors of transformer's field error detection are analyzed in detail. The results process method of transformers' field error detection is also pointed out. Proposals and measures for transformer's field error detection are put forward, which have reference value for transformer's field error detection work.

Abstract:Multilevel SVG has been researched and used widely because of its lower output harmonics and high power capability. A new topology of multilevel SVG is presented in this paper. The new topology achieves comprehensive compensation of reactive power, harmonics and three phase imbalance using two inverters with common DC capacitor. The structure and compensation principles of the new multilevel SVG are analyzed. And the main circuit and control circuit of hardware are designed using DSP and FPGA as the core of the system hardware. The design of software is introduced, including main program, the timer interrupt subprogram and FPGA module. Lastly, results of simulation and experimental verify that the proposed system has good effect in reactive power compensation and the voltage of DC capacitor is stable.

Abstract:Based on the analysis of the low voltage short testing, the percentage of short-circuit impedance was proposed to checking capacity of 110 kV transformer. And the method is suitable for checking the national specification transformer. Lastly, the proposed method is verified feasible through the capacity checking test of two 110 kV transformer.

Abstract:The paper introduces the IMS architecture and the service model of policy-based Quality of Service (QoS). And the management mechanism of dynamic QoS and service level agreement (SLA) is also described. Through the simple SIP signaling, information security management system (ISMS) can achieve the SLA re-negotiation between users and service provider, thus it can ensure the dynamic QoS implementation of service transport in IMS.

Abstract:The architecture of dual WEB servers,methods of data synchronization and mechanisms of service IP switching are discussed in this paper based on the practical application of the Energy Management System in Nantong district dispatching center. Application results show that these mechanisms reliably ensure the synchronization of real-time data, power system model and historical data in the dual WEB servers at area III with those at area I and the configuration of dual WEB servers ensure the stable information browse service.

Abstract:Commissioning test is important to ensure the reliability and security of substations. If malfunctions occur when a substation is running, they will leave substations hidden dangers to the electric grid. This article analyzes the problems found during the commissioning tests of three substations. Based on the results of the experiment, suggestions are proposed to avoid similar troubles.

Abstract:Due to the low space requirement, large storage ability and excellent environmental performance, circular coal storages are believed to be widely accepted in the future. However, the application has been limited seriously by the high cost. It's necessary to optimize the structure so as to make the cost much lower. The feed patterns of coal including high location and low location modes are the critical factor influencing the cost, thus, a more appropriate layout was recommended in the paper after a comprehensive analysis on structure, arrangement and characteristics.

Abstract:During the operation of pulverized-coal fired boiler, essential combustion adjustments are required for the boiler to maintain good operation performance and low concentration of NO_x emission when coal quality and other factors change. Operation personnel can evaluate the impacts of the variations of the factors and the corresponding adjustment measures based on the unit performance and their operational experience so as to determine the better mode and extent of the adjustment needed. The commonly used methods for the prediction and control of boiler NO_x emissions during power plant operation mainly include the empirical method based on combustion tuning tests, the mathematical model method based on optimization control and the method based on CFD simulation and performance analysis. Based on the review on the current status of the investigation and application of boiler NO_x emission prediction and control, CFD technology was applied for the numerical investigation and performance analysis of the boiler with advanced combustion system to realize the goal of safe, stable, highly efficient and low-NO_x operation of the boiler.

Abstract:An infrequent fracture failure of T92/HR3C dissimilar steel welded joints of an USC final superheater was analyzed by hardness distribution and microstructure. Meanwhile, manufacture process and equipment operating conditions were investigated. The results indicate that post welding heat treatment process has a great influence on the weld line, the microstructure and mechanical property of T92 steel. The relevant suggestion was put forward to strictly control post welding heat treatment process. The microstructure of the heat-affected zone in the side of T91/T92 should be analyzed, and the micro-hardness test for the welded joints should be performed as well.

Abstract:The important role of tap parameters in power system operation and stability analysis is analyzed, and a development method of transformer tap real-time database system is presented on .NET Framework platform. After analyzing the description of transformer tap with the Common Information Model (CIM), a data storage structure of transformer tap is designed, in which the dynamic storage of real-time data is achieved by the ADO.NET data access methods and standard SQL statements.in Oracle database. Besides, web applications are developed using ASP.NET, the data of which bind with the Extensible Markup Language (XML) data files, so the transformer tap real-time database system is accessible in B/S mode.