Abstract:The database solution for WAMS which is integrative utilization of commercial relational database and business time series database is proposed in this paper. Combined with the data characteristics of WAMS, the demands for Data Storage is discussed, the characteristics of two types of database are also compared. This scheme not only plays the advantages of the two databases, but also sufficiently meets the requirements of real-time, mass and safety and efficiently improves the convenience for data sharing in control center. The validity of this scheme has been verified by practical engineering applications.

Abstract:Application of modular multilevel converter (MMC) in VSC-HVDC is introduced, and varies of multilevel schemes are compared. This paper induces the HVDC control scheme for modular multilevel converter, and a suitable control strategy for MMC in HVDC system is proposed, which is verified by using dynamic model with test results. The results manifest that the control strategy is helpful for the stable operation and satisfy the basic control function requirements of HVDC.

Abstract:Security is an important approach to promote delicacy management of daily dispatch scheduling. Based on analysis of the needs of security checking and design of overall function, in accordance with three master line design which includes data flow center, process control center and data display center, power balance method and plan topology analysis management method based on predictor-corrector thcenology to form daily schedule power flow, and implement security correction adjustment based on the security constrained economic dispatch (SCED) algorithm after out-of-limit. The calculation speed and accuracy of system for security checking is proved by practical example.

Abstract:A practical example of an 110kV main transformer differential protection malfunction caused by the increase through currents in 1OkV line fault with error setting of wiring group is introduced in this paper. The reason of disoperation and eror seting is analyzed. Improvement method is put forward in order to prevent such situation in practical work.

Abstract:The reasons of the accident that low voltage side backup protection acting and the three-side switch tripping of main transformer caused by line protection crash and low-side switch hoops burned are analyzed in detail, according to the signals from monitoring system, the action of relay protection, the record of fault wave and the examination of electrical main and secondary equipment. The damage of some equipment and the signals from the protective devices are also analyzed. The defects of equipment operation and design which revealed from this accident are summarized, and the related suggestions are given.

Abstract:On basis of the steady characteristics and the control patterns of high voltage direct current (HVDC) transmission system with voltage source converter (VSC), a mathematical model is built for power flow calculation of VSC-HVDC, which use Newton method, simplified Newton method, third-order convergence Newton method and six-order convergence Newton method respectively for power flow calculation. Results from simulation prove that the algorithms are effective for various kinds of control patterns of VSC-HVDC. Calculation speeds of each algorithm are also compared. Based on those simulation results, two hybrid algorithms are proposed and simulated to verify their superiority.

Abstract:Static Var Compensator (SVC) can provide voltage support and improve voltage stability of power system. The additional damping control of SVC can improve the system's damping state to inhibit low-frequency oscillation. But there may be certain interaction between the two functions. The interaction between SVC voltage stability control and inhibiting of low-frequency oscillation in the one machine-infinity bus system is studied theoretically in this paper. Research shows that contradiction exist between SVC damping control and voltage control, enhance the system damping oscillation ability will sacrifice voltage quality. At last, a simulation using two-area four-machine system as an example, which verifies the SVC can effectively improve the voltage stability, adding additional controllers to effectively improve the system damping ratio, but the voltage stability becomes worse. The results and the theoretical analysis are consistent.

Abstract:It is necessary for analyzing and comparing the configuration scheme of with or without merging unit in smart substations based on practical engineering situation. Good energy efficiency and low engineering cost can be achieved because of a good configuration scheme. Due to the smart situation which applied conventional mutual inductors to sample, the advantage and shortage of the two schemes for merging unit are compared. According to the different locations of merging unit in smart substation, the influencing factors of with or without merging unit are illuminated. Finally, the detailed technical and economic index comparison of the two schemes are given based on a construction project of smart substation, and the reasonable suggestions on the choices of with or without merging unit are put forward.

Abstract:In order to reduce the impacts of electric actuator on the mechanical device when starting and control the start of the high torque electric actuator, a soft starter device for three-phase AC asynchronous motor based on AVR ATmega128 as control core and thyristors as voltage adjustable element is proposed in this paper, then the hardware composing and software designing of the device are analyzed. The results that the soft start designing is correct and soft starter device could achieve the effect of control motor stator voltage are shown by the experiments.

Abstract:There are two 120MW generators, which with resistor connected directly between generator neutral and ground, in YL hydropower station in Sichuan province, China. The voltage injecting stator earth fault (SEF) protection is in common use. However, it can't be directly used in the generators in YL hydropower station, because the terminators of the injection voltage source can't be connected directly to the grounding resistor, which probably with high voltage when SEF occurs. A new scheme of SEF is presented, and it is verified by the experimental results. The relative errors of measuring results of earth fault resistors are not greater than ± 5%. Moreover, the high voltage grounding resistor is reserved and the engineering cost is reduced.

Abstract:The security and stability control system is the important guarantee of power system. Based on the geographic connect graph of northwest power grid of Yinchuan-Shandong DC system, this paper analyses the serious problems of security and stability, and introduces the configuration and main function of security and stability control system, the characteristics of control system are also summarized. The result of local combined adjusting indicated that the introduced stability control system can guarantee the safety and stability of northwest power grid of Yinchuan-Shandong DC system.

Abstract:The enterprise can avoid peak electricity and save electricity costs through optimizing load operation mode with tou price. Important factors that affect optimal load running in production process are introduced. The load optimization model based on tou price is built. Heuristic method for solving is proposed in this paper. The example shows that load optimal operation model and its algorithm based on tou price are realistic and have the practicality.

Abstract:The problems exiting in measuring tools delivery under the actual operation of the measuring center are discussed. In the view of the situation that measuring center has a lot of secondary level warehouses, all of which are distributed in whole province, and need to be delivered uniformly, how to apply the mathematical model of the single-parent GA algorithm for measuring center is discussed. The comparison shows that the single-parent GA algorithm could achieve good results on measuring tools delivery of measuring center.

Abstract:Some key problems in the realization of RTU sequence operation are introduced, this paper gives the design scheme of RTU devices as station level centralized sequence operation server definition and its transmission, naming and using of operation order number, execution of operation, process information interchange, implementation of anti-operation lockout, and operation rehearsal, remote communication process details are also designed. Combined with engineering examples and operating experience, the future scheduling programming operation implementation prospect is looked into the distance.

Abstract:In the testing of commutation station, the polarity and transformation ratio of CT need to be obtained by measuring the current magnitude and phase of the second side of CT. In this paper, calculation method of reactive power when transmitting different active power is inferred, of which the rightness is verified by testing data in the case of Zhengping commutation station. Calculation method of the second side of CT of converter transformer is proposed. Rightness of CT polarity and transformation ratio is confirmed by comparison with current value and calculated value of the second side of CT of testing data when transmitting 10% of nominal active power.

Abstract:Through the comparison of the testing methods of traditional relay protection devices, an automatic testing method is introduced. It is based on IEC 61850 communication standard and applied to the relay protection in intelligent substations. In this method, modular testing unit is designed targetedly with the standard logical node and data obejects in relay devices. The method is interoperable and information-sharing, satisfying relay protection devices produced by different factories. Further more, taking the charactristics of intelligent relay protection device into account, function testing unit can make use of sampled values (SV) and general object-oriented substation event (GOOSE) packets, so it is able to ensure the quality and speed of product development and engineering operation. The testing progress includes set of value parameters and function's investment or retirement, test project switching, saving test datas, test result analysis and assessment report formation. All these are automatic, so the automatic testing method can improve the efficiency of test work on deepth and breadth.

Abstract:In the view that the change of network management and control mode is carried forward on a national scale under the reform, the new problems exiting in abnormal failure analysis under centralized monitoring mode from the point of engineering reality are proposed. The new solution to fault diagnosis analysis of Power system based on the discrete event system theory. Some simulation works have been done on some real failure examples in Jiangsu Grid and have gained satisfied results.

Abstract:Bridge wiring and line-transformer unit wiring are widely used in 110 kV substation. Enlarged bridge wiring is less used because of its complex structure and secondary circuit of relay protection. Reconstruction projects of removing the third transformer are also rare in substations with enlarged external bridge wiring. Take the reconstruction project of 110kV Jiqing substation in Nanjing for example, this paper analyses the problems that should be taken into account when regulating the primary and secondary system. Announcements in acceptance tests and equipment operation are also discussed. The issues studied in this paper could help with acceptance tests and equipment operation, and offer solutions for similar problems.

Abstract:A power outage maintenance management decision analysis system is established in view of a series of problems for the current comprehensive power maintenance plan management. The power outage plan can be generated according to the project cycle and maintenance strategy, and then be merged and related with using topological analysis intelligently by the system which is based on the integrated power outage maintenance plan balance model. The purpose of integrated power outage maintenance plan multi-layer optimization and the establishment for power supply reliability rate and other reliability index calculation model is achieved by the system running well in Wuxi Power Supply Company.

Abstract:Building integrated monitoring system of auxiliary equipment in substation is the core for substation auxiliary equipment information centralized collection, intelligent abnormal operation analysis, centralized alarm released, and intelligent control linkage. In this paper, the design ideas that using the IEC 61850 standard to establish an integrated monitoring system of auxiliary equipment in substation are discussed, and the functions of the system based on the actual application needs are designed.

Abstract:Reactive power measurement principles of domestic and imported multi-function watt-hour meter are introduced. This paper proposes a method to refund reactive power in case of multi-function watt-hour meter fault with lacking phase which turns out that it works according to the internal structure of power meter. The quadrants of the multi-function watt-hour meter running in all kinds of power factor under phase-lacking failure reactive power measurement are given, which can be a reference for the field staff to deal with the energy metering fault.

Abstract:For the platen superheater of one 1 025 t/h CFB boiler, explosive leakage issues have occurred in the region near the front water wall for several times. In this paper, by using macro-examination, chemical element analysis, microstructure and microhardness analysis, the main reasons for these issues are identified. It can be concluded from the analysis results that, the overlay effects of the mechanical stresses in the region near the front water wall, the weak welded joints of the fixed blocks as well as the boiler's start up-shut down cycles will cause high-stress low-cycle fatigue fracture in the fillet weld of fixed blocks. The subsequent crack propogation finally leads to the explosive leakage issues.

Abstract:In order to solve the waste heat recovery issues of the high temperature exhaust flue gas in one 1 000 MW coal-fired thermal power plant, this work firstly introduces the design scheme for the low pressure economizer, and then qualitatively analyzes the basic design requirements. After that, through comparing the features of different design schemes, an optimal scheme is finally recommended. By employing the boiler design data, the economy of the recommended scheme is also analyzed. This work can provide valuable reference for other plants facing similar issues.

Abstract:Focusing on the serious hydrogen leakage issues occurred in one 660 MW coal-fired thermal power plant of Sheyanggang Power Generation Co. Ltd., field tests have been performed, and the obtained results have been analyzed so as to figure out the mean reasons. The detailed treatment measures for the detected leakage points as well as their effects are introduced. This paper also presents several feasible solution measures that can be adopted when facing serious hydrogen leakage issues.

Abstract:Electric vehicle wireless charging technology is a new energy supply mode for electric vehicle. The categories, operating principles and applications of wireless charging technology are introduced in this paper. The advantages and disadvantages are analyzed by comparing traditional energy supply mode and wireless charging mode, some suggestion for practical application of electric vehicle wireless charging technology is also proposed.