Abstract:The safe and reliable operation of high-voltage circuit breaker is of great significance. In this paper, the survey of mechanical fault types and fault reasons of high-voltage circuit breaker is introduced. Then the mechanical fault diagnosis methods of high-voltage circuit breaker are discussed. Furthermore, the deep analyses are carried out on the mechanical fault characteristic quantity extraction and mechanical fault identification method. According to the development of high-voltage circuit breaker mechanical fault diagnosis methods, the key problems and development tendency are pointed out.

Abstract:When the AC system connected with the sending end of HVDC power transmission system is a weak system, the modulation function of HVDC plays an important role. The HVDC system is an important means of modulation for stability control system. In the case of large power loss in the sending end, the stability control system needs to reduce the power HVDC delivered. Because of the minimum operating power limit of the HVDC system, when the power needed to reduce is greater than the maximum power which can be reduced, even if the power HVDC delivered runback to minimum operating power, it is still not enough and can lead to cutting off load in the sending system. In order to avoid cutting off load in the sending end, the modulation strategy for the condition that HVDC bipolar runback is not enough is proposed. The interface mode and information exchange between HVDC and stability control system are designed, and the HVDC control system program is developed. The proposed strategy and developed interface have been verified in RTDS. The simulation results show that the strategy is practical and effective. This research provides a reference for future similar projects.

Abstract:In order to cope with the impact of large power from outside on the power grid scheduling and safe and stable operation, the current situation of power from outside for Jiangsu Power Grid has been analyzed. Based on the analysis, from the aspects of power balance, increase of power from outside and low utilization hours of power generation, the main problems facing the coordination between inside and outside generation sources have been studied. The power regulating obligation sharing mechanism and the ancillary services compensation mechanism have been proposed for coordinating the operation of generation sources.

Abstract:The distribution grids in China are commonly in the way of closed-loop design and opened-loop operation. The distribution grids in cities has formed a "hand-in-hand" structure. Through opened/closed loop operation, power supply reliability has been improved. However, customers are still likely to suffer short-time outages. Currently, improving power supply reliability becomes an urgent demand. This paper proposes a solution for grid structure optimization based on the analysis of closed-loop operation mood of 10 kV feeder.

Abstract:With the technical features of smart substation and the requirements of its operation and maintenance, the paper proposes a design scheme for a multi-functional portable integrated tester, and introduces its hardware design, interface design, function design. The tester is suitable for a variety of test applications in smart substation, for example, secondary equipment test, time synchronization device test, substation network test, etc. It has a certain reference value to enhances the convenience and improve the efficiency of operation and maintenance of smart substation.

Abstract:In order to investigate the relationship between pre-compression and transformer winding looseness, the influence of different pre-compressions on transformer windings is analyzed using finite element method. The model of transformer is built in ANSYS Workbench so that modal analysis and harmonic response analysis can be carried out. The analysis results show that natural frequency decreases with pre-compression reduces. With excitation force, pre-compression change has great effects on vibration signal, and changing tendency is decided by structure. Therefore, through comparing the vibration response characteristics of transformer under different pre-compression to historical data, winding looseness can be identified.

Abstract:In substation, switchgear accidents and unwanted refuse operations of the protection devices for unknown reasons often occur. It can be found that the accident causes are often associated with DC power source. However, the real-time detection data of DC power source operation can't be provided. This brings a lot of uncertainties to accident analysis. In this paper, a comprehensive study on the fault and abnormal condition of the DC power supply system in substation is carried out, and a new method for rapidly starting wave-recording when failure occurs in substation DC power system is proposed, which provides a powerful support to fault analysis of DC power source system in substations and power stations

Abstract:Through analysis on the requirements of safe operation, a typical substation operation safety management system structure is proposed based on the computerized visual location and pattern recognition technology. After introducing the study of high-precision cross-camera location, the high-precision cross-camera location associated content including technical route, prerequisite, comparation with other methods, etc. are presented. In the end, the complete working procedure is explained by taking 220 kV substation operation safety management system as example.

Abstract:Transformer factories only design differential protection current software phase compensation for three kinds of transformer wiring groups, namely YNd11, YNd1 and YNy12, and their combinations, Currently, There isn't differential protection current software phase compensation for other transformer wiring groups and combinations. Through analyzing the changing law between the d side current phase of YNd3, YNd7, YNd5, YNd9, YNd11 and YNd1 transformers, this paper proposes to change the transformer protection's external current circuit wiring to transfer the differential protection current phase compensation of YNd3, YNd7, YNd5, YNd9 wiring transformers to YNd11 or YNd1 wiring transformers. Then through reusing the existing transformer differential protection current software phase compensation, YNd3 , YNd7, YNd5, YNd9 and other wiring transformers differential protection current phase compensation can be achieved. Reality application shows that the scheme is correct.

Abstract:The AC and DC ultra-high voltage grid develops rapidly in Jiangsu. Given that bulk electric power would feed into Jiangsu and the electrical distances between the AC and DC ultra-high voltage stations are very close, the impacts of the AC and DC ultra-high voltage may affect the safety and stability of Jiangsu grid significantly. To investigate the impacts of the ultra-high voltage alternating current (UHVAC) and ultra-high voltage direct current (UHVDC) constructions on the safety and stability of Jiangsu power grid, basing on the planning grid, the interactions under UHVAC and UHVDC faults are studied using BPA software in this paper. Meanwhile, the suggestions to improve the safety and stability of Jiangsu power grid are proposed.

Abstract:The synchronized phasor measurement based the Wide Area Measurement System is expanding and improving constantly, which provides important data to support power system observing. With the development of the Smart Grid, many new ideas about the synchronized phaosr measurement and application are proposed for reality applications. But those ideas are not systematized due to there isn't a unified principle to follow. This paper proposes a principle of time-space coordination based on the physical conditions and protocol support from the aspect of observability and controllability, and then introduces the application of wide area synchronized measurement in the protection and control of Smart Grid.

Abstract:This paper analyzes the characteristics of grid connection for wind power integration. For the reactive power voltage problem caused by wind power, a framework of voltage control for multi-controlled domain and multi-reactive power source coordinated wind power cluster is proposed. Under the normal and emergency states, the master station implements continuous and discrete reactive sources control for power plants, directed control substation, and wind power plant to optimize the allocation of reactive power in the system level. Wind power plant station implements SVC/SVG based fast response reactive power control strategy. Combined with the response characteristic of various reactive power sources, fast response delaying coordination control is implemented to reduce the effects of volatility and intermittent of wind power. Application in an actual system show that the control system can effectively restrain the voltage fluctuation and reduce the risk of wind power cluster disconnecting to the main grid.

Abstract:Computational theory of axial compression bearing capacity in different national and foreign design standards are compared. The axial compression tests of Q420 high strength steel tube with different slenderness ratios are carried out. Integral instability happens during the tests, and obvious local buckle appears in the section of 1/2 length at the end of test. The bearing capacities of Q420 high strength steel tubes are calculated and compared. The calculation results agree with the testing results of the steel tubes that slenderness ratio is smaller than 60, and the test results for other slenderness ratios are lager than the calculation results. The calculation results are conservative, which are obtained according to the code for steel structure design, AIJ 1990 of Japan, S37-94 of Canada and BS EN 1993, and the computational theory could apply to the engineering design.

Abstract:RTU (Remote Terminal Unit) plays a very important role in the oversea automation market, and the user's function need is changing. According to the renovation of old station and building of new station in the overseas, for the needs of IO acquisition, communication access and advanced applications, a multifunction integrated RTU design is proposed in this paper. A method of object-oriented, decomposition and refinement of the function to each subsystem is used in RTU design. IO acquisition subsystem provides access to the basic function of the hard signal, communication subsystem provides more stable and large protocol libraries, and advanced application subsystem provides additional features to improve the economic operation of the power grid. The RTU terminal has been successfully applied in Singapore and the operation is reliable and stable. The proposed RTU can meet the needs of users.

Abstract:Electric power equipments suffer from aging, wearing, and weather conditions in operation, the failure rate has a cumulative effect over time. Considering the main factors affecting the reliability of various electric power equipments, the time-varying failure rate model based on the operating conditions is established. On this basis, the important A-level and C-level preventive maintenance modes which have different reliability improvements in each preventive maintenance levels are built based on the effective age, and the average unavailability formulas of kinds of power equipment is derived. Then, the analytical expressions for the system reliability and economy indices are established. Finally, According to the studies on RBTS, the validity of the algorithm is verified, and the sensitivity analysis of the generator system is carried out.

Abstract:Taking 3-span and 6-span 220 kV truss-column frames as example, four types of commonly used substation frames are proposed and designed in this paper, and related finite element analyses are performed to study their force mechanism. The horizontal beam types and beam-to-column connections of different frames are investigated and compared. The research results indicated that, when beam and column is fix-connected, the usage of latticed angled beam is higher than tubular beam; when latticed tubular beam is used, the member usage of fixed frame is higher than pin-ended frame. The frame with pinned beam-to-column joints is flexible. Lastly, the reasonable 220 kV truss-column structure type is recommended, with latticed tubular beam, angle braces, and pin-ended beam-to-column joints.

Abstract:With the rapid development of economy, our country has entered a rapid construction phase of UHV power transmission and transformation project. Due to the rapid growth of the supervision work, the centralized supervision is generally adopted in the UHV GIS equipment supervisor, on the one hand, to integrate excellent manufacturing resources in several companies; on the other hand, to improve the efficiency of supervision. Three UHV substation have been built in Jiangsu power grid in 2015, and Jiangsu electric power institute have undertook the UHV GIS equipment supervision service, with the centralized supervision. The centralized supervision is of great significance due to discharge equipment, lax controls in the parts into the factory, and spare parts management confusion, etc., and the suggestions for the centralized supervision service are proposed.

Abstract:According to the demand of low voltage busbar protection in substation, the function of the simple bus protection is realized by using the substation-area protection based on the information of the station. Through the analysis of the difficulties of the existing low voltage busbar protection, with the application of the smart substation technology, the design of the simple bus implementation scheme, the principle and the action process analysis are given. The implementation scheme has been applied in the new generation of smart substation, which proves the reliability and technical superiority.

Abstract:When the operating voltage applied to arrester continuously, the current flowing through the arrester is the continuous current. When the arrester internal is damp, the continuous current increases. When the arrester varistor aging, the resistive current of continuous current increases. Therefore, before the arrester put into operation, the continue arresters current must be measured. This paper studies the existing measurement methods for GIS arrester continuous current. According to shortcomings analysis, a new method for GIS arrester continuous current measurement is proposed.

Abstract:There is no clear technical standard for the connecting and fastening terminal blocks and wires of relay cabinets in substation. To satisfy the construction demand of Nanjing UPFC project, experimental study on terminals and matched wires group in the relay protection control cabinet are carried through comparative analysis on loop resistance, pull off force, damage morphology of wires and fastening bolt in different fastening torque condition. The following conclusions are obtained through the study. The terminal of the relay protection cabinet must be installed with a torque screwdriver, and the cutter head size of torque screwdriver must be consistent with the size of the bolt slot. The connection fastening torque should be set to 0.5N·m for the general terminal block, and 0.7 N·m for the current voltage terminal block in relay protection cabinets.

Abstract:This paper introduces a hidden 35 kV MOV defect detected by infrared detector. It is found that the MOV leakage current measurement under continuous operating voltage is large. After replacing its visual inspection, the insulation resistance testing and leakage current measurement to the voltage U_1mA and 0.75U_1mA under 1mA DC reveals that the leakage current is abnormal. The MOV disintegration shows that the MOV is damp. According to the detection, it is recommend to strengthen the process control of MOV and deploy infrared temperature measurement when humidity is high.

Abstract:Analysis and processing of turn-to-turn short fault of a 390H generator rotor is presented in this paper. The vibration inspection and electrical tests are carried out. According to the results of the inspection and test, the conclusion of rotor turn-to-turn short fault is conducted. Through the disintegration analysis, the fault reason is obtained as deviation of turn-to-turn insulation of rotor. The corresponding treatment of turn-to-turn short fault of generator rotor is also introduced.

Abstract:Filter is one of the most important reactive compensation and harmonic filtering equipment in power system. So it is very important to accumulate experience of its operation, accident analysis and maintenance. Based on the actual transient fault record waveforms of protection devices, the analysis and calculation for an atypical power filter capacitor accident is given in the paper. The simulation model for verification is built in the electromagnetic simulation tool of PSCAD/EMTDC using the actual system primary equipment parameters. The analysis and studies for this accident case are verified by the corresponding transient simulation and calculation. The simulation curves and data are almost the same with those in the actual transient fault recorded by the protection devices. Hence, the effectiveness and correctness of the analysis progress are verified and confirmed. Finally, some constructive suggestions on rectification and maintenance for this accident case are given.

Abstract:The electro-deionization (EDI) system is responsible for the water preparation process' final procedure. Failure of EDI may not only affect the water quality and production capability, but also lead to undesired outage of the associated water production equipment; consequently, the whole plant may even have to be shut down. In this paper, we firstly analyzed the problems encountered by the EDI operating in one power plant thoroughly; then, solution measures were proposed. This work can provide valuable reference for similar EDI systems in other power plants.

Abstract:Focusing on the issues encountered by the dynamic separators in Yizheng Chemical Fibre Production Centre, we proposed several measures to optimize the structure and parameters of the original separators. After performing these measures, the separators' performance was analyzed by using field testing data. The results indicated that both the separation efficiency and the uniformity of the pulverized coal had been significantly improved; also, the output capacity of the separators had been increased.

Abstract:The case of retrofitting the boiler reheater heating surface in one 320 MW power unit was introduced in this paper. Through seriously comparing various potential retrofit schemes and carefully analyzing the boiler's design characteristics, one most appropriate scheme was finally determined. After reducing the reheater heating surface, the reheated steam temperature was decreased, and the amount of attemperating water was also reduced. The operating data obtained before and after retrofit were compared, and the economic benefits achieved through performing retrofit were also analyzed. This work can provide reference for similar power units.