Abstract:With the rapid growth of power load and the centralized integration of large-scale new energy, high voltage, long-distance and high-capacity transmission will become the direction of the development of power grid in the future in China. In the background of the UHV power grid, combining with domestic and foreign advanced experiences of enhancing the transmission capacity of the power grid, especially the researches of new technologies, new materials and new methods applied in the power grid, this paper elaborates the main factors affecting the transmission capacity of the main grid comprehensively. On this basis, it gives some feasible methods to enhance the transmission capacity and their characteristics in this stage. According to their implementation methods, they can be divided into three categories, including changing the structure of the power grid, changing the electrical characteristics and installing grid security and stability control devices. Combining with the network characteristics of UHV power grid, this paper examines the applicability of various methods for UHV power grid, and proposes a suitable solution for UHV transmission network.

Abstract:This paper establishes the economic evaluation model of transmission means of the offshore wind power based on the full life cycle cost (LCC), with considering the initial investment costs, operating costs, maintenance costs, failure costs and disposal costs of the offshore wind power transmission system, to seek the optimal economic and persistent solution to ensure its safety and reliability in the whole life cycle. With comparing the high-voltage AC transmission, the traditional HVDC and flexible HVDC manner for the offshore wind power, according to their characteristics in a typical transmission project as an example, this paper analyzes their LCC situations for different transmission distances and capacities of the transmission systems, and gives a variety of LCC scopes in different transmission modes. Numerical example shows that this method can overcome the one-sidedness of the traditional assessment methods, and reach more scientific and comprehensive economic evaluation results, with perfect practical value.

Abstract:Malfunction of the protection devices caused a serious impact on the power system, especially its safe and stable operation. Crosstalk of the AC and DC power is the main factor that caused the malfunction of the protection devices. An unit outage caused by a mistakenly jump of the excitation switch in a power plant is described, as a result of the AC into DC control loop. Also the preventive measures are proposed from the design, construction, testing and other aspects.

Abstract:During a failure of the 10 kV line in a 110 kV substation, the main transformer protection will take action if a coincidence happens during the failure. With the fault waveform and the analysis of the current circuit diagram, the whole process of the failure is shown and ultimately the point of the failure is determined. This can provide experience for reference for the malfunction of the main transformer protection, on the condition of little resistance grounding.

Abstract:Parameters of the power transmission line are the base of power system load flow calculation as well as protection value setting. Acquiring accurate values of the parameters are important for power system operation arrangement and relay protection's reliability and sensitivity improvement. A method is proposed to calculate the sequence parameters of transmission lines based on the decomposition of the induced voltage (current) into positive, negative and zero sequence. The proposed method and traditional method are applied to calculate the sequence impedance of 4 transmission lines on a same tower. The comparison of these two results shows that the two methods have almost same accuracy which means the proposed is qualified for measuring. The effect of voltage amplitude dispersion on the measuring results is discussed. It is shown that a larger amplitude dispersion of voltage indicates a smaller measuring error of the zero sequence impedance.

Abstract:This paper outlines the basic structure and working principle of the IF furnace, and analyzes the characteristics of its harmonic current theoretically. Using PSIM simulation platform, the six-pulse current-and voltage-IF furnace simulation models were built, and the characteristics of its harmonic current were analyzed in the simulation. Three kinds of governance programs were described, and the active filter (APF) was selected to compensate the harmonic of the IF furnace. In the actual project, APF was used to curb the current harmonics of the 6-pulse IF furnace, which achieved some satisfactory results.

Abstract:A wind farm covers a vast area and the capacitive current of wind farms' assemble lines are relatively large. Therefore, the grounding modes of these assemble lines are critical to the safe operation of wind farms and the entire power grid. Three kinds of grounding modes, namely through harmonic elimination cabinet grounding, through extinction coil grounding and through resistance grounding, are analyzed. Based on the analysis a method for calculating the setting parameters of zero sequence protection system is presented which provides a valuable reference for future similar projects.

Abstract:This paper first briefly introduces the operational principals of short circuit generators. Then from the point of view of high-power laboratory, the attenuation characteristics of the short-circuit current of China-made 6 500 MV·A generator is studied and its MATLAB-based simulation mode is established. Based on the simulations of the attenuation characteristics of short-circuit current, the best choices of force excitation multiples to meet the requirements of relevant testing standards for three typical external impedance conditions are identified. The results of this paper provide a valuable reference for future operation of high-power laboratory.

Abstract:This paper introduces the integrated smart DTU which can also be used as a regional substation. This terminal can reduce the number of layers of power distribution system and is flexible for various interfaces. It utilizes three-layer bus structure and a special interrupting technology for float calculation. The adaptations of object-oriented method and smart protocol based data exchange technology in its software make it compatible to the smart power distribution system. The terminal has been successfully applied in some smart power distribution systems of China's power grid.

Abstract:Direct current capacitor, which would affect the voltage of DC side, is one of the key equipment of static var generator. The DC voltage's stability relates to the capacity of SVG to achieve ideal control target. When a SVG compensates a three-phase equilibrium load, DC capacitor only plays the role of supporting DC voltage. In this case, a small DC capacitor is proposer in theory. However when a SVG compensates a three-phase unbalanced load, the negative sequence current would be produced. In this case, the DC side voltage would fluctuate in a frequency which is two times of power gird's operational frequency. Apparently, the larger the negative sequence current is, the greater the fluctuation of DC side voltage would be. Therefore, if the DC capacitor is not large enough, the DC side voltage fluctuation will exceed the permissible range, which will lead to a poor control effect. This paper deduces theoretically the minimum DC capacitor for a negative sequence current compensation. A method to force the DC side voltage fluctuation in the permissible range to ensure the normal operation of SVG is proposed. Finally we verify the correctness of the DC capacitor selection method through the PSCAD/EMTDC simulation.

Abstract:In this paper, the secondary systems' double configuration technology used in 500 kV intelligent substation engineering is discussed. We analyzed the double devices' information flow of process level, bay level and substation level, particularly studied the technology of double supervising and control. Based on the analysis, a proper backstage monitoring scheme is proposed. By analyzing the information flow of redundant configuration, the entire information flow in IEC 61850 communication protocols based intelligent substation is elaborated.

Abstract:Parallel connected double-track-lines based auto-transformer(AT) is a common way to supply power to high-speed railway (HSR). The distribution of current and its relation with the current of fault site are formulized for different faults. A method to identify fault type and its direction base on the comparison of the virtual values at Traction Substation, AT Post and Subsection Post is proposed for various faults. The proposed method combines the principal of "AT neutral current ratios", which is effective to identify fault's type and direction accurately which is valuable for power supply restoration.

Abstract:This paper first introduces the operational principal of the backup power for pitch system. With considering the characteristics of low-temperature resistance and long service time, a super-capacitor based backup power for pitch system is designed and built. The testing results suggest that the proposed backup power is qualified for various operational conditions of pitch system. The proposed backup power can improve the poor low-temperature performance and prolong the service time of traditional lead-acid batteries. It will also reduce the maintenance cost and increase the profit of wind turbines.

Abstract:The inlet feeder protection is widely used to block automatic switchover in case of its mis-operation in the 110 kV substations with sectionalized single-bus configurations. However, the protection would act improperly to fail to block automatic switchover when a phase-to-phase fault occurs. To improve the cooperation of the protection and switchover, the method of changing protection's direction from line to bus is proposed. Also, the way of adding a bus differential protection to improve the cooperation is proposed.

Abstract:Converter transformer is composed of two paraelled two-winding transfomers. This kind of connecting mode makes its protection configuration and inrush characteristics much different from common transformer. The overlay of the inrushes of two independent transformers may result in a similar characteristic of internal faults. Based on the analysis of the casue and influence of such a phenomenon of a real conveter transformer, a effectvie criterion for the block of overall diffrential proteciton of converter transformer is proposed.

Abstract:With considering data exchange between feeders of a smart substation, a new fault line selection device is designed without assembling any other devices. The designed device collects fault information of feeders through GOOSE and synchronizes the fault information of various feeders by using residual voltage as the reference of time. The fault line in the isolated neutral system is located by stable state quantity algorithm while the fault line of arc suppression coil grounding system is located by stable state quantity and transient state quantity combination algorithm. The RTDS testing results show that the proposed device is effective to locate the fault lines in various operational conditions of smart substation.

Abstract:In the design of Type II collector, silicon steel transformer is usually used as the key components. However, the interference caused by the collector to impact power meters is commonly overlooked by designers. This article analyzes the influence of the Type II collector on power meters based on the structural principle of type II collector and the operational principle of the power meter. Based on these analyses, suggestions to improve type II collector and power meter, as well as their on-site installation for avoiding the interference caused by the collector to impact power meters are presented.

Abstract:With the development of substation unattended, traditional automatic fire alarm system lost its function and new modes of firefighting needs to be established. In this paper, fire monitoring management system of regional substation based on local area network is proposed. The entire framework of the system and the functions and characteristics of its each part are elaborated. Then operation and maintenance of this system are introduced. Since the system operates in Changzhou, several fires have been warned in time which promoted regional substation fire equipment management.

Abstract:This paper first gives a state of the art of the development of distributed temperature sensor system at home and abroad. Then an introduction of the principles of raman based temperature sensor system is given with emphasizing on its application in power cable operations. At last, a practical example is used to demonstrate that distributed temperature sensor system is an effective means for power lines on-line monitoring.

Abstract:Taking one 660MW coal-fired power plant as an example, this work briefly introduce the control system for primary frequency modulation and the technical specification adopted by Jiangsu power grid. Based on the primary frequency test results, the control logic and several issues needed special attention are analyzed. This work can provide valuable reference for other similar power plants.

Abstract:Focusing on the technical retrofit implemented on the induced draft fan system of the 1 025 t/h boiler of NO. 8 unit in Jianbi Power Generation Company, analysis on the field test results and operating data is performed. In this paper, through comprising two proposed technical schemes, it is finally determined that the scheme employing the induced draft fan to replace the booster fan is accepted. The obtained test data show that this proposal can meet the practical requirements. It is also found that, after performing this retrofit, the station service power consumption rate is reduced by 0.2%.

Abstract:Retrofit for heat supply is now widely accepted in large-scale power plants. In this paper, the characteristics of heat supply load and three types of prediction methods are introduced in detail. A prediction technology for extremely short term heat supply is presented with practical engineering cases. Comparison between the currently proposed method with the traditional methods is performed. This paper also briefly introduces the application of this prediction technology in power grid dispatching management. It is believed that this technology can provide powerful support for the prediction of adjustable output of the whole grid.

Abstract:The low cooling performance of the hydrogen dryer and the substandard temperature of the outlet hydrogen are analyzed in this work. The structure and operating principle of the hydrogen dryer are firstly introduced, and then through deeply analyzing the operating condition and the fault, some detailed optimization measures are proposed. The proposed measures are proved to be reasonable and effective by the experimental data.

Abstract:In this paper, formation mechanism of surge phenomena occurred in air compressors is briefly introduced. The related reasons are analyzed, and the solution methods as well as preventive measures are subsequently proposed. Through analyzing the surge phenomena encountered by one instrument air compressor, this work also propose several optimization suggestions for the operation of instrument air compressors.

Abstract:Characteristics and main content of the Energy Performance Contracting (EMC) are introduced in this paper. By employing the closed water pump retrofit project performed in one power plant as an example, this paper also presents the detailed implementation scheme. The results show that the cost and risk of this scheme are low, while the efficiency is high. This work can provide valuable reference for other similar equipment.