Abstract:Among renewable sources of energy, wind power is becoming the fastest growing form of electricity generation. It is of great importance for the planning and operation of wind farm to calculate the wind power penetration limit. This paper proposes an approach to calculate the wind power penetration limit based on DC probabilistic load flow computation. First, it analyzes the influence introduced by wind farm to the load flow of the power syste. After that, it builds a model to solve the wind power penetration limit by stochastic programming and genetic algorithm. Then results on IEEE30 system validate the proposed approach.

Abstract:The optimal sectionalizing number of transmission line with the consideration of reliability for various typical connection modes with different load density and substation capacity is studied. The optimization uses an economy and reliability combined objective function, and the construction and operation costs of substations and lines are considered. With the optimization, the optimal sectionalizing number of lines for a multi-phase load density and a universal substation scenario is obtained. The simulation results validate the proposed approach.

Abstract:The problems existed in current relay protection and fault information management station (PFIMS) are analyzed. Based the analysis, the principles for designing the new generation of PFIMS are presented. The architectures for software, hardware, database design, and application function of the new generation of PFIMS are designed, and the new generation of PFIMS is based on a uniform application platform. The panoramic models of the grid primary equipment, secondary equipment and its affiliated are realized based on IEC 61970, and the grid failure intelligent analysis is implemented. The designed system can be run independently and interactively with EMS on the uniform platform. Successful application of the designed system has been achieved in several power grids.

Abstract:This paper established a thermodynamic calculation program for steam turbines operating under different conditions. Besides, a thermodynamic model was also presented to calculate the change of heat consumption rate due to turbine efficiency deviation. Thermodynamic calculation for a 600 MW supercritical steam turbine manufactured by Shanghai Steam Turbine Company was conducted in detail. The results show that linear relationship exists between the variation of stage group efficiency, the heat consumption rate, and the turbine efficiency. In the same cylinder, the more power the stage group takes on, the larger influence it has on the heat consumption rate and turbine efficiency. LP turbine efficiency has the most significant influence on the unit heat consumption rate, HP turbine efficiency secondary, and IP turbine efficiency in the end. Based on the thermodynamic model, the change of heat consumption rate was calculated, and the results were in agreement with thermodynamic calculation program, which means that the present thermodynamic model is accurate enough for application. This work can serve as the foundation for analyzing unit heat consumption rate variation caused by performance deviation in turbine flow path.

Abstract:Reliable operation of DC system is very important for safe operation of substation. This paper uses an actual accident of the mal-operation of line protection caused by the rapid decline of DC voltage during the external fault to elaborate the analytical means of accidents. By analyzing the trip reports in DC system and fault records in line protection, it is confirmed that the expansion of fault area is caused by the internal fault of a single battery. Finally, several methods to improve supply reliability and avoid the similar accident are proposed.

Abstract:The accident of the successive tripping accident of Tongxi 767 and Yinwei 761 caused by in Chenxing Power Plant is analyzed. The tripping of Tongxi 767 which caused by some external force factors in 220 kV Tongwei substation of Lianyungangich finally results in the tripping of Yinwei 761. Through analyzing the causes of the accident, the protection configuration of the line and the principles of protection device, some problems existing in current 110 kV line protection configuration are discovered. With a deeply analysis of the action logic and order of protections, some measures for improving the protection are proposed.

Abstract:The efficiency of SF₆ leak detection is not satisfied currently. From the angles of detection accuracy, implementation methods, time-consuming of detection and detection results, this paper gives a brief review of the status of detection technology of electrical equipment SF₆ leak, and a comparative analysis of the advantages and disadvantages of various detection techniques is made. Based on the analysis, the detection principle and the advantages and disadvantages of infrared imaging technology for SF₆ leakage based on narrowband filter are described. With the application experience of the detection in recent years, the main points of infrared imaging detection and some detection methods are presented. Finally, the infrared imaging technology for SF₆ leakage is illustrated with a case analysis.

Abstract:A new method for harmonic measurement in power system is proposed, and the hardware schematic of implementing it is discussed. The proposed method is based on the multi-cycle synchronous sampling and simple algebraic operation in spectrum. The multi-cycle synchronous sampling technique guarantees that the synchronous sampling error with 10 cycles is under 0.03%. Then the harmonic components of the spectrum is obtained by simple algebraic operations, which enjoys the same accuracy as Hanning windowed DFT. The simulation results validate the proposed method, and the accuracy of the proposed method meets the national A-level standards.

Abstract:The mathematical models of micro gas turbines with different control modes and operation modes are introduced. Simulations for the micro gas turbines with different operation modes are implemented in PSCAD/EMTDC platform. The simulation results show that the dynamic response performance of micro gas turbines are satisfied for the cases of power reference value changing in grid-connected operation mode and load demand changing in island operation mode. The output power of the both cases can track demand changing quickly and the duration of transient process is short.

Abstract:Droop control is one of the commonly used control methods in microgrids. This paper analyzes the transfer characteristic of line power and reveals that in a low voltage microgrid with big resistance transfer lines, droop control of P-f and Q-V will lead to power coupling. Changing the controller parameters to make the equivalent output impedance of inverter inductive is not an absolutely effective method. Based on the idea of 'virtual impedance', a simulated virtual reactance with controllable value is added into the equivalent output impedance of inverter, which makes the transfer line inductive. The Q-V control curve is modified to ensure the steady-state accuracy of voltage control. The improved and conventional droop control methods are compared by simulations in PSCAD/EMTDC. The simulation results show that the reactive power allocation effort of improved droop control is better.

Abstract:With further promoting the implementation of smart distribution grid, distribution automation system is gradually covering the rural distribution grid. Since the distribution automation system is currently implemented only in urban areas, there are no implementation lessons available to draw upon for rural areas. Whether the communication scheme used in urban areas is suitable for rural areas is not clear. In this paper, we take Kunshan Huaqiao International Service Business Park distribution automation project as example to introduce how to select the communication scheme for the rural distribution automation system from the angles of channel demands, determination of communication methods, comparison of communication scheme and etc.

Abstract:The Voltage Adjusting Zone (VAZ) is critical to transformer voltage regulation. When the voltage level rises, the electric field environment of the VAZ becomes worse. Grading rings for improving the electric field distribution in VAZ are designed, and two methods to optimize the locations of grading ring are proposed. One optimization method is the normal step-by-step calculation method in which the grading parameters are optimized one by on and the other one is based on neural network model which is capable to obtain the global solution.

Abstract:As urban load density increase, the role of 35 kV grid gradually weakened. Meanwhile, new demands are raised for the selection of 220 kV substation low-side voltage level. A grid development cost model considering load density and 35 kV load proportion is proposed based on the minimum annual cost method. Simulation results verify that the proposed model is with a certain significance in guiding the selection of 220 kV substation low-side voltage level.

Abstract:With the popularity of smart grids, the distributed optical fiber temperature measurement technology has become a hot research area both at home and abroad. This paper introduces the research status of distributed optical fiber temperature measurement system, the basic principles and characteristics of Raman scattering measurement system, the structure of the cable temperature monitoring system based on fiber cable temperature measurement, and the application of distributed optical fiber temperature measurement system in the online monitoring of power cables. An actual example is taken to verify that the distributed optical fiber temperature measurement system is the most effective means to achieve fault diagnosis positioning in power cables online monitoring.

Abstract:The distance protection and directional protection in 220 kV substation require a lot on the secondary voltage size and direction of bus TV. Therefore, during the period of secondary voltage loop reform, constant voltage must be kept and the problems of loop ground and voltage polarity must be avoid. A 220 kV substation bus TV secondary loop reform is introduced in this paper. Based on the introduction, some problems should be noticed for future similar projects are discussed.

Abstract:In order to cope with the problems of large amplitude fluctuation and intensive frequency of active power brought by impact load, such as industrial mill and electric-arc furnace, high-voltage power regulator is used to maintenance frequency stability. The composition and control scheme of high-voltage power regulator and the control strategy for impact load balancing are introduced. Finally, simulations are implemented in PSCAD/EMTDC to validate the control strategy of high-voltage power regulator.

Abstract:The arrester current leakage tests for the case of DC reference voltage equals to U_1mA and 0.75U_1mA are routine projects. The 220 kV and above arresters are often comprised of multi-section units. Since arresters' manufacturing processes and other factors affecting the pressure ring, some differences are existed between each unit's voltage characteristics in the same phase arrester. When the differences are relatively large, DC leakage tests must be carried out on each unit of the arrester with removing connecting lead. Based on the analysis of the 220 kV and above arrester's voltage characteristics, a DC leakage test method of arresters based on the principle of voltage compensation is proposed. Also, a DC high voltage generator which is capable to adjust it's polarity is designed. The field tests validate the proposed test method.

Abstract:A detailed introduction is given to the Changzhou 500 kV grid line remote-tripping protection configuration wiring mode in this paper. Combing the introduction to the accidents of protection mal-operation, the remote-tripping protection configuration mode and operational logic of Local discriminating devices are analyzed. Based on the analysis, several improvement measures and suggestions are provided from the views of field operation and reliability.

Abstract:Distribution transformers are very important for the safe operation of power grid. Therefore, there is a need to evaluate the manufacturing capacity of transformers suppliers. In this paper, the analytic hierarchy process (AHP) is applied in evaluating the manufacturing capacity of distribution transformer suppliers. In the evaluation process, all key aspects related to manufacturing process of distribution transformer are taken into account. With the proposed evaluation system, the supplier can be regulated and the users can supervise the quality of products.

Abstract:In order to improve the accuracy of gas flow and pollutant concentration measurement, the computational fluid dynamics (CFD) software was used to simulate the flow field in clean gas flue for one 135 MW power plant. The distribution of the flow field characteristics in clean gas flue was analyzed with different gas flow. The results show that variation of the gas flow has no significant influence on the distribution of velocity in flue. The best uniform area appears in the middle of lower horizontal flue, and the appropriate position for flow measurement could be installed in this region.

Abstract:For the co-retrofit project of FGD booster fan and induced draft fan in coal-fired power plants, the axial-flow fans capable of adjusting the stationary and the dynamic blades are respectively analyzed and compared in this work from the aspects of device, initial investment, operation, and energy-saving. The results show that the fan capable of adjusting the dynamic blades should be adopted. The retrofit examples in one power plant demonstrate that the use of axial-flow fan capable of adjusting the dynamic blades can not only reduce the cost, but also achieve safe and stable operation. Besides, energy-saving effect is also significant.

Abstract:A brief introduction is given to the existing problems of the regular scheduled maintenance of electrical equipment in Coal-fired power plant. The necessities of electrical equipment status detection and maintenance for Coal-fired power enterprises are illustrated. Based on these introductions, the basic rules, methods and requirements of condition-based maintenance for electrical equipment in Coal-fired power plant are presented, and some issues related to the implementation of condition-based maintenance are discussed.