Abstract:As controllers of flexible AC transmission system (FACTS) in power system is designed independently, studies have shown that there exists negative cross-impact among these controllers. The effect of FACTS controllers is weaken due to negative cross-impact. A kind of multi FACTS coordinated controller is designed based on sliding mode control. The coordination of multi FACTS is achieved, and the control of multi FACTS is improved. Finally the time-domain simulation of a single-machine infinite-bus system with static var compensator (SVC) and thyristor controlled series capacitor (TCSC) is performed to verify the effectiveness of the proposed method.

Abstract:With the rapid development of power grids, the management and dispatch for power systems are deeply done in a hierarchical and distributed manner. Total supply capability (TSC) of zone grids becomes a very important problem which has attracted many attention by power systems planning and operation departments. Optimal power flows based TSC calculation method is investigated in this paper. The TSC can be handled as a nonlinear programming problem, which satisfies certain physical and operating constraints. Critical interface flow limits are introduced in order to consider N-1/N-2 contingencies indirectly. The nonlinear interior point method is employed to calculate the TSC. Numerical results of Jiangsu power grid are presented. The proposed method is practical and effective.

Abstract:The low rate of using automation equipment, big amount of distribution network model data, incompletion of fundamental data and lacking of real-time measured information, a method for load verification and information completing based on electricity data collecting and load characteristic analysis is proposed. By using optimal multiplier method, combining radial distribution network structure and adopting block sparse matrix technology, the proposed method ensures the convergence, fast speed and accuracy of power flow calculation, which satisfies the engineering requirement and can be used in practical engineering projects.

Abstract:The paper presents an automatic IEC 61850 modeling scheme for intelligent device of PCS-9550 HVDC control and protection system. Firstly the scheme defines mapping regulations between structure of graphical program and hierarchical model of IED, and designs corresponding graphical modeling symbols, data templates and processing scripts. Then it links program variables to input notes of the graphical modeling symbols with connecting lines and sets descriptions and other properties of these symbols in graphical pages. Finally the scheme executes corresponding scripts of the symbols to create logic nodes dynamically and generates DOI contents of data instance during the code generation period. Therefore, the scheme generates IED model file automatically and improves engineering efficiency.

Abstract:Two-point grounding faults in different phases and lines can be frequently caused by single-phase grounding fault in small current grounding power systems. When two-point grounding fault occurs in different phases in arc suppression coil grounding system, due to the influence of neutral point current injection, a difference occurs between the two fault lines, which can cause protection refusing to trip. Based on the circuit superposition theorem, this paper derives the deviation calculation formula. By using fault current's waveform, the protection action is analyzed. Moreover, other kinds of grounding problems are analyzed when two-point grounding faults occur in different phases and lines, which provides references for future studies.

Abstract:As one important defects inspection technique, IR temperature measurement technology has the advantages of no contact, no sampling, no blackout, convenience, intuition and accuracy. The main problem found by IR temperature measurement technology is poor contact joints which is not paid enough attention to. In this paper, 2 case studies are provided with reason analysis and countermeasures for poor contact joints.

Abstract:Analysis on the typical faults encountered in the leakage control system of air preheaters was performed, and then detailed solution measures were proposed. Through performing technical reform to the leakage control system, serious faults affecting the normal operation of the control system were eliminated, and issues associated with the clearance measurement accuracy were also solved. The reliability and safety of the leakage control system were significantly improved, while the maintenance cost was reduced. The desired results were finally achieved.

Abstract:Analysis indicators of generators' leading phase based on operation data of generators are established in this paper. According to these indicators, this paper analyzes the situation of generators' leading phase during low loading level in Jiangsu power grid, and draws the conclusions that the voltage qualification rate can be increased by strengthening the management of generators' leading phase. At last, in order to strengthen the management of generators' leading phase fairly, penalty factor and reward factor are established according to the actual situation of Jiangsu power grid.

Abstract:Grid-connection projects of 10kV distributed photovoltaic power generation have been widely spread, and most of them are still out of the control of the power dispatch center. Currently, distributed photovoltaic system islanding protection measures are still based on user side's inverter, therefore new islanding protection measures on grid side are needed to be studied. Based on the reform of grid-connected switchgear, closing and locking link and GPRS remote monitoring control system, the reverse power supply of 10 kV distributed photovoltaic power generation at grid connection point is effectively prevented.

Abstract:An improved hybrid differential evolution algorithm is proposed to solve power system transmission network expansion planning optimization problem. During the evolution, dynamic parameters adjustment mechanism is adopted in the proposed approach. According to population aggregation, chaos searching strategy is used for the optimal individual to enhance the searching ability in the later evolution period. Despite for the simplicity of differential evolution, the proposed approach can improve the globally optimization. The simulation results on two test systems show that compared with genetic algorithm, particle swarm optimization and differential evolution algorithm, the proposed approach has better performance in solving transmission planning problem.

Abstract:For main protection and backup protection integrated 220 kV transformer, star connection must be adopted in each secondary side of the transformer. The method of software varying phase is widely used for current phase compensation, which can't be used directly for some transformer such as YNd5 wiring transformer. A method, that can transfer the phase of the secondary wiring with YNd5 wiring to the phase of the secondary wirering with YNd11 wiring, is proposed in this paper. Then current phase compensation can be applied to the transformer with YNd5 wiring. This method has been successfully adopted on a customer substation, and the loading test result shows that the current phase relation between high and low voltage is as expected.

Abstract:In recent years, low frequency noise produced by transformers has attracted many attention and became a hot research point in noise source control. In this paper, bubble sort is adopted to automatically identify the frequency components with most energy. Based on the identification and with the application of perturbation technique and merging algorithm, secondary sound source is automatically produced to neutralize the primary sound source made by transformers, in this way the noise from transformers can be eliminated. The noise data of an actual 110 kV substation is measured and analyzed theoretically. Simulation results show that the proposed method is effective and correct.

Abstract:The reactive power between the parallel operated generators must be reasonably allocated between the parallel operated generators. The natural adjustment by generators alone cannot meet the requirement. Appropriate reactive power allocation is for economic operation of generators and power systems' stable operation. In this paper, the effect of the reactive power compensation coefficient in excitation voltage regulation system, the principle of the reactive power compensation coefficient, the calculation of reactive power compensation coefficient and several testing methods are introduced. As one of the most important methods, reactive indirect adjustment method is highlighted.

Abstract:Based on the analysis on EMS system, an equipment abnormal signals processing system for power grid is developed by using ruler and case hybrid based signal correlation analysis and fault diagnosis method. This processing system is capable for signal correlation analysis and fault diagnosis. Application results on the actual power system show that the system can correctly analyze alarm signals and support dispatch personals making decisions.

Abstract:Ningxia power grid's dynamic real-time generation schedule is achieved considering generating units' operational modes, day-ahead generation, ultra-short term load forecasting, new energy forecasting, tie-line assessment and grid real-time topology. Taking SCED as the goal, the generation schedule function can be automatically updated and then the updated schedule signals will be sent to AGCs to ensure power systems' safe and stable operation. This function realizes automatic rolling adjustment closed-loop control of generators. The function paralleled with AGCs can coordinating generation schedule and power gird dispatch. This can improve the efficiency of generation schedule implementation and satisfy the evaluation requirement. The function ensures power grid's security and reduces workload of dispatching personnel, which improves the efficiency of processing accidents.

Abstract:The status of Nanjing power communication transmission network is presented in this paper. With the rapid development of power communication services, problems in Nanjing power communication networks in four aspects of network topology, hardware configurations, management method and integration of information & communication are analyzed. Accordingly, targeting to optimize Nanjing power communication network, suggestions and countermeasures are presented.

Abstract:Compared with the excitation system of conventional thermal power unit, there are something special in the design of excitation system used in gas turbine because of the requirement. This paper discusses the functional requirements and application solutions in the domestic excitation system which satisfies the special requirements in different operation stages. The useful reference to function improvement of domestic excitation system is expected based on the practical application on the imported gas generator.

Abstract:In this paper, a typical 500 kV double-line suspension angle tower is taken as the target for the analysis of magnetic field under transmission line. Three-dimensional refined model of tower is established in SolidWorks. The equal ratio modeling of insulation strings, grading ring and link plate are provided. Using finite element software the parameters of transmission lines are obtained. Through hybrid mesh generation the three dimension distribution of magnetic field around transmission lines is acquired. The magnetic field distribution analysis of transmission lines with 3 kinds of magnetic phase are provided, namely uniform phase order, inconsistent phase order and various phase order, are provided. The analysis results show that the magnetic field of transmission with uniform phase order has the maximum ground field strength while the inconsistent phase order has minimum ground field strength.

Abstract:Vibration anomalies occurred on No. 1 bearing bush of one 1000 MW power unit after the unit was put into operation. Preliminary analysis, carried out during operation periods and combined with the bearing bush inspection after the unit was shut down, confirmed that the defects of bearing installation, the lack of bearing stability and the static and dynamic components rubbing of the high-pressure rotor were the main reasons for the bush vibration anomalies. Through analyzing the problems, corresponding solution measures were proposed. After implementing these measures, the bush vibration anomalies on No. 1 bearing bush were finally solved.

Abstract:The refrigerating system of the main machine hall employs the modular air-cooled chiller unit to provide chilled water for the air conditioning system and the cooling-ventilation system. The designed outlet water temperature is 7 ℃, while the backwater is expected to be 12 ℃. However, in practical operation, to meet the actual condition that the refrigerating system is always operating under partial load condition, the outlet water temperature is intentionally improved by 3 ℃. This significantly benefits the energy efficiency ratio of the refrigerating system, and can achieve desired effect of energy-saving and cost-reducing.

Abstract:The reheat-steam temperature of one 330 MW coal-fired power unit in Jiangsu had been lower than the design value for a long term. It not only affected the economy of the power unit, but also caused serious erosion to the last stage blades of the steam turbine. Through increasing the area of the low-temperature reheater in vertical position, the reheat steam temperature can achieve or even exceed the design level, which could bring huge economic benefits for the power unit. Moreover, the wear and tear problems associated with low-temperature reheater were also solved, which could significantly improve the safety and economy of the power unit.

Abstract:The advantages and disadvantages of the currently available solution measures, proposed for solving the low-frequency vibration issues encountered after performing frequency conservation retrofit to the condensate pump, are introduced. The key factors inducing low-frequency vibration are analyzed, and the most effective solution strategy is established.

Abstract:The necessity for performing desulphurization retrofit in #8 unit of Jianbi Power Generation Company is introduced, and the basic principle of the adopted two tower-two cycle technique is presented. Through analyzing the field testing data, it is confirmed that this technique can achieve higher desulphurization efficiency and significantly reduce the emission concentration of SO₂ at the outlet of desulphurization system. This work can provide valuable reference for the retrofit of similar desulphurization systems.

Abstract:A new kind of relay protection digital simulation system based on platform technology is proposed in this paper. The proposed system is capable for full function simulation of various types of relay protection devices. Through function abstraction of various types of relay protection devices, decomposition of the hardware configuration, software attributes and protection logic are achieved. Based on the decomposition, a protection device development platform is established. The developed platform can simulate various types of protection devices and plays an important role in many aspects of relay protection device development, testing and analysis.