Abstract:When voltage tends to instability, SVC (Static Var Compensator) may fail to prevent it due to the slow reactive power output speed. For this situation, an fast control method of SVC to prevent voltage instability is proposed. The out-of-limit of VIP(voltage instability predictor) is set as the starting condition of this method. The reactive power output speed of SVC is raised by adjusting the voltage reference of SVC controller, thus voltage instability is prevented. PSCAD/EMTDC and MATLAB joint simulation is adopted for example analysis, and the results prove that the control method improves voltage stability. Moreover, the method only adjusts external data of SVC control system, and the original structure and parameters of SVC control system are not changed, so it is easy to apply the method current actual power system.

Abstract:This paper proposes a Power Consumption System with the considerations of photovoltaic power and regular power. A mathematical model for photovoltaic power consumption analysis is built and the way to solve the model is provided. The IEEE 26-generator 24-bus test system is taken as an example and three scenarios of it are analysed with the method of GAMS. The results show that the generation cost is reduced and reactive power consumption is increased with the integration of photovoltaic power. It also reveals that there exists tight connections among generation cost, generation output and power system stability, which validates the effectiveness and correctness of the proposed system.

Abstract:Monthly electricity demand forecasting is the main content of medium-term load forecasting and the base of monthly scheduling for the power grid operation. This paper proposes a wavelet based monthly electricity demand forecasting method. It consists of three steps: first, the wavelet transform converts the original data series into several coefficients which are down sampled; second, inserting zeroes between each coefficient to recover the coefficients to the origin length; finally, RBF neural network is adopted to forecast the coefficients. By decomposing the monthly electricity consumption data series into trend component and fluctuation component and forecasting each component separately, the proposed method greatly improves the precision of monthly electricity demand forecasting.

Abstract:This paper studies a failure caused by a 20 kV vacuum-breaker' shunt connected reactor over-voltage in a 220 kV substation. Based on circuit theories, the mechanism of over-voltage in the process of vacuum-breaker switching on/off its shunt connected reactor is interpreted. Through building the electromagnetic transient model of a 20 kV power system in PSCAD environment, the over-voltages at bus side and reactor side with different shunt connected capacitors are calculated. It shows that a regular lightning arrester can only restrict the magnitude of over-voltage, and has no impact on its frequency and gradient; existing lightning arresters are ground-based, which is ineffective for restricting phase-to-phase over-voltage; and a reactor with shunt connected capacitor can both reduce the magnitude and gradient of over-voltage, which is effective to restrict the over-voltage in the process of vacuum-breaker switching on/off its shunt connected reactor.

Abstract:The mechanism and characteristics of steam-exited vibration fault were discussed in this paper. At a high load, larger half-frequency vibration occurred in NO. 1 and NO. 2 bearing of one 330 MW steam turbine. Based on the further analysis on the frequency spectrum of valve test and the mechanism of steam-exited vibration, it was deduced that the vibration was caused by steam-exited vibration. By adjusting the elevation of NO. 2 bearing, we solved the turbine vibration successfully.

Abstract:With the development of communication technology, the information of power network operation and fault and the data of primary equipment condition monitoring are merging to each other. The mergence makes it possible to achieve fault diagnosis with multiple data sources. A comprehensive data processing method based on lightning location information is proposed for fault diagnosis in this paper. The basic composition and data feature of the power network fault information system and lightning location system are analyzed. Based on the analysis, a fault analysis flow with lightning location information by utilizing stage fault analysis strategy corresponding data processing method is proposed, and a corresponding data processing method is provided. Finally, a practical fault of a 220 kV transmission line is taken to interpret the procedures and effectiveness of the proposed method.

Abstract:This paper proposes maintenance operation modes for replacing wires hanging straight tower V-strings and string tension tower tension insulator with the consideration of characteristics of equipment of ±800 kV UHV Jin-Su project. Also, for meeting the need of replacing insulators, some working apparatus, such as six-thread lift conductor, titanium fixtures for insulation and replacement boom-string are developed. The field application of the developed operation modes and working apparatus in ±800 kV UHV Jin-Su project shows that the maintenance operation modes and working apparatus are safe and easy to operate.

Abstract:Telephone and terminal message are two major tools used by electricity emergency center to control power load during the summer (winter) power peak period in the past. For improving the service of power marketing management and enhancing the communication with customers, an Orderly Power-Use Information Distribution System is developed based on several Java frameworks and MAS service based modern communication technologies. The system is capable to conveniently, flexibly, and efficiently delivery signal of orderly using of power to customers, which can help customers to adjust their power-use timely and to arrange power-use reasonably.

Abstract:Due to lack of the capacity of real-time updating power network's model information and operational mode, traditional off-line analysis software for power system grid closing loop operation risk analysis only can provide an approximate result. An Energy Management System (EMS) based regional power grid risk analysis software for closing loop operation analysis is presented. The proposed software is capable to provide a real-time grid closing loop operation risk evaluation. It collects real-time data of power network model and its operational mode from EMS, which makes it possible to achieve thermal stability analysis, N-1 analysis and circuit breaker interrupting capacity checking of electromagnetic loop network grid. The utilization of EMS in the proposed software reduces risk analysis computational complexity. The proposed system has been successfully applied into the Shenzhen power grid.

Abstract:Based on the analysis of two modes of setting group remote modification in the relay protection equipment, a new mode with prepared setting group section is proposed. The new mode can rapidly and reliably modify the setting value with setting group section unchanged, which reduces potential safety hazard and improves the efficiency of power supply.

Abstract:This paper analyses various operation conditions of magnetically controlled reactor in HVAC transmission system, and introduces the protection configuration of reactor. Especially, reactor differential protection with automatic tracing and compensating rated current, reactor inter-turn fault protection based on time domain translation balance differential protection, and voltage differential protection of control winding are proposed. The results of digital simulation test, dynamic simulation test and field operation validate the proposed protections.

Abstract:Energy storage technology is the principal tool to smooth power fluctuation produced by roof PV in regional micro-grid. In this paper, demand-side resource is takne as a tool to smooth power fluctuation in microgrid, so as to decrease the energy-storage capacity in a high PV penetration rate situation. The method includes two levels which are day-ahead plan and real-time control. The day-ahead plan includes prediction of intermittently photovoltaic power generation and presetting power curve of controllable load such as central air conditioners and other loads with slow rate of power change. It is for handling the change of photovoltaic power generation. The real-time control is to use the interruptible load to response to instant fluctuation of photovoltaic power. The measuring precision is the critical factor in the real-time control process. Through the day-ahead plan for controllable load and the real-time control on interruptible load, the power fluctuation caused by slow change or instant change of photovoltaic power generation could be effectively eliminated with taking the full advantages of demand response technology.

Abstract:In the environment of smart grid, for analyzing entire power systems' state, and the scheduling of a superior level needs a lot of data and information from the lower level, as well substations. Due to the existing data barriers between heterogeneous systems adopted by superior and lower levels, data sharing between them is very difficult. This paper proposes a method for remote data access in heterogeneous systems, as well as its implementation scheme. The proposed method solves the problem of data access between heterogeneous systems, reduces the pressure of superior dispatching, and benefits the system's monitor.

Abstract:In order to standardize the basic technology and data of energy-saving industry and to establish a unified energy efficiency data center, a provincial energy efficiency management platform is designed. It achieves the functions of filtering energy efficiency project, project design, contract signing, monitoring and display, statistical analysis, assess and evaluation, and so on. Based on WebLogic application server and DB2 database management studio, a platform is developed with the technologies of flex and AMF, and is applied in all thirteen cities of Jiangsu Province. The application shows that the platform effectively promotes the standardization, specialization and normalization of the energy efficiency management.

Abstract:According to current situation of use and management of switch in smart substation, measured objects of switches, data acquisition, and data procession are analyzed. Based on the analysis, an anti-blocking parallel data acquisition scheme which is compatible for multi-vendor and multi-type switches is designed. Also, a corresponding substation switch monitor program is developed. The proposed scheme and program makes on-line monitoring possible.

Abstract:This paper proposes a multi-municipal unified smart electricity acquisition system for Jiangsu power grid. The smart electricity acquisition system gathering electricity information from generation side, transmission side, and transformation side of Jiangsu power grid which includes all kinds of power plant and 3000 35 kV and above level substations. According to predefined calculation formula, the electricity of transmission lines, clear electricity of power plants, total electricity supplied to cities/counties, power losses and so on are calculated. The proposed acquisition system is taking a key role in electricity information collection and management in Jiangsu power grid.

Abstract:Static Var Compensation (SVC) device has been widely used in iron and steel enterprises. For enterprises' safe production, it is critical to keep SVC operated in a state. In this paper, the anti-jamming performance of two kinds of typical trigger device in the environment of electrical equipment discharge is analyzed, and the reason of causing SVC single-phase SCR breakdown is obtained. Based on the study, we suggest general industrial users to pay attention to the impact of electrical equipment discharge on trigger device.

Abstract:This paper proposes a new method to discriminate the faulty zone for cable-overhead mixed lines in regional power grid based on Flexible Optical Current Transducer (FOCT)and smart substation technology. The overall scheme of the new method, as well as the device realization, maintenance and error handling are discussed in details. The practical application of the method indicates that it is effective to discriminate the faulty zone in regional power grid.

Abstract:In order to reduce oscillation and hang-down-arc-curve of jumper conductor and to minimum the size of pole and tower, rigid jumper to conduct electric current are widely used for UH voltage transmission lines. Aluminum tub jumper is a kind of rigid jumper. Due to extra axial force on formal designed aluminum tube connector or improper constructions, aluminum tube connector slipping happens sometimes. To solve the problem, two improvement programmers are proposed in this paper. One is to tap and install the screws on inner connectors, and the other one is to weld ring flanges at the end of aluminum tube connector. The construction steps, related matters, test results, and results comparison of the two programmers are provided. The test result shows both of these two programmers can effectively prevent the skidding of aluminum tube connectors and guarantee the entire transmission lines' safety.

Abstract:The State Environment Protection Department has made clear requirement for removing the bypass flue in the desulfurization systems. The 2011 version of Emission Standard of Air Pollutants for Thermal Power plants has also imposed higher demand on the sulfur dioxide emissions. In the construction process of one 600 MW power unit, active measures were adopted to optimize the related systems and improve the reliability of generation units. This can ensure that no more large reform is needed in future. The investment cost is reduced, the adopted desulphurization system, however, can meet higher demand.

Abstract:Mental temperature anomalies occurred on NO. 1 bearing bush of one 660 MW unit during the start-up processes. Preliminary analysis, carried out during operation periods and combined with the bearing bush inspection after the unit was shut down, confirmed that the poor positioning performance of the bearing bush caused by impurity was the main reason for the high temperature. Through tracing the lubricating oil and the rust within the bearing pedestal, it was found that the location where the valve lever leakage steam of Unit 2 entered into the gland seal system was unreasonable. Defect elimination measures such as removing the foreign bodies, scraping the bush, and grafting the valve stem leakage pipeline were proposed. After implementing these measures, unit bearing temperature can be maintained at normal levels.

Abstract:Power plant circulating water systems adopting sea water cooling can be easily affected by the quality of water, especially the algae in the sea water. Algae not only influences the efficiency of condenser's heat transfer, but also can block or even break the associated gear of the circulating water systems. This paper introduces some methods aiming to solve the blocking of rotary filtering net affected by algae in some power plants, such as increasing protection logic, installing trash floats, adding secondary filter continuous flushing program, and actively contacting the local water conservancy departments and so on. With these measures, the effects of the algae were effectively suppressed, and the plant successfully completed the full load test.

Abstract:The operation and maintenance of UHV AC transmission line in China is reviewed in this paper. Based on the practical experience of China's first 1000 kV AC UHV transmission line, the operation characteristics of UHV transmission line are summarized. The research on and application of anti-accident measures and key technology for UHV transmission lines are also introduced. The data provided in this paper can be taken as a reference for further study of operation and maintenance technology, so as to guarantee UHV power grid's safety.