Abstract:Output power disturbance of steam turbine could lead to low frequency oscillation of resonance mechanism, threatening the safe and steady operation of the power system. This paper compares the influences of the disturbance of mechanical part of steam turbine with disturbance of governor. The fundamental principles of resonance mechanism are presented in this paper firstly. Then, it will be proved that steam turbine has strong restrain effect on disturbance of governor through mathematical derivation. Influences of disturbance of mechanical part of steam turbine and disturbance of governor on low frequency oscillation are simulated in a single-machine and infinite bus system separately. The simulation results illustrate that disturbance of mechanical part of steam turbine leads to larger amplitude than disturbance of governor when the disturbances are of same amplitude and frequency. The simulation results are in accordance with theoretical analysis, which can provide reference for suppressing low frequency oscillation of resonance mechanism.

Abstract:This paper presents a method to design the architecture of cloud computing based search engine for the large-scale power network's unified multi-level scheduling management. With the integration of IT infrastructure resources of the large-scale power network's unified multi-level scheduling management sysytem, the data resources from various dispatching centers are effectively organized, dispatched and managed. This makes it possible to provide services of data sharing, interaction and retrieval for power network scheduling and management. Also, it is possible to custom data visiting and to visualize the data. The analysis of integrated cloud search engine architecture for the multi-level scheduling management is particularly stressed to provide a theoretical basis for overall design of search engine prototype system.

Abstract:The reasons of some typical transformer differential protection malfunction, such as excitation inrush current of transformer no-load closing, sympathetic inrush of energized transformer, restorative inrush caused by external fault cleared, TA transient saturation, partial transient saturation, and assistant of zero-sequence circulation current are theoretically and practically reviewed in this paper. Based on the analysis, some strategies are proposed to avoid these malfunctions. Understanding these problems correctly is helpful in developing, designing, debugging and operating protection device, which will improve the accuracy of transformer protection during field operation.

Abstract:This paper analyzes the process of zero-sequence direction relay mal-operation of a double parallel 500 kV and 220kV lines after a fault occurred at the end of the 500 kV line. The mechanism is studied, which shows that the mal-operation is caused by the zero-sequence mutual inductance between multi-transmission lines. In the case of grounding fault occurred at one of parallel line, the existence of zero-sequence mutual inductance would activate the zero-sequence direction relay of the other line. The conclusion of this paper will provide a valuable reference for similar faults analysis.

Abstract:A short-circuit failure of the main transformer caused by overheat of its low voltage switch contact in a wind power plant's 220 kV substation is studied. The reason of the fault, the action of relative 35 kV differential busbar protection, the main transformer protection and the wind turbines protection are analyzed. Based on the analysis of the operation rejection of main transformer's low voltage level back-up protection, countermeasures and suggestions for preventing fault, deploying protections configuration and reducing fault effect are presented to avoid similar accidents.

Abstract:The rapid development of the Internet Of Things(IOT) technology provides basis for auxiliary system optimization and smart substation information fusion. By taking the 220 kV XiLing smart substation an example, the acquisition and transmission system, one of IOT technologies, is introduced in this paper. Based on the analysis, an optimal arranging scheme of sensors using modified SOM algorithm is proposed. Since the data standard of auxiliary systems is not unified, a unified modeling method based on IEC 61850 standard is studied, and an IOT based auxiliary systems' management and control platform architecture scheme is proposed.

Abstract:Traditional automatic switching device lacks of flexibility in load-shedding. Adaptive automatic switching device is proposed to against the defect of traditional device. This paper introduces the principle of adaptive automatic switching device. Information interaction between the device and the substation integration automation system is discussed. The control processes of station equipment in the cases of normal state and fault state are studied. The proposed device intelligently shed less-important load according to real-time load situation. This approach can avoid fault expand brought by transformer overload after automatic switching device activated. It helps to improve power supply reliability and economy.

Abstract:A criterion for transient voltage stability of the power system with induction motor is proposed. The criterion determines the stability of the induction motor by analyzing slip change and comparing the values of electromagnetic torque and mechanical torque. Whether transient voltage instability of power system would be introduced by load instability is determined by the relationship between power systems' maximum power transmission capacity and load's power demand. The correctness of the proposed criterion is verified by the simulation results of a single-generator-single-load system and the IEEE39-bus system.

Abstract:To collet data automatically and improve the data acquisition success rate, the reasons of data acquisition failure are analyzed from the view of malfunction object, phenomenon and cause. According to statistical analysis and sampling inspection, it is concluded that the factors affecting data acquisition success rate mainly concentrate between the main station and the terminal and the terminal and energy meter. This paper analyzes several kinds of problems occurring between the main station and the terminal and the terminal and energy meter. Based on these analyses, a new method is proposed to improve the data acquisition success rate.

Abstract:The development of power system has a growing demand on stability devices. Stability control device producers face the problems of designing stability control device test system effectively, improving testing efficient, and guaranteeing devices' reliability. The demands of stability control device in term of functions and the problems urgent to be solved are analyzed in this paper. Based on these analyses, a LabVIEW based design of stability control devices test system is proposed. The proposed design is effective to promote the efficient of designing the test system.

Abstract:The operational principle of STATCOM is introduced firstly. Combining theoretical analysis with MATLAB software simulation, the operational state of the Taizhou 220 kV power grid is analyzed. Based on the analysis, the access point and the capacity of STATCOM to be integrated into Taizhou power grid are recommended. Using the recommended design, simulations of the Taizhou power grid with STATCOM have been implemented. Simulation results show that STATCOM can improve 220 kV power flow distribution and support the voltage of 220 kV.

Abstract:An on-line monitoring system is of great importance to ensure the safety operation of power transmission lines. A layered wireless sensor network (WSN) is designed based on arrangement and monitoring parameters of transmission line. ZigBee based sub-network aims to collect data from sensors and IEEE 802.11 based backbone network is designed for transmitting data with a long distance reliably. Wireless sensor nodes and monitoring substation of on-line monitoring system are designed, and corresponding hardware and hardware of them are introduced. A wireless link quality experiment is implemented, which shows that constant logarithmic distance decay model is highly consisted with the measured data, and RSSI could be taken as an indicator of the radio link quality.

Abstract:At present, the design of wind-solar hybrid power supply systems is based on personal experiences which could cause a deficient or excess in installed generation capacity. The design of standalone wind-solar hybrid power supply systems could be taken as a multi-objective optimization problem whose two objectives are maximizing systems' reliability and minimizing cost. The power supply reliability is guaranteed by checking a single year's battery's SOC which is mimicked by computer software, and the minimal cost for designing a wind-solar hybrid power supply system is searched by a dynamic GA. Combing with the concrete construction of Yangzhou smart grid state detection, the successful application of wind-solar hybrid power supply systems technology is introduced in detail.

Abstract:The state of insulator is critical to secure operation of transmission and distribution lines. The leakage current is a reflection of the surface state and discharge character of insulator because it exists all the time. Under laboratory environment, the rime is mimicked by human. Silicone rubber insulators are placed into the mimicked rime with various times to damage their insulation in different extent, and then voltage is applied to them to trigger flashover. Through using high speed video camera to record the phenomenon and process of flashover, the nonlinear character of leakage current can be studied by regression analysis which provides recurrence plot and quantitative index to characterize leakage current's internal variation. The result shows that the nonlinear character of leakage current is consistent with insulator's surface discharge phenomenon. The research reveals occurrence mechanism and developing process of insulator's flashover under rime environment, which helps to ensure the reliability of outdoor insulators.

Abstract:With the continuing evolve of smart substation technology, as well as the increasing complexity of construction scheme, the long-term operating performance of smart substation has proposed requirements to construction mode. This paper introduces new technical application of secondary system in the 500 kV TIAN-Muhu substation based on the State Grid's existing typical building program. On the premise to meet operational reliability, it proposes to promote a further combination of secondary equipment and to increase information fusion level of smart substation, which will achieve the secondary device function optimization.

Abstract:At present, water tree based evaluation methods used for medium voltage power cable condition monitoring and testing are inexperienced and lack of accumulated data. Therefore, the analyses, such as destructive testing, non-destructive detection, on-line monitoring, and non-electricity analysis derived from are naturally with disadvantages. For coupling with these disadvantages, a new technology of condition monitoring and testing is proposed with the utilizations of infrared diagnosis, online partial discharge, damped oscillation wave status online detection, ultra-low frequency dielectric loss test and new sensing monitoring technology. The proposed technology can be used for real-time monitoring and analysis of partial discharge of medium voltage cable and accessory equipment, which can obtain a more reliable result.

Abstract:The concepts of power demand side management and demand response are introduced, and then the development of power load management system is reviewed. Combining with smart grid construction, from the perspective of demand response, the direction of power load management development is presented. The direction is that the main power load management center should be able to grasp users' response capability data and load control terminal should be able to precisely control its consumption. The power load management system is a basis of the implementation of demand response.

Abstract:Utilizing the current and differential current waveform characteristic of transformer, a method for analyzing a 220kV transformer fault caused by an external zone fault is proposed in this paper. Based on the transient fault recorder data of transformer differential protection, theory analysis and calculation is implemented. The fault location and type is identified gradually by utilizing the reasoning and exclusion method. It is indicated that the transformer fault is balancing wing short circuit due to insulation damage. It shows that the transformer differential protection tripped correctly in this fault. More, the progress of this fault investigation and location is introduced, which is benefit to primary equipment inspection and deal with fault condition.

Abstract:The accuracy of electric energy metering device and correctness of secondary line connection are related with the economic benefits of electric power plant, electric grid corporation and consumers. Line connection detection is an effective method to ensure metering accuracy and line connection correctness. However, many problems, such as difficulty of selecting measure point, low automation degree, strong dependence to operator's subjective judgment, and possible mistake in restoring lines may face with line connecting detection. To solve these problems, a new method and design scheme of field electric energy metering device line connection detection is proposed in this paper. A sample machine is developed using the proposed design. Experiment has been implemented, which approves that the new apparatus can satisfy the need of field work.

Abstract:Through the tests of corrosion weight loss, corrosion potential and corrosion rate under laboratory environment, the corrosion characters and laws of three kinds of substation grounding material (Galvanized carbon steel, Copper and Conductive anti-corrosion coatings) in coastal saline soils (undisturbed soil and back-filing soil) are studied in this paper. The result indicates that the Zinc coating is with a high corrosion speed and cannot protect steel in saline soils. Also the conductive anti-corrosion coating is without significant protective effect. But the corrosion rate of Copper in the backfill is only about 1% of galvanized steel.The research results provide a specific basis to choose substation grounding materials.

Abstract:Through monitoring the temperature of various high temperature heating surfaces with thermocouples and IMP data acquisition systems, experimental tests on thermal deviation are performed in one 600 MW supercritical boiler. The issues associated with the safety of water wall, high temperature superheaters and reheaters are analyzed, and several solution measures are proposed.

Abstract:This paper firstly introduces the capacity, proportion and type distribution of the denitration facilities utilized in Jiangsu province, and then analyzes the present operation situation of the existing denitration facilities combined with real data obtained by the on-line monitoring system. Finally, according to the various problems encountered during operation processes of denitration facilities, some supervision countermeasures are proposed.

Abstract:Standardization plays a decisive role for the development and promotion of renewable energy technologies. Some international, regional, national and industry-specific standard-setting organizations are introduced, and the progress of international standards for renewable energy is elaborated. At last, China's participation in international renewable energy standards forming is analyzed, and recommendations for China's standardization work in the renewable energy are provided.