Abstract:This paper pays attention to three mature types of online monitoring devices, namely transformer oil chromatography, dc magnetic bias and insulator pollution degree, which have high data availability. The principles of monitoring devices are illustrated in the paper. By practical application cases, the status of online monitoring devices utilized in Jiangsu power grid transmission and distribution system are analyzed. The result of analysis shows it is necessary to improve the reliability of online monitoring device and to strengthen the relationship between online monitoring data and fault defects detection which will promotes the intelligent development of online monitoring devices.

Abstract:The conventional automatic generation control (AGC) strategy only takes the economic factors into consideration. However, for interconnected power grids, the hidden failure of communication outage may cause AGC control signal blocks followed by control units' inability of power adjustment with the load fluctuation. In this paper, a novel AGC strategy was proposed to improve the conventional one by taking both strategy of economic dispatch (ED) and load frequency control (LFC) into consideration. The novel AGC strategy has considered the communication outage probability and was prophylactic, so that it could let the impact of communication outage down. The ED control of the novel AGC strategy was designed against the long-term substantial load fluctuation by adjusting the power of those AGC units with high communication outage probability according to the load forecasting as much as possible. While the LFC strategy of the novel AGC strategy was designed against short-term and unpredictable slight load fluctuation by adjusting the power of those AGC units with low communication outage risk. The IEEE-118 system is employed to verify the effectiveness of the novel AGC strategy. The simulation results indicate that the novel control strategy has the ability of improving the dynamic stability of power system, excellent economy and engineering application value.

Abstract:The paper proposed a partitioning method of substation service areas based on weighted K-means clustering algorithm, based on which substation planning algorithm was put forward further with genetic algorithm. The algorithm determines the optimal combination of the number of substations and main transformers and the capacity of main transformer by the global searching ability of genetic algorithm, which solves the problem of determining initial clustering number when partitioning substation service areas by weighted K-means clustering algorithm. The weighted K-means clustering algorithm can comprehensively meet the constraints of load ratio and supply radius of substation and take adaptive adjustment during iteration. The example shows that the proposed algorithm can serve for substation planning well.

Abstract:In China, a 500 kV/1000 kV AC quadruple-circuit transmission line will be constructed in the near future. This kind of line has multiple operating modes and complicated arrangement forms, which results in complex electric potential and field distributions. To study the effect of transmission line on surrounding electromagnetic environment, the electric field distributions around the surfaces of conductors and earth wires and under transmission line in eighteen typical operating modes and a fundamental frequency circle are calculated, and then the conductors and earth wire configurations are optimized. The results show that the maximum electric field intensities on the surfaces of conductors are about 2500 kV/m, and on the earth wires are about 3100 kV/m; and the electric field intensities on the surfaces of conductors equals to the ones of the earth wires when the diameter of earth wire are 25 mm. The conductors and earth wires are suitable for the altitude of line located less than 1.2 km, in such a case the maximum electric field intensity in the space above the ground and below the lines is lower than 4 kV/m which is up to standard.

Abstract:The ultra-high voltage transformer is one of the key equipment, and its electromagnetic transient simulation model is the basis for relay protection research. Through analyzing the principle of 1000 kV UHV transformers, and considering the winding connection characteristics, a main part and voltage regulation and compensation part integrated model is established in PSCAD/EMTDC. The simulations and analyses on normal operation, no-load switching and short circuit condition are implemented.

Abstract:With the continuous development of power industry, 1000 kV UHV transformer is more and more widely used. To meet the extra high-voltage electrical equipment field testing requirements, according to the testing items, testing methods and criteria in the Standard for acceptance testing of 1000 kV electric equipment in engineering, the structure and wiring characteristics of UHV transformer are analyzed and the 1000 kV UHV transformer rapid testing method based on controlled switching is studied. Then, the testing system, with one-time connection and intelligent measurement, analysis and judgment ability, is designed. The testing system avoids the problems of multiple-time connection, time consuming and low efficiency.

Abstract:Considering the heavy workload, inefficiency, low safety, time-consuming in data analyzing and processing in transformer substation start debugging, a distributed wireless synchronized measurement and recording system for the start debugging of transformer is developed. The system is simple, efficient, safe, reliable and intelligent. The developed system has been applied to the transformer substation start debugging in Jiangsu electric power company, and the results satisfy the technique requirements. Compared to traditional wave recorder system, the wireless synchronized measurement and recording system has a better user-experience. The application of this system increases start debugging experiment and enhances the efficiency and safety of start debugging.

Abstract:The infrared temperature measurement technology is widely used in detecting and repairing electrical equipment, but hasn't been used in substation start-up and commissioning. In this paper, the infrared temperature measurement technology applied into the start-up and commissioning of ultra-high voltage project in two engineering cases are introduced. Finally, the problems of and corresponding suggestions to infrared temperature measurement technology for start-up and commissioning are proposed.

Abstract:Unified power flow controller (UPFC) consists of two parts, namely series and parallel converters. When faults happen on the line near the two parts, converters respectively at the series side and parallel side will be both affected. The UPFC must have the ability against the line instantaneous fault, and the ability to continue running after the fault is cleared. Artificial short circuit test can test the fault ride-through capability of UPFC. The parameter design of main equipment and strategy against faults of Nanjing UPFC pilot project are proved reasonable by the analysis of the artificial grounding test results.

Abstract:To solve the problems such as false root judgment, astringency, high computation cost and so on, which exist in asynchronous dual-terminal fault location algorithms, this paper presents a new fast and accuracy dual-terminal fault location algorithm for HV transmission line. Based on the line distributed parameters and the analysis of the monotonicity and periodicity of HV transmission line's voltage amplitude curve, it automatically identifies the false root according to the variation tendency of fault point's voltage in the process of iterations, so that the next search direction can be determined. Then the fault point is rapidly located by dichotomy. This algorithm is simple with minor calculation. It also doesn't require synchronous dual-terminal data and can eliminate the influence of transition resistance. So it has a high practical value. The simulation results of PSCAD show that it overcomes deficiency of the former algorithms and has high accuracy and quick computation speed, resolving the contradiction between rapidity and false root judgment.

Abstract:The zero sequence directional component gives the wrong judgment when ground faults occur on the other line of the parallel transmission lines with magnetically strong and electrically weak connection. Focused on the problem, the characteristics of voltage sequence components under different faults are analyzed. Based on different voltage sequence components, a new zero sequence directional component is proposed in this article. Considering the different types of faults, the new zero sequence directional component takes the synthetic value of zero sequence voltage and positive sequence voltage as the reference voltage of phase comparison. The new proposed zero sequence directional component can distinguish the fault direction correctly for parallel transmission lines with magnetically strong and electrically weak connection, preventing the unwanted operation of the pilot zero sequence directional protection. The simulation by PSCAD verifies the effectiveness of the new directional component.

Abstract:The foreign body cleaner based on directed energy laser is a new type of foreign body removal tool which is effective, safe, convenient, and practical. It can remove foreign bodies of overhead transmission line remotely under live working condition. When the laser device cleans foreign bodies, the local temperature rise of wire may happen, followed with local damage of wire or abnormal operation of power transmission line. Theoretical analysis and multi-physics finite element simulation are carried out to study the local temperature variation and temperature field distribution of wire under laser action. The simulation results show that the laser absorption rate and the wire diameter have great effect on wire temperature during the laser action on wire. The simulation results of laser irradiating aluminum cable steel reinforced (ACSR) LGJ-300/50 show that the laser irradiation can result in local temperature rise with the upper limit of 170℃ ,and the local conductivity of current carrying conductor has an uneven distribution related with temperature.

Abstract:The intelligent distribution network is becoming more and more flexible, reliable, efficient and multivariate. As the strong source-grid-load triple asymmetry in the distribution network is increasingly prominent, the traditional empirical dispatching method can't fully control the operation state and development trend of distribution network. In this paper, the overall framework of three phase operation simulation technology of the intelligent distribution network with the source-grid-load asymmetry is put forward. Secondly, the steady and transient three-phase models of key components are established and the three-phase power flow is calculated. On these basis, the three-phase node voltage short-circuit calculation and steady/transient simulation technologies are thoroughly studied. Finally, an operation simulation platform is developed based on the OPEN3200, and successfully applied to Nanjing Hexi CBD which verifies the rationality and the effectiveness of the proposed methods.

Abstract:According to the technical characteristics of UHV AC substation monitoring and control system, it is firstly analyzed the architecture of the substation monitoring and control system. Based on the demand for testing it is summarized the testing items of the substation monitoring and control system, mainly including the measurement and control device function and performance testing, monitoring and control system function and performance testing, data communication gateway function and performance testing, network message analyzer function test, time synchronization online monitoring function, protection device access monitoring and control system testing, system switching function testing. And then it is put forward a new test method of monitoring and control system based on the combination of SCD model simulation and physical objects. Finally, with the gang tuning testing experience of UHV AC substation monitoring and control systems in actual project, the problems found in the testing are analyzed and countermeasures are given. The analysis of the test technology application will have some reference value for the construction, debugging, operation and maintenance of UHV substation monitoring and control system in the future.

Abstract:Since a large number of distributed generators access to low-voltage distribution network, the power system is easy to become an islanded and enter an instability state with low power quality. When the power supply is far less than the load demand (there is large power shortage), it's the key making the island return from instability state to normal state by improving the coordination scheme of protections. Based on the allocation status of the under-frequency load-shedding device and the backup power automatic throw-in device in low-voltage distribution network, it is proposed an island self-healing scheme without extra investment for smart distribution network which is different from the traditional setting scheme for the two protective devices. Under the condition of giving priority to ensuring units safety, the proposed scheme improves the prior setting scheme which can get the optimal unit safety and make distributed generators access to power grid without any loss of power supply and load. The simulation of a fault case in actual grid proves that the proposed scheme improves the reliability of power supply and avoids units' instability state. It has great application value in engineering, and now has been applied to Jiangsu Power Grid.

Abstract:With a number of distributed generations (DGs), microgrids and diverse loads accessing to power grid, the form of source-grid-load friendly interaction becomes diverse. The communication network scheme and security protection strategies also face new challenges. On the basis of introducing the general network scheme of source-grid-load friendly interaction system, this paper discusses in detail the security protection strategies and communication network scheme with the access of big consumers' security & stability defense control, marketing production control area, marketing management information area, big interruptible consumers, etc. At last, the communication network scheme of source-grid-load friendly interaction system are verified to be feasible and effective through the practice of the source-grid-load project in Jiangsu.

Abstract:Synchronous voltage signal of short circuit generator needs to be gathered in the high power testing, in order to meet the closing phase angle control requirements in high voltage circuit breaker test process. Affected by environmental temperature, the measuring way controlled by AC/DC generator is prone to temperature drift, low accuracy and big volume, so it is gradually replaced by digital measurement way. Compared with the control generator scheme, the full digital control method based on the encoder has obvious advantages. A new speed and phase measurement scheme of short circuit generator based on the incremental encoder is designed in this paper. And the principle, structure, advantages of the scheme and the signal anti-interference problem are introduced. With this method, the speed and reference phase signal accuracy and precision of the short circuit generator are improved, which gives the foundation for closing phase angle control of large capacity test process.

Abstract:A novel fault location principle with asynchronous data is proposed to solve the asynchronous problem of fault location at both ends which can't be ignored. The primary dual-terminal synchronous fault location equation is asynchronized in the principle by taking conjugate complex number at both sides of the equation simultaneously, which transforms the equation into a set of equations with two unknown variables of fault location and asynchronous angle. The set of equations can be transformed into a quadratic equation with one variable which can be solved to reach the goal of asynchronous fault location. Simulations show that the proposed asynchronous fault location method can eliminate the asynchronous angle and has high precision which is hardly affected by transition resistance, so it is adequate for all short circuit faults.

Abstract:The application of new technology involved became universal with the increasing production number of smart substation. Compared with the traditional substation, the smart substation owns some new IEDs (Intelligent Electronic Devices) such as electronic transformer, merge unit, intelligent terminal and network analyzer. The cable between the secondary devices was canceled and replaced by the network transmission packet consisting of the optical fiber, the process layer switch and the station control layer switch. The redundancy configuration of the secondary equipment was also different. The differences of secondary AC circuit, maintenance mechanism and reclosing circuit between traditional substation and smart substation were focused on by the article. It was also described that the new technology applied in the smart substation had a deep effect on the operation and maintenance on site.

Abstract:The paper emphatically elaborated the design and implementation technology of WEB graphics based on extensible architecture with SVG (Scalable Vector Graphics) as the core. To realize the technology, power system graphics library and unified SVG graphics publishing format were studied and set up based on the SVG standard. Besides, the R&D applied interface call technology and structured message communication mechanism across different languages. What's more, asynchronous communication mechanism of WEB graphical data was achieved based on server pushing technology. The SVG and scalable WEB graphics system help effectively solve the problem of strict requirement for real-time performance when the model information is dynamically refreshed, improving the level of WEB graphics applied to power grid operation control system. Now the SVG and scalable WEB graphics system has been applied in practice.

Abstract:Comparative analysis has been done on the characteristics, line selection methods and application range of different neutral grounding modes including ungrounded, grounding through arc suppression coil, grounding via small resistance and grounding through arc suppression coil and line-selecting resistance in parallel. The paper discussed in detail about the work principle, the line-selecting resistance selection principle and the lockout protection configuration principle of the last neutral grounding mode through arc suppression coil and line-selecting resistance in parallel. The neutral grounding mode through arc suppression coil and line-selecting resistance in parallel can improve the self-recovery probability from single-phase ground fault and achieve the single-phase ground fault line detection, which make it an ideal grounding mode for urban Power Distribution Networks.

Abstract:Several converter-transformer failures occurred in succession in Zhengping converter station. Strip inspection analysis of these failures has been done considering the location of partial discharge and insulation pollution. The analysis show these failures mainly resulted from the open-type design of oil conservator for the converter transformer. During the long-term operation of the converter transformer, the insulating oil is easily oxidized and affected with damp, bringing in impurities. Besides, the design of thermal expansion and contraction alternating and oil drain at the bottom of the tank may get the oil extra water and the transformer impurities. The design defects can cause rust strains on the appearance of the iron core facing the oil filler of the conservator, partial damp of the insulating press board, as well as edge pollution of the upside iron yoke. Then Partial discharge will occur, followed by converter-transformer failures for qualitative change is caused by quantitative change.

Abstract:A 220kV line tripped caused by the fracture of composite cross-arm insulator, the main reason of which is found out that the structural strength of the insulator is insufficient. Besides, for the lack of test, some composite cross-arm insulators with design defects have been applied to the power grid, bringing hazard to the power grid, and need to be investigated and rectified. Therefore, the structure strength calculation and design method of composite cross-arm insulator were discussed. It was proposed that the bending stress of composite cross-arm insulator should be calculated according to the weight of the insulator itself, the weight of fixed conductor and the designed wind load in the process of design and manufacture. A suggestion was also proposed that when components with non-central symmetrical section were used to connect composite cross-arm insulator to tower, the installation direction must be explicit, so that the structural force was within the limits.

Abstract:Denitration transformation was conducted in the No.1 boiler A of one power plant during May, 2012. Ammonium bisulfate was accumulated in the low temperature air preheater section after the spring festival of 2013 and 2014, resulting in the rising differential pressure in the gas-side of air preheater, and this problem was solved by washing of the supported high-pressure water flushing system. This paper focused on the situation of large deviation, improvement measures as well as the economic analysis of solving the large deviation of the denitration flow after running the denitrification system in No.1 boiler. Thus, the present study could provide a reference for the denitration transformation of other power plants.

Abstract:Currently, the coal consumption rate and fuel loss rate of the coal-fired power plants were isolated and they also had some limitations. Based on the operation and management, this paper proposed a new indicator of coal consumption of power plants, including both the economic indicators and the fuel management indicators. According to the incoming fuel acceptance data, the fuel inventory data and electrical energy metering data, the obtained indicator is accurate and can be used as a comprehensive energy consumption indicator. Further, the resulting fuel loss could be used as a comprehensive fuel loss indicator for the fuel quantity and loss of heating value between incoming and incoming furnaces.

Abstract:As a vibration isolation device for the foundation of large steam turbo-generator, the bearer installation quality of spring vibration isolation directly affects the successful installation and stable operation of the steam turbo-generator. At present, the bearer of spring vibration isolation is widely used in the power plants of some countries like Germany and Russia. Although the bearer of spring vibration isolation is less used in domestic, the application has a trend of development day by day. Based on the construction supervision work for the bearer installation of spring vibration isolation used as the foundation of the 2×1000 MW steam turbo-generator of Tianwan nuclear power plant in Lianyungang, the method and the key of quality control in the whole process including raw material inspection, the bearer prepressing and installation of spring vibration isolation and the installation of the prepressing portal were summarized. Practice proves that the bearer prepressing and installation of spring vibration isolation for Tianwan nuclear power station in Lianyungang meet the requirements of design and manufacturer, and the quality is under control.