Power Transmission Facilities Research Articles

QoS-based dynamic channel selection algorithm for cognitive radio based smart grid communication network

Smart Grid (SG) operation requires multi-way communication among power generation, transmission, distribution, and consumer facilities. The complete SG architecture involves multiple layers of networks stretching from energy control center to consumer facilities and multiple applications with diverse Quality-of-Service (QoS) requirements. To meet these requirements, Cognitive Radio (CR) which offers efficient spectrum utilization and sharing, has been considered as a favorable solution. Due to diverse requirements of latency, data rate and reliability, it is a great challenge to support various SG applications under spectrum sensing uncertainties, Signal-to-Noise Ratio (SNR) variations and availability of desired channel bandwidth. In this paper, we propose a dynamic channel selection algorithm based on Fuzzy Inference System (FIS) capable of selecting the most appropriate available idle channel with desired bandwidth, minimum required SNR and probability of miss detection Pmd. The proposed algorithm utilizes various modes of IEEE Standard 802.22, Wireless Regional Area Network (WRAN), at the physical layer. In case of unavailability of idle channels with required SNR and/or Pmd, we propose a novel approach to select the channel with closest possible parameters aiming to reduce the re-transmission probability and thus achieve the desired throughput, latency and reliability requirements. The performance is compared with existing algorithms to demonstrate the effectiveness and superiority of the proposed algorithm.

A Study on the Regulation of Infringement and Compensation for Power Transmission Facilities

A Study on the Regulation of Infringement and Compensation for Power Transmission Facilities

Is the Korean public willing to pay for a decentralized generation source? The case of natural gas-based combined heat and power

Natural gas (NG)-based combined heat and power (CHP) plants can be installed near electricity-consuming areas and do not require large-scale and long-distance power transmission facilities. This paper attempts to assess the public's additional willingness to pay (WTP) for substituting consumption of a unit of electricity generated from nuclear power plant, currently a dominant power generation source in Korea, with that produced from NG-based CHP plant in terms of decentralized generation using the contingent valuation (CV) method. To this end, a CV survey of 1,000 households was implemented. The results show that the mean additional WTP for substituting nuclear power plant by NG-based CHP plant is estimated to be KRW 55.3 (USD 0.047) per kWh of electricity, which is statistically significant at the 1% level. This value amounts to 44.7% of the average price for electricity, KRW 123.69 (USD 0.106) in 2015, which implies that the public are ready to shoulder a significant financial burden to achieve the substitution. Moreover, the value can be interpreted as an external cost of nuclear power generation relative to NG-based CHP generation, or as an external benefit of NG-based CHP generation relative to nuclear power generation with a view to decentralized generation.

Power Flow Adjustment Planning Using Phase Shifting Transformers for Long‐Term Generation Outages

SUMMARYHigh growth in electricity demand during the period of Japan's bubble economy resulted in the construction of many power transmission facilities, including some loop systems. In some loop systems, there is a possibility of considerable power flow differences between heavy and light loads. Significant changes in the power system, such as from damage due to a natural disaster, would likely result in even larger differences and ineffective use of the loop system. Phase shifting transformers (PSTs) are highly efficient equipment for solving such power flow problems and some studies of operation methods using active power flow sensitivity (APFS) have been carried out. Calculating APFS, however, requires using the dc method. Since doing so requires the fulfillment of several assumptions, errors may appear in the calculation results. This paper assumes protracted significant local loss of generation capability (about 20% of total capacity), and examines the resulting load changes in the loop system. We then propose use of PSTs to alleviate load differences among transmission lines, allowing more effective use of the loop system. Specifically, we propose the concepts of APFS and active power flow sensitivity 2 (APFS2). Installing PSTs at optimal locations and operating the PSTs with proper phase angles determined by a branch and bound method, we mitigate loading differences between heavily and lightly loaded transmission lines. The validity of the proposed method is confirmed by using a modified IEEJ EAST 30 model.

Public Relations as Discourse Struggles An Analysis on the Construction Conflict of Power Transmission Facilities in Milyang-city

Public Relations as Discourse Struggles An Analysis on the Construction Conflict of Power Transmission Facilities in Milyang-city

Safety awareness educational topics for the construction of power transmission systems with smart grid technologies

Power transmission facilities in the U.S. are undergoing a transformation due to the increased use of distributed generation sources such as wind and solar power. The current power grid system is also antiquated and in need of substantial retrofits to make it more efficient and reliable. The new energy transmission system being designed and built to optimize power delivery is known as “Smart Grid”. The increased activity in the construction of power transmission facilities and installation of new technologies into the current power system raises potential safety concerns. Existing construction management curriculum may include general information about safety training, but does not typically include information about this specialized sector. The objective of this study was to work with industry to identify key safety topics appropriate for inclusion in an introductory industrial construction course. Results of interviews with industry identified numerous hazards that are not typically covered in typical construction curricula. A joint undergraduate and graduate course in industrial construction was created to address these and additional concepts. A survey of the students was performed to determine the effectiveness of the course and also to determine their thoughts about the smart grid technologies and safety training. Information on electrical system hazards is presented along with results of the student surveys.

A Vision-Based System for Power Transmission Facilities Detection

In this paper, we present the design and implementation of a vision system for power transmission facilities detection based on UAV videos. The vision system consists of two main parts, the client part and the server part. The aim of the system is to detect the power transmission facilities in complex background. In order to achieve this aim, several novel methods are proposed for detecting the power transmission facilities which include the power line, the power tower, and the insulator. The experiment results on real image data demonstrate that the proposed methods are accurate and effective. The system is presented to demonstrate the performance of the detection methods.

스위칭 속도 및 온도 제어를 사용한 고압용 정지형 무효전력 보상장치의 안정화

본 논문에서는 고압용 정지형 무효전력 보상장치의 스위칭 모듈의 속도 제어 및 온도 제어 기법을 제안한다. 지속적인 전력 수요의 증가에 따른 발전 설비 및 송 배전설비의 신규 건설이 요구되고 있으며, 전력수송설비의 신 증설로 전력수송로의 병목현상에 따른 문제점이 나타나고 있다. 따라서 기존설비의 이용률을 극대화하고, 신규건설 없이 송전용량을 증대시키는 방안이 연구 되고 있다. 기존의 정지형 무효전력 보상장치 제어 방식에서는 전원입력회로에서 전위 검출하여 SCR를 직접 스위칭 동작하게 되어 있어서 노이즈가 발생하게 된다. 제안한 방법은 SCR 양단의 전위차를 바탕으로 스위칭 제어하여 스위칭 속도가 향상되고 노이즈가 감소하게 된다. 또한 스위칭 속도 증가로 발생하는 발열을 실시간 온도 제어함으로 안정성을 향상하였다. 실제 실험 환경을 구성하여 제안한 고압용 정지형 무효전력 보상장치의 속도 및 온도 제어를 실험하고, 실제 현장에서 성능을 검증하였다. 제안한 고압용 정지형 무효전력 보상장치의 스위칭 모듈을 통한 온도 제어를 실험하고, 실제 현장에서 성능을 검증하였다. In the paper, velocity controller of switching module and temperature controller for the high-voltage static var compensator are proposed. Because of the continuous increase in demand for electric power, transmission and distribution facilities of power plant are required. There is a bottleneck problem of transportation routes according to new construction and expansion of power transmission facilities. Therefore there are researches to maximize the utilization of existing facilities and to increase transmission capacity without new construction. The previous static var compensator detects voltage of input circuit of power, switches the SCR directly and generates switching noise. The proposed method increases switching velocity and decreases noise using switching control based on the voltage between both sides of SCR. Also the proposed method enhance the stability using realtime temperature control for heating of the system from increase of switching velocity. We experiment the velocity and temperature control of the proposed high-voltage static var compensator in the real environment and verify the performance of the proposed system by applying in the real field.

A Research for Site Detection Scheme for the High Temperature Superconducting Cable from the Electrical Point of View

This paper proposes an algorithm to search the suitable site for the installation of the High temperature Superconducting (HTS) cable. The HTS cable is able to transmit a large amount of electricity without additional power transmission facilities. However, it is not desirable to install the HTS cable anywhere because the HTS cable is the high price facility. The best location for the installation of the HTS cable is the place that congestion of transmission line is occurred in. If the HTS cable is used in congestion area, an additional transmission facility is not necessary for stable operation of power system. The technology level of the HTS cable has been improved consistently so the installation of the HTS is possible to use in the limited part of power system. In this paper, an algorithm is suggested to search the proper place for the HTS cable and verified by case study in the power system.

Research on the feature extraction of DC space charge behavior of oil-paper insulation

As the ultra high DC voltage grid comes into an important stage in the ‘Twelfth Five-year Plan’ of China, the requirement on the operation safety of power equipment needs to be improved. Oil-paper insulation plays a significant role as the main insulation material of many key power equipments. The space charge behaviors of oil-paper insulation not only affect the dielectric strength, but also relate to the stability and security of power transmission facilities. Until now, the research on the space charge behaviors of oil-paper insulation remains on the stage of objective description and phenomenon explanation, thus it is very urgent to make some feature extractions on the test results in order to further investigate the DC space charge behaviors of oil-paper insulation. In this paper, based on the large numbers of test data in the first stage, data mining and feature extractions were performed on the DC space charge behavior of oil-paper insulation. The variation laws of some key characteristic parameters obtained in different experiment conditions such as the total charge injection amount, apparent charge mobility, and trap energy distribution were analyzed. In addition, the distribution of trapping level inside oil-paper was calculated by using the PEA test results based on the mechanism of the isothermal decay current, which realized the approximate calculation of trap depth by charge decay characteristics. What’s more, the exponential injection and decay equations of DC space charge changing with time were acquired for the first time, and the physical meanings of related parameters were defined. This has laid a foundation for the prediction and simulation of space charge in the oil-paper insulation.

An on-line training radial basis function neural network for optimum operation of the UPFC

The concept of Flexible A.C. Transmission Systems (FACTS) technology was developed to enhance the performance of electric power networks (both in steady-state and transient-state) and to make better utilization of existing power transmission facilities. The continuous improvement in power ratings and switching performance of power electronic devices together with advances in circuit design and control techniques are making this concept and devices employed in FACTS more commercially attractive. The Unified Power Flow Controller (UPFC) is one of the main FACTS devices that have a wide implication on the power transmission systems and distribution. The purpose of this paper is to explore the use of Radial Basis Function Neural Network (RBFNN) to control the operation of the UPFC in order to improve its dynamic performance. The performance of the proposed controller compares favourably with the conventional PI and the off-line trained controller. The simple structure of the proposed controller reduces the computational requirements and emphasizes its appropriateness for on-line operation. Real-time implementation of the controller is achieved through using dSPACE ds1103 control and data acquisition board. Simulation and experimental results are presented to demonstrate the robustness of the proposed controller against changes in the transmission system operating conditions. Copyright © 2010 John Wiley & Sons, Ltd.

Common insulating properties in insulating materials

Insulating materials exist in a variety of different forms, including gas, liquid, solid, and vacuum, and different forms of insulating materials have significantly different dielectric strengths and insulating properties. Power transmission/substation facilities for UHV AC and 500 kV DC power transmission and 500 kV underground power transmission facilities have been designed and constructed by taking advantage of the insulating properties of various insulating materials and structures so that they conform to the demanded insulation specifications. Conventionally, insulating material technology has been developed by making a close study of apparatuses and insulating materials individually. In this paper, as a new attempt, the insulating properties of various insulating materials/apparatuses are cross-sectionally compared and examined from an entirely new viewpoint through the assessment of commonalities and differences between them. A listing of lightning impulse and AC dielectric strength data is prepared and systematically positioned from the standpoint of material and structure, and compared and evaluated in a unified way from the viewpoint of typical indices of insulating properties including the "n" value of the V-t characteristic, Weibull parameters, and impulse ratio. Further, an insulation assessment of apparatuses is systematically made with consideration given to their sizes and structures as well as the insulating materials themselves. As a result, it was found, for example, that the design field strengths of power capacitors were high and those of generators were not, and there was a noticeable difference in design field strength between SF/sub 6/ gas insulated apparatuses and oil-immersed transformers. It is expected that the analysis conducted from an entirely new angle may provide a new approach to the development of apparatus insulation technology and to the rationalization of insulation design.

The interaction between ELF electric fields and RF survey meters: theory and experiment

An RF survey meter is often used to evaluate the safety of human exposure to RF electromagnetic fields. However, it has been noted that erroneous meter indications occur when the meters are used in strong, extremely low-frequency (ELF) electric fields, such as those found near electric power transmission and distribution facilities. In this paper, coupling between an ELF electromagnetic field and an RF survey meter has been studied theoretically and experimentally. It has been shown that coupling large enough to result in erroneous readings can be caused by unbalanced currents as small as 0.1% of the balanced currents on the transmission line that connects the probe to the readout unit. Unbalanced currents of this magnitude can be caused by capacitive coupling to the probe and readout unit.

Typhoon damage analysis of transmission towers in mountainous regions of Kyushu, Japan

In the 1990s, four strong typhoons hit the Kyushu area of Japan and inflicted severe damage on power transmission facilities, houses, and so on. Maximum gust speeds exceeding 60 m/s were recorded in central Kyushu. Although the wind speeds were very high, the gust factors were over 2.0. No meteorological stations are located in mountainous areas, creating a deficiency of meteorological station data in the area where the towers were damaged. Since 1995 the authors have operated a network for wind measurement, NeWMeK, that measures wind speed and direction, covering these mountainous areas, segmenting the Kyushu area into high density arrays. Maximum gusts exceeding 70 m/s were measured at several NeWMeK sites when Typhoon Bart (1999) approached. The gust factors varied widely in southerly winds. The mean wind speeds increased due to effects of the local terrain, thus further increasing gust speeds.

Contingency selection method for on‐line small signal stability monitoring

AbstractTo make greater use of existing electric power transmission facilities, security assessment utilizing on‐line data is thought to be one of the effective measures that can be taken. To realize on‐line assessment of postfault small signal stability for a number of supposed contingencies, it is effective to identify severe contingencies to be analyzed with a precise assessment program, such as the S‐method. We developed a contingency selection method that has two indices for selection.One of the indices is postfault eigenvalue estimation based on second‐order approximation of the eigenvalue change in response to system matrix change, which is effective for relatively weak nonlinear eigenvalue change. The other one is the Nonlinearity index, which indicates the strength of nonlinearity eigenvalue change. It is effective in detecting strong nonlinear eigenvalue changes that cannot be estimated correctly by second‐order approximation.Calculation results with IEEJ Bulk Power System Models show that the proposed method can effectively decrease the number of contingencies that must be analyzed by the precise Small Signal Analysis method. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 20–27, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10186

Aerodynamic drag of new-design electric power wire in a heavy rainfall and wind : Kikuchi, N. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2003, 91, (1–2), 41–51

The authors have studied out grooved round transmission wires, developing Model LP-810 wire with lesser drag. Aerodynamic characteristic of grooved round transmission wires were studied in wind-tunnel experiments. But being located outdoors, electric power transmission facilities are subject to the design limit loading in a strong wind, which, in most cases, is based on typhoon-weather conditions. Consequently, the wind-tunnel experimentation needs to attach a factor of rainfall to the simulated wind conditions (usual wind conditions). In this laboratory test, the authors set up a watering grid upwind in the wind-tunnel's test section, which simulated a number of rainfall: 0, 2, 4, 8, 10, 16, 25 and 40 mm per 10 min. Those rainfalls were rationalized, based on the domestic weather observation data: 10 min cumulative amounts of rain and 10 min mean wind speeds of time frame. Thus, LP-810 was tested under simulated, rational wind and rainfall conditions, and its design drag coefficients were figured out.

Aerodynamic drag of new-design electric power wire in a heavy rainfall and wind

The authors have studied out grooved round transmission wires, developing Model LP-810 wire with lesser drag. Aerodynamic characteristic of grooved round transmission wires were studied in wind-tunnel experiments. But being located outdoors, electric power transmission facilities are subject to the design limit loading in a strong wind, which, in most cases, is based on typhoon-weather conditions. Consequently, the wind-tunnel experimentation needs to attach a factor of rainfall to the simulated wind conditions (usual wind conditions). In this laboratory test, the authors set up a watering grid upwind in the wind-tunnel's test section, which simulated a number of rainfall: 0, 2, 4, 8, 10, 16, 25 and 40 mm per 10 min . Those rainfalls were rationalized, based on the domestic weather observation data: 10 min cumulative amounts of rain and 10 min mean wind speeds of time frame. Thus, LP-810 was tested under simulated, rational wind and rainfall conditions, and its design drag coefficients were figured out.

オンライン定態安定度監視のための事故選択スクリーニング手法の開発

To make more use of existing electric power transmission facilities, security assessment utilizing on-line data is thought to be one of the effective measures that can be taken. To realize on-line assessment of post-fault small signal stability for a number of supposed contingencies, it is effective to pick out severe contingencies to be analyzed with precise assessment program, e.g. S-method. We developed contingency selection method that has two indexes for selection. One of the indexes is post-fault eigenvalue estimation based on 2nd approximation of eigenvalue change for system matrix change, which is effective for relatively weak non-linear eigenvalue change. The other one is Non-linearity Index that indicates the strength of non-linearity of eigenvalue change. It is effective to detect the strong non-linear eigenvalue change that can not be estimated correctly by the 2nd approximation estimation. Calculation results with IEEJ Bulk Power System Models show that the proposed method can effectively decrease the number of contingencies that have to be analyzed with precise Small Signal Stability Analysis method.

Development of vanadium redox flow battery for electricity storage

There is serious demand today for superior technology for load levelling placed on power generation and transmission facilities. The vanadium battery, developed by Kashima-Kita, uses vanadium compounds as an electrolyte, recovered from boiler soot in Orimulsion-fired power stations to provide a solution to this problem. This battery is eminently suitable for load levelling, being operable at room temperature and normal pressure, easily convertible to a large scale and is environmentally friendly. In September 1997, Kashima-Kita built a 200 kW×4 hour-rate battery after having built both 2 kW and 10 kW prototype units. The battery is interconnected to the company's power plant grid system and has to date achieved 650 cycle continuous operation at the rated efficiency. This success has proved that a high-efficiency heat power station system equipped with such an electricity storage battery reusing byproducts of the power plant can be commercially viable.

Deregulated power system planning using a reliability network equivalent technique

In a deregulated or unbundled power system, generation, transmission and distribution facilities can belong to quite different owners. This situation makes it difficult for the system planners who work in the various companies to evaluate system reliability without access to the entire system. The paper provides a technique based on reliability cost-worth considerations. The technique can be used to make utility planning and operating decisions and by customers to make purchase decisions in an unbundled utility regime. The concept of a service provider is introduced to represent generation and transmission facilities. Reliability equivalence techniques are used to determine a representative service provider and to create equivalent elements. Some of the problems in an unbundled power system are illustrated using a representative test system.