Dynamic Line Rating Research Articles

간접도체 방식을 이용한 가공송전선의 동적송전용량 추정

고가공도체의 최대허용전류인 열용량은 일반적으로 IEEE P738 기준에서 주어진 것과 같은 열평형 방정식을 기초로 계산된다. 이 정격은 기온, 풍속, 풍향 및 태양열과 같은 기상조건의 함수로 주어진다. 이러한 기상 파라미터들 중에 풍속은 그 값이 아주 작게 나타날 때 송전용량 결정에 강한 영향을 준다. 따라서 송전용량 모니터시스템에서 사용되는 풍속계 대부분은 낮은 감도와 실속 특성을 가지므로 부정확한 결과가 나타난다.br/ 본 논문에서는 풍속계를 사용하지 않고 가공송전선의 동적송전용량을 결정하기 위한 새로운 방법을 도입한다. 풍속을 2개의 간접도체의 온도로 추정하고 실험을 통하여 추정풍속으로 구한 동적송전용량이 기상모델로 구한 결과와 매우 근접함을 밝혔다.

Optimizing Transmission Path Utilization in Idaho Power

A new line current profile based dynamic line rating system has been implemented at Idaho Power Company by real-time exchange of data with Energy Management System and real-time weather data from the Internet. Increased utilization of transmission critical path is made possible by wide-area real-time dynamic rating using Internet based weather data. Economic analysis shows significant benefit of operating transmission lines at higher ratings by taking advantage of favorable weather conditions during overload conditions. A case study of an internal transmission interface including the Brownlee East path in Idaho Power using the new dynamic line rating system and an associated overload mitigation system is presented. It is shown there is minimum risk of overloading a circuit by increased transmission path utilization under N-1 contingency conditions.

Evaluation of an overhead line forecast rating algorithm

It is pointed out that a forecast rating scheme that accounts for the cyclic and random variation in ratings over time is essential to practical field application of dynamic overhead line rating. In principle, dynamic line ratings apply only for the instant in time in which the field data are measured. As time proceeds, the likelihood that the dynamic line ratings continue to remain valid diminishes. The authors evaluate a forecast rating scheme and identify the degree of conservatism that must be applied if dynamic line rating is to be a viable field concept. Specific forecast ratings are evaluated, and the advantages of dynamic line and forecast ratings over static rating guidelines are enumerated. >

On selecting transmission lines for dynamic thermal line rating system implementation

The author presents a systematic approach to: (1) selecting the candidate lines on which an implementation of a dynamic thermal line rating (DTLR) system will have the biggest return; and (2) determining the economic value of this undertaking. To develop this approach, information about contingently overloaded lines, which have the biggest impact on the penalty for off-cost generation, and about individual fuel cost, savings from implementing a DTLR system on each one of these lines is needed. To get this information, the approach is divided into two steps. Step one is for screening of contingently overloaded lines and ranking the severity of the overloading conditions of these lines. Step two is to determine the fuel cost savings from the uprating of these lines. Details of these steps are given. Analytical tools used in the two steps are the same as those used online in the control center.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Ambient temperature corrected dynamic transmission line ratings at two PG&amp;E locations

An offline ambient temperature corrected transmission line (T/L) dynamic thermal rating system is being developed at PG&E (Pacific Gas and Electric) to provide T/L ratings 1 to 24 hours ahead based on hourly ambient temperature measurements at a given location. A low minimum 2 ft/s constant wind speed is assumed at all times. Solar radiation is calculated by an analytical solar model assuming clear sky conditions. The IEEE/ANSI ampacity standard is used to calculate T/L ampacity. In the ambient corrected DTR (dynamic thermal rating) system, a stochastic/deterministic model forecasts ambient temperatures. The forecasts and the standard deviations of forecast errors are updated every hour. T/L ratings were evaluated at PG&E locations and gains of up to 34% over the static line ratings were possible at both locations by the proposed DTR system. The benefits and the risk of the ambient corrected DTR system have been quantified.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Dynamic line rating in the operating environment

The authors present power line data and dynamic line rating statistics obtained during a one-year study in new York State. Conclusions from the study apply specifically to the Porter/Rotterdam line Hash 30. Dynamic line ratings, defined as the minimum dynamic rating for the power line, were 20% lower than the average or single-station ratings. The greatest gains to dynamic line rating come from the limited time or transient rating. Limited time dynamic ratings derive their added benefit from the use of actual preload conductor temperatures in the rating calculation rather than the 95 degrees C conductor temperature assumed by many utilities. A forecast rating algorithm is proposed for calculating power line ratings intended to remain valid over a defined period of time in the future with minimal risk. Based on the algorithm, the 4-h forecast ratings were found to be 12% lower on the average than dynamic line ratings.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Significance of the Conductor Radial Temperature Gradient within a Dynamic Line Rating Methodology

Transient and steady-state overhead conductor radial temperature differences were monitored indoors under controlled wind conditions and outdoors in a real-world setting with the intent of establishing the significance of the radial temperature gradient within a dynamic thermal line rating methodology. The study validates steady-state and transient conductor temperature difference expressions developed by General Electric and utilized within DOLMIRS (a dynamic thermal line rating software package developed for NMPC and ESEERCO of New York State). The study substantiates the relative importance of the conductor temperature gradient especially when meteorological factors such as wind or ambient air temperature become more favorable toward higher dynamic ratings.