Network planning evaluation implementing time varying thermal ratings

Abstract

Abstract-Contemporary transmission networks are not fully utilized due to increased uncertainty and security buffers resulting mainly from the inefficient operation and planning, currently based on conservative predetermined thermal ratings. However, in a smart operation scheme, which considers time varying thermal ratings of transmission assets, operation and planning could be optimized to facilitate the proliferation of generation expansion projects while maintaining required levels of reliability. This paper presents a methodology which enhances the current methods of network element ratings by incorporating a more detailed modelling of the overhead line (OHL) properties. Three thermal rating models, static (STR), seasonal (SeTR) and time varying (TVTR), are implemented for comparative studies, under both deterministic and probabilistic frameworks with an aim to identify the most cost-effective and optimal flexible network operation plan in today's congestion-driven and competitive power markets. In addition, the effects of line outages on transmission losses in the electric power networks are presented, quantifying the transmission losses in a realistic manner due to the incorporation of real thermal ratings. The IEEE 24-bus RTS is used under sequential modeling to validate the methodological enhancements and to evaluate network performance. The system annual operating costs are reduced when using the proposed TVTR model.

Electricity Network Reliability Planning and Evaluation Considering Flexible Solutions

“…Therefore, in order to determine the true transmission capacity that is available on a given network, the methodology to incorporate time-varying thermal ratings (TVTRs) used in this work is taken from [13], which uses an iterative algorithm that considers the TVTR in an annual basis. This behavior is augmented to the process of step 4 of the discussed reliability evaluation methodology in section A More explicitly, the annual chronological load curve can be used with the annualized TVTR values.…”

“…In detail, the TVTR model proposed in [13] is used to represent the real transmission capacity that is available on a given network. The wind speed (Vm), direction (Kangle), and ambient temperature (Ta) are used for the modeling of the OHL adequacy.…”

“…This paradigm is associated with the proliferation of power systems technologies that promise to enhance its flexibility amid uncertain operating environments, for example, through the influx of renewable generation. Examples of flexible solutions include: ageing of overhead line (OHL) [9], demand side management [10], special protection systems with ICTs [11], wind farms [12], FACTs [12] and time varying thermal rating (TVTR) [13].…”

MOPSO using probabilistic and deterministic criteria based on OHL's thermal ratings

“…The TRs are set on the MOPSO algorithm as it is shown in the flowchart of Fig.1 through the "assessing the dominant cases" step. It should be stressed that in the analysis the T c is set at 95 o C based on the avoidance of the conductor annealing [30] [31].…”

Impact of thermal uprating and emergency loading of OHL networks on interconnection flexibility

“…There are several methods with which increased power rating through "hot wiring" can be achieved, such as reevaluating the OHL design for conservatively rated lines or advancing the thermal rating method used to perform the initial calculations. Therefore, implementing different rating models, such as seasonal line rating (SeLR), probabilistic line rating (PLR) or time varying line rating (TVLR) [8][9][10][11][12][13][14] can result in increasing the power transfer capabilities of the same OHL with no additional cost. When PLR OHL modeling is implemented to increase power delivery of the same OHL, then an increased risk of overheating the conductor is considered in the design.…”