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Methodology for Analysis of Dynamic Line Capacity
and Optimized Management of Electric Grids


(PTDC / EEI-EEE / 31711/2017)

FCT

About

This project aims the development of a methodology and an operational tool for the Dynamic Line Rating (DLR) analysis of potentially congested electrical networks for optimal integration of renewable energy sources (REs) in a cost-efficient way. DLR steady-state analysis is traditionally used to assess the seasonal capacities of power systems lines. The OptiGRID project will demonstrate the benefits of using DLR techniques namely in terms of 1) increasing the RES penetration levels and reducing the need for curtailment in the power system and 2) reducing the number of market splitting hours in the Electricity Market and consequent impact on electricity market prices, thus contributing to a more sustainable, energy and cost-efficient economy. The implementation of DLR analysis will play a key role in increasing RES penetration levels into the existing power system, without requiring grid reinforcement. The resulting additional power line capacity from DLR analysis alleviates congestion problems and allowing higher levels of distributed RES capacity in the power system. This becomes of particular importance in systems with high generation of wind power (as in the Portuguese case) because of the existing correlation between the higher line rating and the increased wind power generation achieved under high wind speed conditions, where the extra cooling effect of wind speed provides the alleviation of congestions and the consequent accommodation of higher wind power levels.

Schematic representation of a quasi-stationary approach for DLR analysis of potentially congested networks.

Although the benefits of applying DLR techniques have local nature and depend on weather conditions, preliminary studies indicate an increase of the line capacity up to 20%, significantly more than the one obtained by the usual conservative static approach. This increase on the line capacity is also important for system operators concerning power exchanges with neighbouring countries. The Import/Export capacity is dependent on some relevant branches (not only the tie-lines) which will benefit from the increased capacity allowed by applying DLR techniques. This is especially important when the power exchanges limited by line capacity may cause a market split with an impact on the corresponding market prices. The envisaged tool will allow the assessment of DLR analysis facilitate massive integration of RES considering not only actual operational conditions, topology, and electrical characteristics of the transmission network (TN) but also the foreseen expansions of the TN accommodating higher renewable levels. Suitable case studies will be developed under OptiGRID considering current and future scenarios of high RES penetration levels in the power system, as well as different constraints.

Characteristics
This work is funded by national funds through the FCT – Fundação para a Ciência e a Tecnologia, I.P., under the grant PTDC/EEI-EEE/31711/2017.

Project Financial data

Date of approval: 06.07.2018
Total eligible cost: 239.874,06€

Project Duration

Start date: 01.10.2018
End date: 30.09.2021

Project

Objectives
The goal of this project is the development of a methodology and an operational tool for the Dynamic Line Rating (DLR) analysis of potentially congested electrical networks to allow an optimal integration of renewable power in a cost-efficient way. The OptGRID project (and tool developed) will demonstrate the benefits of using Dynamic Line Rating (DLR) techniques namely in terms of: 1) increasing the levels of renewable penetration (avoided curtailment) in the power system and 2) reducing the number of market splitting hours in the Electricity Market and consequent impact on electricity market prices. The goals of the project will be achieved through the application of its tools to different case studies bearing in mind current and future scenarios of high renewable power penetration levels in the power system, as well as different constraints occurring in the operation of the Electricity Market, which may cause the activation of market splitting mechanism.

Workprogram

Workflow of the project’s methodology.

The Dynamic Line Rating Process: the DLR analysis will be used to assess the actual capacity (ampacity) for the lines near congestion. Since the cable temperature is a preeminent factor in computing the power line’s ampacity, its thermal behavior assessment leads to a quasi-stationary approach modeled as an iterative process with a time step of one hour over the day-ahead energy market time horizon. For each iteration step, the power flow values from an OPF (Optimal Power Flow), without DLR, are to be used to obtain the actual values flowing in each one of the near congested power lines. Those current values are then used to compute the cables resistance used on the thermal equilibrium balance to assess the hourly “real” ampacity values of the power line.

WP1 Coordination and management

The present WP is dedicated to the project management and coordination, including the elaboration of an exploitation plan for the project results.

WP2 Meteorological, network and market data

This WP deals with the necessary data to conduct OptiGRID research activities. It will make use of:

· Meteorological data: hourly forecast meteorological data with a time horizon comprising the day-ahead market;
· Transmission network data: transmission network technical and geographical information;
· Electricity market data: Electricity prices, market splitting activation market related to market operation.

The data from this task will feed the DLR and the optimal power flow (OPF) modules, developed within the project, for application to each case study.

WP3 Development of models for active, high efficiency electric network operation
In this WP, three major objectives are to be achieved:

·
Develop, adapt and incorporate mathematical models, for networks with high levels of variable renewable generation (VRE), to the study of the constraints arising at national transmission grid (RNT) operation, from both the high penetration level of renewable energy and the impositions ensuing from the energy market operation thus allowing to quantify the benefits resulting from including the DLR analysis.

·
Build a DLR analysis software, which will incorporate the developed models under a structured operational methodology, to allow automated DLR analysis in large-scale power networks with high levels of distributed VRE.

· Develop a Geographic Information System (GIS) interface, as a user-friendly interaction platform, to aggregate a set of procedures suitable to perform the diverse analysis defined in the present project and guide the user through the different steps in each procedure.

WP4 Development of RES Case Studies
In this task three case-studies will be defined:

·
A region with large distributed wind capacity;
· A region with large PV production
· Market splitting occurrence in MIBEL due to congestion in interconnections.

Given the fact that 20% of the overhead power lines in the RNT are exploited near their thermal limits, and the operational gains granted by using DLR, an analysis of the utilization rate of the lines in the region of case studies is proposed to identify potentially congested lines.

WP5 Implementation of models. Analysis of results
This task will use the models and tools developed in the scope of OptiGRID. It will apply them to the three different case studies built within WP 4. The impact of applying the DLR analysis tool to real case studies will be demonstrated and analyzed.

WP6 Dissemination and valorization of OptiGRID results
The dissemination and valorization activities developed in this task are planned to communicate project activities and outcomes to a wide audience, which includes industry, academia, policymakers, and the general public. In this WP a dissemination plan will be developed and implemented.

Team

LNEG  
Ana Estanqueiro (Coordinator)
Teresa Simões
António Couto
Joaquim Duque
Hugo Algarvio

R&D NESTER
Rui Pestana (Co-Coordinator)
Nuno Souza e Silva
João Esteves
Cao Yang
Isabel Alvite

Documents and Events

To be announced.

Contacts

LNEG - Laboratório Nacional de Energia e Geologia
Estrada da Portela, Bairro do Zambujal
Apartado 7586 – Alfragide
2610-999 Amadora
PORTUGAL

Monday - Friday
9h00 > 12h30 - 14h00 > 17h30

Project Coordinator
Ana Estanqueiro
Tel. (+351) 21 092 46 00
Email: ana.estanqueiro@lneg.pt

Co-Coordinator
Rui Pestana
Tel. (+351) 21 001 13 00
Email: rui.pestana@rdnester.pt

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