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4.2.1 ›

RNT OPERATION

USE OF TRANSMISSION SYSTEM 

In 2016, energy transmitted by the National Transmission System (RNT) saw a significant increase of 8.6% over the previous year, standing at the highest ever figure of 46.7 TWh. This figure exceeds the previous annual maximum of 2005 by 4.8%. Maximum power transmitted stood at 9,140 MW, equalling the highest ever value recorded for the RNT. This peak is around 700 MW above the maximum recorded last year, and around 300 MW higher than the previous maximum high registered in 2007.

Despite the slowdown seen in recent years, and the increase in injection from small-scale producers with regard to the distribution network, the Iberian market saw strong exports throughout the year, leading to the highest values ever in terms of power transmitted by the RNT

Network losses, which stood at 801 GWh, increased from 1.56% to 1.72% of transmitted energy. In addition to more intensive use of the network, this increase is largely related to the considerable increase in the production of renewable energies, with greater concentration in the north of Portugal.

46,7 TWh

ELECTRICITY ENERGY TRANSMITTED
BY THE NATIONAL TRANSMISSION SYSTEM
TWh
  '16 '15
ENERGY INTAKE INTO THE NETWORK
46,7
43,0

   Power plants

39,6

33,0

   Interconnections

4,6

8,1

   Distribution Network

2,5

1,9

ENERGY OUTPUT BY THE NETWORK
45,9 42,3

   Power plants / Direct customers

3,3

3,3

   Interconnections

9,7

5,8

   Distribution network

32,9

33,2

   Own consumption

0,0

0,0

LOSSES
0,8
0,7

The interconnection capacities offered to the market stood at 1,950 MW for import and 2,400 MW for export. With the national system exporting significantly throughout year, congestion in the Portugal-Spain direction was seen in 7% of periods, while in the Spain-Portugal direction, interconnection saw congestion in only 1% of periods. 

QUALITY OF SERVICE

The quality of technical service provided - understood as being security and continuity of supply of electrical power with the necessary technical characteristics - achieved suitable levels. The trend observed in previous years towards a gradual
and sustained improvement in the performance of the National Transmission System (RNT) was consolidated.

With regard to continuity of service, the six general indicators set out in the Quality of Service Regulations (ENS, EIT, SAIFI, SAIDI, SARI and MAIFI) recorded good positive values. It can thus be seen that the policies and strategies implemented by the RNT concessionaire for electrical power transmission are both suitable and efficient in network operation (attributes which are confirmed by comparative analysis studies of technical-economic performance among electricity TSOs).

The Equivalent Interruption Time (EIT), an indicator of overall performance commonly used by electrical utility firms, was 20.4 seconds. This is the value directly attributable to REN, and corresponds to energy not supplied of 31.8 MWh.This figure represents what would be a practically uninterrupted supply of electrical power (at 99.99994% of the time, i.e. 999 hours, 59 minutes and 58 seconds in every 1,000 hours) to a single “equivalent” consumer, for the entire country, with power and energy which would represent all the different delivery points to the national distribution network and consumers directly connected to the RNT.

EVOLUTION OF EQUIVALENT INTERRUPTION TIME - EIT

In 2016, the monitoring of voltage waveform quality continued at delivery and interconnection points on the RNT.

The measurements carried out continued to show results that, with a limited number of exceptions in individual and localized cases, match the figures recommended in the quality of service regulations.

The overall level of the electrical energy quality depends on the number of incidents recorded or which impact on the transmission grid. In 2016, there were 183 incidents and interruptions (35% more than in 2015), 160 of which originated in the Extra High Voltage Network (EHV), 11 in the High Voltage Network (HV) and 12 in other networks but impacting on the REN EHV and HV networks. Only six incidents (3% of the total) actually caused interruptions to the supply of electricity to customers, having caused six interruptions at delivery points.

EVOLUTION IN THE NUMBER OF INCIDENTS

NETWORK BEHAVIOUR 

During 2016, the major congestions that occurred in the RNT were associated with grid element outages, which were solved through the generation of network constraints and the introduction of topological changes to the network. In this regard, of particular note were outages which occurred due to the capacity increase in 150 and 400 kV lines in the Portuguese central interior which required special topological measures. These measures sought to minimize restrictions on power generation and maximize the commercial capacity of the interconnection with Spain. Moreover, outages also occurred due to the remodelling of protection, automation and control systems at the Torrão and Évora substations which required special topological measures. These measures sought to minimize restrictions on power generation and maximize supply security for consumption.

In 2016, despite the slight rise in the consumption of electricity in mainland Portugal, the number of RNT lines which had to be shut down as a last-resort solution to control voltage fell substantially. This reduction was mainly due to greater availability of means to manage relative energy with the entry into service of new equipment, shunt reactances, in line with development and investment plans for the transmission system.

SYSTEM OPERATION 

For the first time ever, in 2016 the Portuguese electricity system had a positive annual export balance of 5 TWh. Several maximum historic figures were achieved:

    • Combined cycle production: Power = 3 344 MW;
    • Large hydro production: Power = 5,547 MW; Energy = 114.6 GWh;
    • Wind production: Power = 4,453 MW;
    • Photovoltaic production: Power = 390 MW; Energy = 3.5 GWh;
    • Pumped storage hydroelectric: Power = 1933 MW; Energy = 18.9 GWh;
    • Exports: Power = 3,529 MW.

In conclusion, the growth in renewable energy production and market operation led to several maximums in the use of the transmission network, although consumption itself did not change significantly.

 

 

MARKET OPERATION 

In 2016, seven new market agents started and one market agent closed in the National Electricity System (SEN). At the end of the year, there were 39 market agents, three of which are producers. 

In August 2016, REN joined the IGCC project (International Grid Control Cooperation). The IGCC is a key project to implement the Imbalance Netting process. This process seeks to improve cooperation between TSOs (Transmission System Operators) for real-time offsetting of imbalances among the different electricity systems involved. The aim is to reduce the mobilization of secondary regulation power, thus helping improve the efficiency of the services required to operate the SEN with suitable levels of supply security. 

At the end of 2016, REN started initial testing on connectivity between the REN IT platform and the XBID platform (Cross-Border Intraday Initiative). The XBID platform is managed by DBAG (Deutsche Börse AG) and seeks to ensure the interaction of the IT platforms of project members so as to create an integrated intraday market throughout Europe. When XBID starts operation, orders made by market participants can be continuously met in any other participating country the project, provided that interconnection capacity is available.

Of note in terms of international developments:

    • In July 2016, as part of the Market Regional Coupling project, coupling was successfully started on the Austria-Slovenia border. 
    • On 27 September, Regulation (EU) No 2016/1719, which provides guidelines on forward capacity allocation, was published.
    • On 17 November 2016, the Agency for the Cooperation of the Energy Regulators (ACER) communicated its decision for the determination of the capacity calculation regions.

PERFORMANCE OF TRANSMISSION SYSTEM ASSETS

    • Availability

The combined availability rate, a regulatory indicator introduced by ERSE in 2009, stood at 98.33% in 2016, a similar figure to that for 2015. The following graph shows the annual evolution of this indicator over the last five years. This performance represents a positive evolution in terms of coordination and planning of grid outages during the period in question. 

COMBINED AVAILABILITY RATE

    • Reliability

In 2016, RNT lines performed satisfactorily, despite an increase in the number of incidents over figures for the previous year (+85%). This was essentially due to the high number of forest fires seen in the summer months. The graph below illustrates the performance of lines in the last five years, with regard to the number of faults per 100 kilometres of circuit.

EVOLUTION IN THE NUMBER OF FAULTS ORIGINATING IN RNT LINES PER 100 KM OF CIRCUIT

The overall availability rate for line circuits, including terminal panels, was 98.62%, a figure which was slightly lower than that for the previous year (-0.05%).

In general, sub-stations performed favourably. In spite of this, there was a slight increase in the number of breakdowns in transformers and circuit breakers compared with the 2015 figures, although, in the majority of cases, not impacting on network operation. The overall availability rate for transformers and auto-transformers (including the respective panels) stood at 97.45%, a figure slightly lower than that seen in 2015 (-0.31%). This indicator is affected mainly by remodelling and replacement work on HV equipment and transformers.

More in-depth technical detail is available in the Quality of Service Report published annually by REN.