The Power Transmission Grid
The National Power Grid Company Transelectrica SA is transmitting the electricity by means of the power transmission grid (PTG), consisting of electric substations and lines. The PTG is the electricity network of national and strategic interest, with nominal voltage higher than 110 kV.
The amount of installations managed by Transelectrica SA consists of:
81 electric substations, of which:
- One 750 kV substations
- 38 substations at 400 kV
- 42 substations at 220 kV
8834.4 km overhead electric lines (OHL), of which:
- 3.1 km at 750 kV
- 4915.2 km at 400 kV
- 3875.6 km at 220 kV
- 40.4 km at 110 kV
of which interconnection lines: 486.2 km
216 main transformer units amounting to 38058 MVA, as follows:
- 2 x 1250 MVA
- 2 x 500 MVA
- 22 x 400 MVA
- 31 x 250 MVA
- 81 x 200 MVA
- 1 x 100 MVA
- 2 x 63 MVA
- 9 x 40 MVA
- 24 x 25 MVA
- 1 x 20 MVA
- 32 x 16 MVA
- 9 x 10 MVA
The National Power Grid Company Transelectrica SA is carrying on a rigorous maintenance programme in order to keep the PTG installations in good technical conditions, as well as to observe the conditions of service quality required by the Technical Code of the PTG, the provisions of the performance standard for transmission and system services and those of the transmission and system operator licence granted to the Company. The maintenance programme aims at increased operational safety of the PTG in view of avoiding circumstances that might lead to unwanted incidents both for electricity networks and for the population or the environment.
Maintenance activities are in line with Transelectrica's concept of asset management and, according to international practice; they are a component part of asset management.
The new approach to maintenance activities has required establishing clear-cut principles under a complex strategy leading to fulfilled strategic objectives for such activities, as a support in achieving the Company's goals.
Maintenance activities are determined while taking also into account the investment plans (refurbishment, upgrading, and development) and being correlated to them, both at substation and at electric line levels. The maintenance programmes developed within the PTG included major maintenance work under project type ‘master plan' that consider the substation or the OHL in its whole, taking into account work carried out actually to all functional assemblies that simultaneously provide, through the investment component, the development, modernisation or the refurbishment and preparation of substations for remote control.
Given the extremely fast technological development and the lifetime of most equipment that exceeded 30 years, upgrading and refurbishment components have been included that provide functionality at the level of present-day technique, by replacing the outdated or worn out elements and adding certain additional ones (facilities), while also including new technologies.
The rehabilitation work (major maintenance with upgrading / refurbishment component) that was initiated and carried out at sustained pace in the last year provided as a common element proper technical solutions being adopted for the safe operation of installations.
The remote control and supervision system for transformer electric substations implemented within the National Power Grid Company Transelectrica SA is one of the Company's priorities that will lead to increased efficiency and quality of electricity transmission services, reduced number of accidental events as well as lowered operational and maintenance costs. To implement the remote control of electric installations, several important stages have been completed to elaborate the documentation required in view of achieving the organisational and functional structure, procuring the equipment and services to constitute the Remote control and supervision centres (CTS) within each transmission branch, the CTS Timisoara and CTS Sibiu being already functional; as well as elaborating programmes to apply remote control to all electric substations in the following years. All specific aspects will be stipulated in the remote control and supervision policity for the PTG installations.
Maintenance services / work are carried out within the PTG, as the case may be:
- corrective maintenance - when the defect has been detected, and it includes all actions meant to restore an installation into the condition allowing it to operate as planned;
- preventive - prophylactic maintenance to prevent defects, respectively to reduce the failure or degradation probability, the aim being to obtain a proper balance between such activities depending on the impact of various functional assemblies over the PTG goals- operational safety, availability, and efficiency;
Under the current circumstances of electricity generation and consumption within the Romanian Power System (RPS), taking into account the technologies used or legislation, ownership etc. aspects, the intention is to promote new solutions both for development and for PTG development purposes (type and size of OHL conductors; multi-circuit lines to use the existing paths; live work techniques (LW); online treatment of the insulation to transformer units, with a view to reduce the outage periods and avoid congestion costs and losses etc.).
Since the need was pointed out for a single and transparent flow of data and information with respect to maintenance activities, which would provide all the available data and control facilities for their quality, a specific database was created for maintenance activities and an IT system was devised to manage, optimise and coordinate all such activities.
The prospective maintenance programme is determined using multi-criteria analyses (technical condition; operational age; importance; remote control prospect etc.) whereby the major maintenance activities are directed mainly to the electricity transmission installations that make:
- the interconnection with neighbouring power systems;
- the connection between system regions or between important electric substations;
- the discharge of power from great producers;
- the supply of important consumption areas;
Priority work is carried out to avoid emergency situations brought about by floods, land slides vandalism acts etc.
A few achievements from the 2005 - 2010 major maintenance programme are given further
Maintenance programme to the OHL
Capital repairs to the 220 kV OHL Gutinas – Dumbrava
Capital repairs to the 400 kV OHL Porţile de Fier – Urechesti
Capital repairs to the 220 kV OHL Alba Iulia – Sugag – Galceag
Capital repairs to the 220 kV OHL Alba iulia – Cluj Floresti
Capital repairs to the 220 kV OHL Resita Timisoara
Capital repairs to the 220 kV OHL Brazi Vest – Fundeni
Capital repairs to the 220 kV OHL Fantanele – Gheorghieni
Capital repairs to the 400 kV OHL Portile de Fier – Slatina
Capital repairs to the 220 kV OHL Gutinas – FAI – Munteni
Capital repairs to the 220 kV OHL Mintia – Alba Iulia
Capital repairs to the 220 kV OHL Brazi Vest – Targoviste
Capital repairs to the 220 kV OHL Ghizdaru – Turnu Magurele
Capital repairs to the 220 kV OHL FAI - Suceava
Capital repairs to the 400 kV OHL Gutinas – Bacau Sud
Capital repairs to the 400 kV OHL Bucuresti Sud – Slatina
Capital repairs to the 400 kV OHL Isaccea – Smardan c1+c2
Capital repairs to the 400 kV OHL Tantareni – Sibiu
Capital repairs to the 220 kV OHL Resita – Iaz
Capital repairs to the 220 kV OHL Urechesti – Sardanesti;
Capital repairs to the 220 kV OHL Sardanesti – Craiova Nord;
Consolidation to the 220 kV OHL Bradu – Targoviste – milestone 87;
Capital repairs to the 220 kV OHL Pestis – Mintia;
Capital repairs to the OHL connection to the electric substation Mintia;
220 kV OHL Bucuresti Sud – Ghizdaru;
220 kV OHL Iernut – Baia Mare 3;
220 kV OHL Lotru – Sibiu Sud 1+2;
220 kV OHL Gutinas – Focsani;
400 kV OHL Mintia – Sibiu;
400 kV OHL Gutinas – Brasov
Major maintenance projects to OHLs that begin in 2011 and will be completed by 2014: the 400 kV OHL NPP – Pelicanu; the 400 kV OHL NPP - Gura Ialomitei, 2nd circuit; the 400 kV OHL Rosiori – Gadalin; the 220 kV OHL Portile de Fier – Cetate – Calafat; the 400 kV OHL Constanta Nord - Tariverde / Tariverde- Tulcea Vest etc.
Mention should be made that each year a great amount of urgent work has been executed to the OHL because the towers were endangered, as well as maintenance work to the corridor.
Maintenance programme to electric substations
- COMPLETED major maintenance projects with upgrading component (Master plan)
The 220/110 kV substation Pitesti Sud - 2005
The 110 kV substation Baia Mare 3 - 2006
The 220/110 kV substation Targoviste -2007
The 220/110 kV substation Salaj - 2007
The 220/110 kV substation Cluj Floresti -2008
The 220 kV substation Stuparei -2009
The 220/110 kV substation Turnu Magurele - 2010
The 220/110 kV substation Pestis - 2010
The 220 kV substation Baia Mare 3 - 2010
The 220/110 kV substation Gheorgheni - 2010
- Major maintenance projects with upgrading component IN PROGRESS (Master plan)
The 220/110 kV substation FAI – completion in 2011
- Major maintenance projects that begin in 2011 and will be completed by 2014: substations Aref, Hasdat, Cluj Est, and Isaccea