Transmission Grid Operator

The OHTL division is responsible for the effectiveness of the transmission grid of Macedonia. The task of this division is to maintain a 2300 km transmission grid operated by AD MEPSO. To fulfil these duties, the division is structured into two units and one section, each comprised of well-trained experts dedicated to the meticulous maintenance of the transmission grid.

 

The OHTL Division includes: 

 

• OHTL Maintenance Unit

 

The duties of this section include:

- Projects financed by EIB, EBRD, World Bank and AD MEPSO’s participation;

- Providing title deeds and preparation of documentation for facility use permit;  

- Tender documentation preparation and evaluation of offers; 

- Participation in project committees, revision of urban project documentation, et cetera.  

 

• OHTL Maintenance Unit include: 

 

- Transmission line crew Skopje  

- Transmission line crew Bitola

- Transmission line crew Shtip

- Transmission line crew Ohrid

- Measurement Section.

 

This Unit is responsible for the reliability of the transmission lines as part of the power system. Their work activities comprise regular inspection and revision of the OHTLs, repairs and putting into operation the determined malfunctions during routine inspection. 

The crews for maintenance of the transmission line infrastructure have trained members capable of repairing any defect at the fastest pace, regardless of what caused it in the first place. The inspection of the transmission lines is done two times a year, in spring and autumn, followed by proper revisions.  

 

• OHTL Corridors Maintenance Unit lists:
•  

- Crew - Skopje,

- Crew – Bitola 

- Crew – Shtip

- Construction Maintenance Section – Ohrid. 

 

The Unit has an obligation to preserve the OHTLs clearances, removing the trees and vegetation that grow within the safety zone of the lines to keep the clearances clean, thus preventing eventual outages and defects on the transmission lines in advance. 

Moreover, the OHTL Corridors Maintenance Unit cleans the overgrown and overfilled tower foundations and maintains the access roads toward the towers. 

The fundamental operational data required by the Unit is derived from periodic reports submitted by the OHTL crews following their inspections.

The Relay Protection Division has the following units:

• Relay Protection Testing Unit;
• Relay Protection Analyses and Calculations Unit;
• Relay Protection Equipment Maintenance Unit.

 

The Division of Relay Protection and Secondary Circuits is in charge of the accuracy and functionality of the relay protection in the power transmission system. Each component of the transmission system: transmission line, power transformer, busbars, energy cable and other equipment must be protected with suitable protection.

 

This Division's foremost objective is to ensure accurate and selective working of the relay protection for the safety of the people and the connected equipment to the power system of the Republic of North Macedonia, simultaneously enabling high-quality and reliable power supply to all consumers. To achieve this, the Division conducts relay protection annual testing, intervening or replacing units as necessary to maintain optimal functionality. Tests are carried out by AD MEPSO's experts who hold essential certifications and have undergone training at globally recognized manufacturers of relay protection and testing equipment. They operate the most sophisticated equipment and software crucial for all required calculations and inspection of the selectivity of the relay protection. In the event of an outage in the power system, the Division actively participates in the making of the outage analysis and proposes solutions. The Division for Relay Protection and Secondary Circuits actively contributes to the construction of new facilities within the electricity transmission system.

The Revitalization Division is part of the subsidiary Transmission Grid Operator (TGO), and its core function is the renewal of the energy facilities of TGO. 

The Revitalization Division includes: 

• Electrical Installation Works Unit;

This Unit covers the electrical installation works like the replacement of circuit-breakers, disconnectors, signalization and control.  

• Project Documentation Unit;

They design construction drawings for detailed designs and as-built designs for circuit-breakers and disconnectors.

• Section for preparation of the construction site within substations;

This Section of the Revitalization Division carries out civil works for the replacement of high-voltage equipment, repair of oil pits, roofs, string fences, concrete gantries and conduits, sanitary facilities within SSs, technical maintenance of the AD MEPSO administrative building and substations.

The transmission grid, which is under MEPSO’s management and maintenance, integrates more than 50 substations across the country. MEPSO owns 14, while the rest of the substations are in joint ownership with the DSO companies.

The Technical Control and the Substation Division are responsible for the maintenance, modernization and upgrade of the equipment. 

The Department for Technical Control, Maintenance and Testing of Substations divides its activities into the following units:

• Maintenance of Substations Unit

This Unit is held responsible for duly and prompt maintenance of the high-voltage equipment within the substations, undertaking planned or unplanned activities. The planned activities include inspections, revisions, repairs and replacement of HV equipment. These activities are conducted on the following basis:

- Prepared plans for procurement of the required equipment, parts, tools, materials and others;

- Prepared plans for current maintenance;

- Prepared reports for completed activities.

The unplanned activities are interventions undertaken to remove defaults and defects during equipment exploitation. 

• Insulation Materials Unit 

This Unit examines the transformer oil and tests the SF6 circuit-breakers and GHA of metering transformers.

• Testing Unit 

The Testing Unit carries out various tests based on which monitors and evaluates the condition of the installed equipment within the SS.  

- Testing and estimation of the condition of the power and instrument transformers; 

 - Testing of circuit-breakers;

 - Testing of earthing installations in SS;

 - Testing of touch and step voltage in SS; 

 - Testing loop impedance;          

 - Thermovizion testing in SS;

 - Testing of ACCU batteries. 

• AC/DC Systems And Secondary Circuits Unit 

Periodical inspections/controls of the AC/DC systems; 

Inspections and starting of diesel generators; 

Periodical inspections/servicing of diesel generators. 

The Substation Division is organized in the following units: 

• Unit for operational and technical works that include: 

- construction crew,

- a crew for operational and technical works Ohrid.

• The Exploitation Unit includes:

     - Regional center „Skopje“

     - Regional center „Radovish“

     - Regional center „Bitola“

     - Regional center „Shtip“

     - Regional center „Tetovo“

     - Regional center „Ohrid“

In the facilities that AD MEPSO shares with EVN Macedonia, ESM, TE - TO Skopje and other consumers, and in coordination with the National Control Center and Control Center of EVN and ESM, the Division carries out manipulations with the aim of prompt and uninterrupted electricity supply to consumers.

All required manipulations are executed seamlessly, incorporating comprehensive safety measures for the substation reconstruction. The SS Division's employees, in collaboration with Regional Center heads, conduct routine maintenance on the secondary equipment in transformer stations (control, signalling, measurement, and AC/DC supply systems) within all substations.

- Routine daily visual inspection of the equipment; 

- Equipment testing following the monthly plan; 

- Detecting and repairing minor equipment defects. 

The construction crew is responsible for horticultural upkeep across all facilities, conducting routine maintenance on the entire water supply network, and overseeing the maintenance of all hydrant networks within our facilities.