TRANSMISION SYSTEMS

With more than half-century experience in power transmission, enjoying a team of experienced engineers and experts, and employing the most modern computerized facilities, have made us able to conclude planning, designing, tendering and supervision over construction of more than seven hundred and fifty substations from 63 kV up to 400 kV Voltage.

Moreover, we have successfully completed several projects in the detailed design of switch-yards, preparation of schematic drawings of substations and complete list of materials for direct purchase of the equipments. Such activities have resulted major savings for our clients in construction of substations. The main activities of this section are as follows:

Load study, site selection and Voltage leveling, general design, preparation of technical specification and tender documents together with preliminary drawings, handling tender formalities for purchasing of material and equipment, technical and financial evaluation, choosing capable contractors and signing the Contract, comparing the design with the technical specifications, supervising the manufacturing and factory tests, preparation of tender documents related to construction, commissioning and operation, supervision over erection activities, commissioning and start of operation, attending the provisional hand over and final hand over of project and preparation of defect lists and As Built documents.

TRANSMISSION LINES ENGINEERING UNIT

Like other engineering departments in GNEC, we provide a complete range of services starting from feasibility studies to the detailed engineering design and even procurement and construction of transmission line projects. We have the most experienced group of experts and engineers in this section who have planned, designed and supervised the construction of more than 27,000 kilometers of high voltage power transmission lines. All design activities are made by taking advantage of the most advanced soft-ware packages.

A summary of our activities are as follows:

• Line route selection
• Surveying
• Selection of the types of towers
• Preparation of the loading tables & clearance diagram for different types of towers
• spotting
• Towers and Foundation design
• Conductor and shield wire design and sizing
• Insulation design and coordination
• Mechanical and electrical designs
• Preparation of technical & contractual documents
• Supervision over all stages of work
• Project management and control
• Factory and site tests
• Preparation of PAC and FAC for the
• Clients

DISTRIBUTION NETWORKS ENGINEERING UNIT

Power distribution group has performed a wide range of activities in the field of design and improvement of the distribution networks which can be very effective in reducing the electric losses and energy costs.

All design activities and system studies in this section are performed by soft-ware packages developed by this department for Ministry of Energy of Iran. This package, named MODEC, includes a data base and the following application programs:

• Load balancing
• Maintenance scheduling
• Optimum service restoration
• Fault analysis
• Load modeling
• Insulation coordination
• Optimum comprehensive planning
• Reliability studies
• Short circuit studies
• Load flow studies
• Voltage flicker control
• Optimum capacity allocation
• New customer acceptance
• Optimum lighting design

We can also plan, design and supervise the power distribution projects for urban areas and large industries.

SYSTEM STUDIES ENGINEERING UNIT

System studies group, at GNEC, established in 2003, has the main job of conducting network studies, according to the requirements of electric companies and other industrial organizations.

Outcome of the most projects consists of adding new transmission lines, substations or power plants to the system. Therefore, the new configuration of network shall be considered by performing the following studies:

• load flow studies
• short circuit studies
• transient stability analysis

For above mentioned works, some scenarios are defined and after performing the studies, the best plans will be investigated by considering economical aspects of project.

In case of need to modify network, to achieve Loss reduction and/or short circuit level reduction, it can be done by utilizing professional softwares. The softwares used in system studies group includes but is not limited to PSS/E, Dig SILENT, ETAP and Cyme.

To sum up the above, the main activities of system studies group in GNEC are:

Studies to connect power plants, substations and/or transmission lines to existing networks

Loss reduction Studies

Short circuit level reduction calculation

Placement, sizing and connection studies for DGs

Industrial plants studies and determination of weak points of the network and technical suggestions as well.

For Industrial projects, all required studies and calculations are performed in the following areas:

• Load Flow Calculations
• Short Circuit analysis
• Motor Starting
• Transient Modes
• Harmonics studies and reduction
• Protection Coordination
• Reliability Calculations