Electricity Generation Facility Connection Requirements
Generating Facilities and Public Distribution Systems
Definitions
Generating Facilities: Designed to transform any type of energy into electrical energy.
Public Distribution System: Electricity networks owned or operated by entities whose primary purpose is the distribution of electricity for sale.
Self-Generating Company: Produces electricity, individually or jointly, for all or part of its own needs.
General Conditions
Generating facilities, including fuel tanks and pipes, must comply with specific regulations and directives.
Generating facilities housed in buildings or industrial premises must comply with fire protection regulations.
Premises with internal combustion engines must be properly ventilated.
Exhaust ducts for combustion gases and combustible material must be directed outside or through an energy recovery system.
Connection Conditions
4.1. Isolated Generating Facilities
Connection to receptors on premises without connection to the public network or other generators requires a device for connecting and disconnecting the load on the generator output circuit.
Multiple generators requiring synchronization must have manual or automatic equipment for this operation.
Portable generators should incorporate general overcurrent protection and necessary direct and indirect contacts.
4.2. Assisted Generating Facilities
Indoor replacement feeding may be at various points with a switching system for all active and neutral conductors.
Cargo transfer maneuvers without cutting the connection to the Public Distribution Network must meet these requirements:
- Charge transfer without cutting generators exceeding 100 kVA
- Disconnect the generator neutral ground during interconnection with the public network
- Install the switching system with the public distribution network’s measuring apparatus, accessible to the distributor
- Include a protection system to prevent sending power to the grid generator
- Include protection systems for voltage, frequency, overload, short circuit, and out-of-sync conditions
- Have a synchronization team with a maximum interconnection time of 5 seconds
The auxiliary contact switch will connect to a neutral ground for load transfer without cutting.
Protective elements and switch connections must be sealed or guaranteed against parameter changes, with permanent distributor access.
4.3. Interconnected Generating Facilities
Maximum power for interconnected plants depends on the network’s characteristics: voltage, short circuit power, line capacity, etc.
4.3.1. Maximum Power for Low Voltage Interconnection
Interconnection to 3×400/230 V networks is generally admissible if the total generator power does not exceed 100 kVA or half the processing line capacity.
For 3×220/127 V networks, the limit is 60 kVA or half the processing line capacity. The facility should be prepared for future 3×400/230 V operation.
For wind generators, to avoid fluctuations, power should not exceed 5% of the short circuit power at the connection point.
4.3.2. Starting and Meshing Conditions
4.3.2.1. Asynchronous Generators
The connection CDT should not exceed 3% of the rated voltage.
For wind generators, connections should not exceed 3 per minute, with a voltage drop limit of 2% for 1 second.
Suitable arrangements will limit connection intensity and voltage drops.
Connect induction generators only at 90-100% of synchronous speed.
4.3.2.2. Synchronous Generators
Use of synchronous generators requires agreement with the distributor, based on independent operation needs.
The plant will have automatic or manual synchronization equipment, unless asynchronous connection is possible.
Connection should occur when timing differences do not exceed: ±8% voltage difference, ±0.1 Hz frequency difference, ±10° phase difference.
Interlocks will prevent paralleling where synchronization equipment is absent.
4.3.3. Maneuver and Measurement Equipment
Install a circuit breaker with protections in the internal installation source to prevent internal faults from affecting the connected networks.
Protections and wiring must be sealed, with the switching device accessible to the self-generator.
The link switch will have an auxiliary contact to ground the generation neutral during independent operation.
A recording device will measure energy supplied by the self-generator.
Asynchronous generators will have a reactive power counter.
4.3.4. Reactive Power Control
Asynchronous generator facilities should have a power factor of at least 0.86 at nominal power, with capacitors if necessary.
Safety devices should ensure shutdown within 1 second of a Public Distribution Network interruption.
The distributor may waive power factor compensation if it can provide reactive power.
Synchronous generators should maintain a power factor between 0.8 and 1, with excitation control for regulation.
5. Connection Cables
Cables should be designed for at least 125% of the maximum generator intensity, with a voltage drop not exceeding 1.5% at rated current.
6. Wave Form
Generated voltage should be nearly sinusoidal, with maximum harmonic rates of: 4/n for even order, 5 for 3rd order, and 25/n for odd order ≥ 5.
Harmonic rate is the percentage ratio between the effective value of the harmonic and the fundamental.
7. Protections
The prime mover and generator will have manufacturer-recommended protections.
Generator output circuits must have protections as per applicable ITC regulations.
Interconnected facilities will have protections acting on the interconnection switch, verified and sealed by a recognized laboratory.
Minimum protections include overcurrent, instantaneous undervoltage (acting within 0.5 seconds at 85% voltage), surge protection (acting within 0.5 seconds at 110% voltage), and maximum/minimum frequency protection (acting after 5 occurrences outside 49-51 Hz).
8. Ground Facilities
8.1. General
Grounding systems must ensure that voltages on metal frames do not exceed limits defined in MIE-RAT 13.
Grounding systems should prevent fault transfers to public or private networks.
8.2. Grounding Based on Operation
8.2.1. Isolated Generating Facilities
The grounding network must be independent of other systems, with a maximum voltage difference of 50 V during fault conditions.
If the generator has no neutral, a star-connected phase transformer can be used for grounding.
Parallel generators must be grounded at a single point, the neutral connection.
8.2.2. Assisted Generating Facilities
With a grounded neutral RDP, the grounding scheme will be TT, with masses and receivers connected to a neutral independent of the Public Distribution Network.
With specific permission, the same ground can be used for the neutral and masses if a separate ground is impossible.
An auxiliary pole in the interconnect switch will ground the generation neutral during independent operation with uncut load transfer.
8.2.3. Interconnected Generating Facilities
With a grounded neutral RDP, the grounding scheme will be TT, with masses and receivers connected to a neutral separate from the Public Distribution Network.
Without RDP connection, an auxiliary pole in the interconnection breaker will disconnect the RDP neutral and ground the generation neutral.
A detection device will shut down the plant if the neutral current exceeds 50% of the rated value.
8.3. Wind Generators
The protective earthing for the tower and equipment is independent of the installation’s other grounding.
9. Start-Up
Before commissioning, submit a project to the distributor for approval of interconnection facilities and elements affecting supply safety. The distributor will verify compliance with regulations.
This procedure is not required for isolated generating facilities.
10. Other Provisions
All connection-related actions must comply with established legislation.
The distributor may disconnect the facility in case of immediate risk, notifying the competent authority.