Procedure & Timelines for Submission of CON-4 Data and Documents for Grid Connectivity
A structured guide to the 9-step CON-4 submission process for ISTS grid connectivity under CERC Regulations and CEA Technical Standards
Grid connectivity is one of the most critical stages in any renewable energy project.
A delay in documentation, model validation, or compliance submission can directly impact project commissioning timelines.
The CON-4 submission process defined under CERC Connectivity Regulations and CEA Technical Standards creates a structured path for generators to achieve physical interconnection with the ISTS grid.
This process involves multiple stages including scrutiny by CTU and POSOCO, compliance verification, connection agreement signing, model validation, and final grid access approval.
The flow chart highlights the complete sequence and timelines involved in achieving connectivity approval.
The process starts with submission of additional details for grid interconnection in the prescribed CON-4 format.
The submission must comply with:
At this stage, developers are expected to provide:
- Technical plant details
- Single line diagrams
- Protection philosophy
- PPC and controller details
- PSCAD and PSS/E models
- Compliance study reports
- Dynamic and fault analysis data
Any mismatch or incomplete data during this stage usually creates major delays later in the process.
After submission, CTU and POSOCO review the documents and technical models.
The scrutiny mainly focuses on:
- Compliance with grid code requirements
- Model behaviour during fault conditions
- Reactive power capability
- Frequency response
- Protection coordination
- Voltage ride-through capability
During this stage, two outcomes are possible:
No Revision Required
If the submitted documents are acceptable, the process moves to the next stage.
Revision Required
If observations are raised by CTU, the application is returned to the connectivity grantee for revision and re-submission.
This is one of the most sensitive phases because repeated observations can impact overall project schedules.
Once the observations are resolved, CTU issues:
- Connection Offer (CON-5)
- Intimation for connection details
This confirms that the project is technically acceptable for further processing.
After receiving CON-5, the developer signs:
- Connection Agreement (CON-6)
- Supplementary Connectivity Agreement if required
This agreement formally establishes the connectivity framework between the developer and transmission utility.
At this stage, CTU verifies whether any variation exists compared to previously submitted connection details.
Case 1: No Variations
- Developer submits an undertaking confirming no changes from earlier submitted models
- Process moves directly toward registration and grid access approval
Case 2: Variations Identified
- Revised data and models must be re-submitted
- Compliance with CEA Technical Standards must be demonstrated again
- CTU and POSOCO perform another scrutiny cycle
- Revised CON-5 is issued
- Supplementary CON-6 agreement is signed
Many renewable projects face delays here due to:
- PPC tuning mismatch
- Incorrect dynamic model behaviour
- Plant controller instability
- Reactive power non-compliance
- Incomplete protection coordination details
Once the connectivity agreement process is completed, the renewable energy plant submits a registration request.
This request is reviewed by RLDC.
After registration approval, the developer submits a request to POSOCO for:
- First time charging
- Commencement of grid access
This request is based on confirmation that all compliances under original or revised CON-5 conditions are fulfilled.
After receiving approval, the project proceeds with physical interconnection to the ISTS grid.
This marks a major milestone for project commissioning.
The final step involves submission of:
- Final validated PSCAD model
- Final validated PSS/E model
These validated models are submitted to:
- POSOCO
- CTU
The final validated model becomes the reference model for future grid studies and operational assessments.
Key Challenges Faced by Developers
Most delays in the CON-4 process happen because of:
A well-prepared submission package can significantly reduce review cycles and approval timelines.
Why the CON-4 Process Matters
The CON-4 process is not only a documentation requirement. It ensures that renewable energy plants:
- Operate safely with the national grid
- Support grid stability during disturbances
- Meet voltage and frequency performance requirements
- Respond correctly during faults and transient events
