STU approval & intra-state connectivity
Bay availability, not plant construction, is usually the binding constraint on when a project can be energised.
Approvals · In short
STU approval is the State Transmission Utility’s sanction for connecting a generator or a bulk consumer to the intra-state transmission system. In Odisha the STU is OPTCL — Odisha Power Transmission Corporation Limited — and scheduling concurrence comes from the State Load Despatch Centre it operates. The approval covers the connectivity application, the interconnection point and bay allocation, the interconnection scheme and protection coordination, any system strengthening required, and metering compliance. Enersys Engineers prepares the technical submission and pursues the approval alongside plant construction.
What the STU assesses
- Whether the intended interconnection point can absorb the proposed injection or draw
- Available bay capacity at the receiving substation, and whether a bay extension is required
- Short-circuit level at the interconnection point after connection, and equipment adequacy
- Protection coordination between the applicant’s scheme and the utility’s upstream protection
- Any system strengthening required, and who bears its cost
- Metering, communication and telemetry compliance
The technical submission
A connectivity application is a technical document. It is assessed by engineers, and it succeeds or fails on whether the studies behind it are credible.
- Single-line diagram from the plant to the interconnection point
- Load flow and short-circuit study showing the effect of the connection
- Protection scheme with grading against the utility’s relays
- Reactive capability and grid compliance data for generators
- Metering scheme with ABT-compliant special energy meters
- Implementation programme aligned to the bay availability date
Bay extension work
Where no bay is available, one has to be built — and that work sits inside a live substation. Enersys executes bay extension as part of its EHV substation scope, which means the same organisation that obtained the approval also builds what the approval requires.
- Bay extension at the receiving substation, executed under shutdown
- Interconnection line to the substation
- Protection and metering panels manufactured to the approved scheme
- Testing, charging and commissioning with the utility
Frequently asked
What is the difference between STU and CTU approval?
The State Transmission Utility governs connectivity to the intra-state transmission system; the Central Transmission Utility governs connectivity and long-term access to the inter-state transmission system. A project connecting within one state deals with the STU — OPTCL in Odisha — while one seeking inter-state access deals with the CTU as well.
When should a connectivity application be lodged?
At DPR stage. Bay availability and any system strengthening routinely take longer than plant construction, so the connectivity route should be settled before the plant layout is frozen.
Does Enersys execute the bay extension it applies for?
Yes. Bay extension is part of our EHV substation EPC scope, including work under shutdown at a live substation.
What usually goes with this
These are the adjacent scopes clients most often need alongside it.
CTU approval & inter-state connectivity
Inter-state access is a different regime from a state connection — longer lead times, formal milestones and bank guarantees that are actually called.
Read more →ApprovalsSLDC, RLDC & NLDC registration and scheduling
Registration is a one-off. Scheduling and deviation settlement are for the life of the asset — and they carry real money.
Read more →EPCEHV substation EPC
A substation is a sequence of devices that must coordinate exactly. Get the ratings or the grading wrong and one fault takes the whole station out.
Read more →EPCTransmission line EPC
Six trades in sequence, each dependent on the one before it. This is the work behind the kilometre figure.
Read more →Need stu approval? Tell us the scope.
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