Background
The Grid Code establishes the technical, operational, and commercial framework governing the planning, operation, and maintenance of the Gujarat power grid — covering the State Transmission System (STS), generating stations, distribution systems, and all entities connected to or seeking connection with the Gujarat grid. The Grid Code is aligned with the Indian Electricity Grid Code (IEGC) issued by CERC and supplements it with State-specific requirements.
The Grid Code governs a wide spectrum of obligations — from long-term transmission planning and connection standards to real-time operational disciplines, safety protocols, outage management, data submission, event reporting, grid restoration, and commercial settlement of Unscheduled Interchange (UI) and VAr charges. It applies to all Users — including generating companies, Distribution Licensees, captive power plants, open access consumers, and the State Transmission Utility — and to the SLDC as the body responsible for day-to-day grid operations. All entities connected to the Gujarat grid are required to comply with the Grid Code, failure to do so attracting penal consequences under the Electricity Act, 2003.
Applicability
The Gujarat Grid Code applies to all Users of the Gujarat Transmission System, including generating companies (whether State, Central, or private), Distribution Licensees, Captive Power Plants (CPPs) above 5 MW connected to the grid, open access consumers, the State Transmission Utility (STU), Transmission Licensees, and the State Load Despatch Centre (SLDC). Generating companies are subject to obligations relating to planning data, scheduling, outage management, reactive power support, governor operation, AVR compliance, SCADA data transfer, unit tripping reporting, and capability declaration. Distribution Licensees are subject to demand forecasting, load shedding, power factor maintenance, reactive power compensation, UI payment, and grid restoration obligations. All users — irrespective of category — are bound by safety, metering, communication, event reporting, and data submission requirements under the Grid Code.
Compliance Requirement Under Rules in Accordance with the Sections:
Every Distribution Licensee must submit annual 10-year peak load and energy forecasts — along with the methodology and underlying assumptions — to the State Transmission Utility (STU) by 31st January each year. The forecasts must include projections for each Connection Point and Interface Point with the Transmission System.
All users shall supply to the STU the desired planning data — including load growth, generation capacity additions, and constraints in the existing system — from time to time, to enable the STU to formulate and finalise its transmission plans.
The following minimum safety working clearances shall be maintained for bare conductors or live parts in outdoor substations, excluding overhead lines of HV and EHV installations, as per CEA notification dated 20th September 2010, Clause 44(2)-(iii): 12 kV — 2.6 m; 36 kV — 2.8 m; 72.5 kV — 3.1 m; 145 kV — 3.7 m; 245 kV — 4.3 m; 420 kV — 6.4 m; 800 kV — 10.3 m.
Overhead line conductors across streets must maintain minimum heights: 5.8 m for lines up to 650 V and 6.1 m for lines above 650 V up to 33 kV. Conductors erected elsewhere than along or across any street shall maintain: not less than 4.6 m for bare lines up to 11 kV; 4.0 m for insulated lines up to 11 kV; 5.2 m for HV lines above 11 kV up to 33 kV; and 5.2 m plus 0.3 m for every additional 33,000 V (or part thereof) above 33 kV, with a minimum of 6.1 m along or across streets.
Where an overhead line of voltage exceeding 650 V passes above or adjacent to a building, it shall maintain — based on maximum sag — a vertical clearance above the highest point of the building of not less than: 3.7 m for lines up to 33 kV; and 3.7 m plus 0.3 m for every additional 33 kV (or part thereof) for lines above 33 kV. The horizontal clearance between the nearest conductor and any part of the building shall, based on maximum deflection due to wind pressure, not be less than: 1.2 m for lines above 650 V up to 11 kV; 2.0 m for lines above 11 kV up to 33 kV; and 2.0 m plus 0.3 m for every additional 33 kV (or part thereof) for lines above 33 kV.
Every user must furnish all planning data as per Annexure B to the STU. One-time data shall be submitted within 6 months of the Grid Code coming into effect. Ongoing data shall be submitted by 1st April and 1st October every year. Users must also update the STU immediately upon any addition of a generating unit or modification of the distribution system.
Open access consumers, generating companies, Distribution Licensees, and traders shall provide meters as may be specified by the Commission in the GERC (Terms and Conditions for Intra-State Open Access) Regulations, 2011.
Any user seeking a new or modified grid connection must submit an application in the standard format to the STU or Distribution Licensee and execute a Connection Agreement with them before establishing the connection, as per the GERC (Terms and Conditions for Intra-State Open Access) Regulations, 2011.
STUs and users connected to the Gujarat Grid shall provide reactive power compensation and related facilities near load points in low voltage systems to minimise reactive power exchange with the grid and maintain voltage within the specified operating range. Persons already connected to the grid shall also provide additional reactive compensation as per the quantum and time frame decided by the respective RPC in consultation with RLDC. Users and STUs shall provide information to RPC and RLDC regarding the installation and healthiness of reactive compensation equipment on a regular basis.
Reliable speech and data communication systems shall be provided for grid supervision, control, and data exchange under all conditions. Users, STUs, and CTU shall install telemetering and communication facilities for power system parameters as specified in the Connection Agreement.
Recording instruments — including Data Acquisition Systems (DAS), Disturbance Recorders, Event Loggers, Fault Locators, and time synchronisation equipment — shall be installed and maintained in working condition in the Gujarat Grid. All users and STUs shall provide and maintain these systems to record dynamic grid performance and disturbances.
The STU and concerned users shall ensure safety in compliance with the CEA Technical Standards for Grid Connectivity, GERC Intra-State Open Access Regulations, 2011, and CEA Safety Requirements for electrical installations, as amended from time to time. All utilities shall have in place a cyber security framework to identify critical cyber assets and protect them to support reliable operation of the grid.
Wind and solar plants connected at 66 kV and above must maintain voltage Total Harmonic Distortion (THD) within 5% and individual harmonics within 3%. Current THD at the connection point shall not exceed 8%. Harmonic distortion testing must be conducted every six months and the results reported to the STU and concerned licensees.
Wind generating stations connected at 66 kV and above shall provide dynamic reactive power support and maintain power factor between 0.95 lagging and 0.95 leading. Solar generating stations using inverters shall maintain power factor between 0.90 lagging and 0.90 leading for grid synchronisation. Both wind and solar generating stations shall have fault ride-through capability of not less than 300 milliseconds to ensure grid stability during disturbances.
Distribution Licensees shall prepare 5-year short-term demand forecasts based on the previous financial year, taking into account load growth, loads above 1 MW, Demand Side Management (DSM), energy conservation, distribution losses, energy sales, and peak load requirements at connection and interface points. The forecasts, along with supporting methodology, data, and assumptions, shall be submitted annually to the STU, Transmission Licensee, and GERC.
All users and Distribution Licensees must develop methodologies and mechanisms for daily, weekly, monthly, and yearly demand estimation (MW, MVAr, and MWh) for operational purposes. Based on these estimates and the estimated availability from different sources, demand management measures such as load shedding and power cuts shall be planned. All users and Distribution Licensees shall provide relevant data to SLDC from time to time. SLDC shall use these inputs to conduct system studies and assess transfer capability for facilitating intra- and inter-state open access operations.
All users and the STU shall provide all data specified in Annexure E of the Grid Code to the SLDC in the prescribed format and at the prescribed intervals.
Each generating company shall submit to the SLDC, in writing during the month of March every year, the generation planning parameters for each of its generating units for the ensuing year.
Each generating company shall submit annual generator performance charts to the SLDC from April onwards for each generating unit, including Generator Transformer details and reactive capability limits at transmission voltage up to 10% above normal, as required by SLDC.
Notwithstanding any provision in an approved outage plan, no cross-boundary circuit or generating unit of a generating company shall be removed from service without specific release from the SLDC. This restriction does not apply to individual generating units of a Captive Power Plant (CPP) operating in standalone mode. If any change in restoration is anticipated during an outage, the SLDC or the concerned user shall promptly inform the other party along with a revised estimate of restoration time.
Generating companies and Distribution Licensees shall submit their annual outage programmes — specifying the unit or sub-station, proposed start date, and duration — to the SLDC by 15th October each year. Distribution Licensees with load loss of 20 MW or less are exempt from this requirement.
Each user shall obtain final approval from the SLDC prior to availing any outage of its system or equipment connected to the Gujarat Grid.
Distribution Licensees shall submit annual demand estimates covering the period April to March by 31st January each year. They shall also provide the SLDC with details of loads that can be shed in discrete blocks, along with the related load-shedding arrangements.
In addition to the annual demand estimates, Distribution Licensees shall update their demand estimates on a month-ahead basis every month, in the format and at the intervals required by the STU or SLDC.
Distribution Licensees shall also update their demand estimates on a day-ahead basis as required by the STU or Transmission Licensee, to support daily load-generation balancing and operational planning by the SLDC.
Distribution Licensees and bulk consumers shall restrict drawl to within their schedules when grid frequency falls below 49.8 Hz and ensure zero over-drawl when frequency is at or below 49.7 Hz. They shall comply promptly with directions from SLDC or RLDC for demand disconnection, load shedding, or generation backing down during transmission congestion, and submit compliance reports to SLDC. SLDC shall develop standard communication formats for issuing such directions, and users must respond immediately. All users shall comply with RLDC/SLDC directions under the CERC (Measures to Relieve Congestion in Real Time Operation) Regulations, 2009.
All users shall cooperate with the STU or Transmission Licensee to ensure that their respective sections of the power system operate in synchronism with the Gujarat power grid at all times.
Transmission lines of 132 kV and above, and 66 kV CPP grid lines, shall not be opened without prior clearance from the SLDC except during emergencies. Similarly, SLDC approval must be obtained before restoring such lines to service. Any tripping of 132 kV and above transmission lines or 132 kV/50 MVA and above power transformers shall be promptly reported to SLDC or Sub-SLDC by the Engineer-in-charge, along with reasons, restoration time, and relevant disturbance and sequential event recorder data.
Generating companies must keep the governors of all qualifying generating units in free operation at all times, with no dead bands or time delays imposed. Any governor lockout must be immediately intimated to the SLDC along with reasons and estimated duration. All governors must have a droop setting of 3% to 6%. Generating units must be capable of picking up 5% extra load above declared Maximum Continuous Rating (MCR) for at least five minutes when frequency falls due to a system contingency.
No generating company shall suddenly increase or decrease its generation by more than 50 MW without prior intimation to the SLDC, except during emergencies or to prevent imminent danger to costly equipment. Similarly, no Distribution Licensee shall cause a sudden decrease or increase in its load — due to imposition or lifting of power cuts — without prior intimation and consent of the SLDC, particularly when frequency is above 50.5 Hz or below 49.5 Hz. When frequency falls below 49.7 Hz, partly loaded generating units shall increase load as per capability. When frequency reaches 50.2 Hz or above, no standby unit shall synchronise or increase generation without SLDC approval.
All generating units must keep Automatic Voltage Regulators (AVR) in operation with appropriate settings at all times. If the AVR is bypassed for any reason, the SLDC must be immediately intimated with the reasons and estimated duration, and SLDC concurrence must be obtained before the bypass continues.
All users must take all possible measures to maintain grid frequency within the 49.7 to 50.2 Hz band, within which steam turbines conforming to IEC specifications can safely operate. No important element of the state grid shall be deliberately opened or removed from service at any time, except when specifically instructed by SLDC or with its specific prior clearance. The list of important grid elements subject to these restrictions shall be prepared by SLDC in consultation with users, CTU, and STUs and published on the SLDC website.
Distribution Licensees shall provide the SLDC with estimates of loads that may be shed, when required, in discrete blocks, along with details of the load-shedding arrangements for each such block.
In emergency situations where an important grid element is opened or removed from service, the user must communicate this to the SLDC at the earliest opportunity. The SLDC shall further inform the RLDC regarding such opening or removal.
Thermal generating units of 200 MW and above and hydro units of 10 MW and above operating up to 100% MCR shall be capable of instantly increasing to 105% and 110% MCR respectively during sudden frequency drops. After such an increase, a unit may ramp back to the original level at approximately 1% per minute if sustained operation at the increased level is not feasible. Units not meeting this requirement shall operate (synchronised with the grid) only after obtaining SLDC permission.
Distribution Licensees and STUs shall install automatic under-frequency and df/dt relays for load shedding as per the plan finalised by the RPC, and shall ensure these schemes are always functional. The SLDC shall furnish monthly UFR/df/dt relay operation reports to the RPC and upload them on the SLDC website. The RPC shall carry out periodic inspections of under-frequency relays and shall decide the corrective actions required from Distribution Licensees and STUs to achieve the required load relief.
All users must: (a) facilitate the identification, installation, and commissioning of System Protection Schemes (SPS), including inter-tripping and run-back arrangements; (b) keep all SPS always in service; and (c) obtain prior permission from RLDC — stating the reason and estimated duration — before taking any SPS out of service.
Each user, STU, and CTU shall provide and maintain adequate and reliable communication facilities — both internally and with other users, STUs, RLDC, and SLDC — to ensure the exchange of data and information necessary to maintain reliability and security of the grid. Wherever possible, redundancy and alternate communication paths shall be maintained along important routes, such as the SLDC to RLDC link.
All users and the STU must send disturbance recorder and sequential event recorder output or data to the SLDC within 3 days of any grid disturbance or event, for the purpose of analysis. No user or STU shall block any data or information required by the SLDC for maintaining reliability and security of the grid or for event analysis.
All users, SLDC, and the STU must take all possible measures to ensure that grid voltage always remains within the operating range specified in the prevailing Indian Electricity Grid Code (IEGC): 765 kV (728–800 kV); 400 kV (380–420 kV); 220 kV (198–245 kV); 132 kV (122–145 kV); 66 kV (60–72 kV); 33 kV (30–36 kV).
All users and the STU must provide adequate voltage control measures through voltage relays as finalised by the RPC, and ensure their effective application to prevent voltage collapse and cascade tripping. Voltage fluctuation limits and voltage waveform quality shall be maintained as specified in the Central Electricity Authority (Grid Standards Regulations), 2010.
Every Distribution Licensee must maintain a power factor of not less than 0.90 lagging at all times and provide all data required by the SLDC to ascertain reactive power flow to its distribution system. The Distribution Licensee must comply with SLDC instructions to minimise reactive power drawl from the transmission system.
Every user must ensure that metering and protection at generating stations, sub-stations, and distribution systems meet the requirements of the Metering and Protection Standard set out in Annexure F of the Grid Code. Protection relay settings must not be altered or bypassed without prior consultation and agreement of all affected users. Where bypassed by agreement, protection shall be restored as quickly as possible; if no agreement is reached, the equipment shall be removed from service immediately if it affects system security.
Disclaimer: The information contained in this Article is intended solely for personal non-commercial use of the user who accepts full responsibility of its use. The information in the article is general in nature and should not be considered to be legal, tax, accounting, consulting or any other professional advice. We make no representation or warranty of any kind, express or implied regarding the accuracy, adequacy, reliability or completeness of any information on our page/article.