Section 6 in Tamil Nadu Electricity Regulatory Commission Tamil Nadu Electricity Distribution Code
6. Planning process.
- The system planning considerations are:(1)Load Forecast: It commences with a forecast of the anticipated load requirements (both demand and energy). The Licensee shall forecast the demand for power within the area of supply, annually or more frequently, if required by the Commission, in each of the succeeding five years. The Licensee shall prepare a demand forecast and generally follow the procedures set out herein. The licensee shall create a database of loads for each consumer category and for each distribution substation and update it annually.(2)Load Research: The Licensee shall develop a load research program with the objective of obtaining customer load profile data that provides the usage characteristics of specific appliances, consumers and group of consumers. This load research will also facilitate,(a)Demand status according to end use at the hour of system peak, daily, monthly, seasonally or annually(b)Hourly end use demand for the day of the system peak, monthly, seasonally or annually.(c)Hourly end use demand for the average day of the system peak, monthly, seasonal or annually.(d)Category wise diverse or coincidence factors and load factors.(e)Total energy consumption for each category of consumer by month, season or year.(f)Category wise non-coincident peak demands.(3)Load Data: From the metering data collected at each connection point with the transmission system, the Licensee shall develop load curves for the area fed and also the system load curve for the area of supply in point by applying a suitable diversity factor. By reconciling the figure for actual energy sales with the drawal based on the metering data [compiled] [Substituted for the expression 'complied' as per Commission's Not if. No. TNERC/DC/8- dated 8.2.2008 (w.e.f. 27.2.2008)], approximate losses in the system may be arrived at for any period. This data shall be furnished to the STU and the Commission annually. All the consumers with a demand of 1 MW and above seeking connection shall furnish their load data to the Licensee, as detailed in Annexure I. The Licensee shall exercise special care in monitoring the actual development of loads in respect of consumers who desire to contract for loads of 1 MW and above at any single point. On demand by the consumer seeking connection, the Licensee shall furnish relevant system data as detailed in Annexure - II. The Licensee shall update the system data at least once in every six months.(4)Forecast Methodology: The Licensee shall formulate the long-term demand forecast taking into account the previous financial year ending March 31st as the Base Year and projecting the demand over the succeeding five years.(a)Energy Sales per tariff class shall be projected in the forecast period over the corresponding figures relating to the Base Year by adopting a suitable methodology, such as considering the trend for the previous five years.(b)The projections shall take into account assumed normal growth for non-specific loads, specific and identified loads of 1 MW and above and also the effects if any, of Demand side management and Loss reduction measures.(c)The Licensee shall compare the aggregate energy requirement at each of the connection points with the transmission system after accounting for system losses. The future peak load in each of the years in the forecast period may be derived using an Annual Load Factor.(d)The Licensee shall take into consideration any authenticated report on demand forecast or Power survey carried out by agencies like Advisory Board on Energy, Planning Commission, Central Electricity Authority, STU, Commission, CERC and Government of Tamil Nadu. The Licensee shall forward the long term demand forecast for the area of supply on an annual basis to the STU and the Commission, along with the details as indicated below.(i)Data.(ii)Methodology(iii)AssumptionsThe Licensee under the conditions of the licence shall co-operate with the STU in the preparation of demand forecasts for the State of Tamil Nadu. The format for the demand and energy forecasts shall be specified by the STU.(5)Planning Criteria and performance bases: The planning criteria for the distribution system as specified [by the Commission] [Substituted for the expression 'by Commission' as per Commission's Notification No. TNERC/DC/8-8 dated 8.2.2008 (w.e.f. 27.2.2008).] shall form the basis. The performance bases to be considered in the system planning are as follows:(a)The Distribution performances established herein shall be implemented in a manner so as to ensure that no entities are forced to achieve goals beyond the capability and limitations of the current system in the immediate future while continuing to strive for the higher standards by improving their system in the long term. As for the existing arrangements, the implementation can be in stages and shall be determined by the Commission.(b)The capacity of step down transformers used in the distribution system and the layout of bus bars, switchgear, transformers, capacitors, earthing system, surge arrestors, control panels, station battery, fire extinguishers and other accessories required for the protection and safe operation of the substations shall as far as possible be standardized by the Licensees and shall conform to the guidelines and principles contained in the Code. The Commission, in specific cases and to ensure uniform adoption, can however specify the standards to be adopted.(c)While planning the distribution system, the Licensee shall examine the cost effectiveness of loss reduction measures without compromising the security standards. The Licensee shall take measures to reduce the length of low tension bare conductor, overhead lines, wherever cost effective and these shall include but not limited to the following:(i)Achievement of HT: LT ratio to the level of 1 to 1.5(ii)Laying of underground cables(iii)Increasing the number of low loss distribution transformers.(d)Substation Design Criteria: HV substations, Sub transmission, primary and secondary distribution shall be designed taking into account the following factors:(i)Safety of Operating Personnel(ii)Adequate cross section of Busbar to meet the electrical and mechanical requirements.(iii)Mechanical and electrical interlocks to prevent inadvertent operation of equipments including switch.[iii-a) Adequate Protection System with proper insulation co-ordination] [[Substituted as per Commission's Notification No. TNERC/DC/8-8 dated 8.2.2008 (w.e.f.27.2.2008).before substitution it was as under:The distribution system shall be properly earthed in accordance with the Indian Standards in force, substation earth mats shall be designed to provide the required earth resistance and limit the ground potential rise limited by Touch and Step potential criteria as per standards]](iv)Adequate Flexibility in operation and maintenance.(v)Operation and Maintenance needs.(vi)Space for future expansion(e)Distribution Line Clearances: Overhead lines shall comply with the safety measures specified by the Authority under section 53 of the Act.(f)Earthing : The distribution system shall be effectively earthed in accordance with the [Indian Standards in force, substation earth mat shall be designed to have a low overall impedance / resistance and to have a minimum transient ground potential rise (TGPR) during fault, giving rise to only permissible safe touch and step potential] [Inserted as per Commission's Notification No. TNERC/DC/8-8 dated 8.2.2008 (w.e.f. 27.2.2008).]. All individual earth electrodes, earthing pits and interconnection arrangements shall be correctly installed and maintained. The bodies, cases, trucks and enclosures of all equipment shall be properly earthed in accordance with the system requirements and equipment ratings. Metallic line supports of overhead lines, cable sheaths and shields shall also be earthed in a proper manner. Connections may be compressed using crimping tool, welded, braced, or bolted using suitable lock washers/locknuts. Bolts should not be used for buried connections
