SLDC, now a separate accounting unit of Punjab State Transmission Corporation Limited (PSTCL), is a state of art Computerized Control centre established in August 2002 at Ablowal, Patiala. It ensures integrated operation of the power system of Punjab with the Northern Region Load Dispatch Centre of India. Under Section 31 of the Indian Electricity Act, 2003 it is mandatory for the States to establish their own Computerized State Load Dispatch Centres for performing the following functions (as specified under Section 32 of Indian Electricity Act 2003): -

  • To ensure integrated operation of the Power System in the State.

  • Optimum dispatch of Electricity.

  • Monitoring and control of system parameters to maintain healthiness of the Power System at all times.

  • SLDC shall keep accounts of the quantity of electricity transmitted through State grid.

  • Exercising supervision and control over the intra-State transmission system.

  • SLDC may levy and collect such fee and charges from the generating companies and licensees engaged in intra-State transmission of electricity as may be specified by the State Commission.

  • Analysis of tripping/disturbances and facilitating immediate remedial measures.

SLDC organization has following Departments :

In the post unbundling scenario, this office is responsible for the following operations:

  • Optimum scheduling and dispatch of electricity within the state.

  • Monitoring grid operations.

  • Keeping accounts of quantum of electricity transmitted through state grid.

  • Exercising supervision and control over the intra state transmission system.

  • Carrying out real time operations for grid control and dispatch of electricity within the state through secure and economic operation ofthe State grid in accordance with Grid Standards and State Grid Code.

  • Under this project, 750 No. Availability Based Tariff (ABT) meters and 450 No. Conventional Energy Meters (CEM) have been procured. ABT meters have been installed at interface/boundary points of PSTCL with PGCIL, BBMB, HP, PSPCL & IPPs to calculate the amount of energy transmitted through boundary points and for calculation of overall transmission losses of PSTCL. Energy Losses are calculate amount of energy transmitted through boundary points and for calculation of overall transmission losses of PSTCL. Energy losses are being calculated from Jul-2017 onwards by energy accounting cell. Also, CEMs have been installed at 400KV, 220KV and 132KV substations of PSTCL for energy audit purposes.

    Further, new secure meters are being installed under SAMAST scheme at various interface/boundary points of PSTCL with PGCIL , BBMB, HP, PSPCL, IPPs & RE plants. The data of these meters will be integrated with Control Centre of SLDC and real time data of these meters will be available in SLDC Control Room.

    All the reports and accounts that are now prepared manually by SLDC will be done through software after implementation of SAMAST.

Open Access

Open Access office under Chief Engineer/SLDC, PSTCL, Patiala is a nodal agency in state power utilities for grant of short term open access to all eligible customers & consumers of PSPCL.

Open Access is being granted in non-discriminatorily by PSTCL to all the eligible open access customers embedded in Transmission and Distribution system of PSTCL & PSPCL as per provisions of Electricity Act-2003 and Open Access Regulations issued by Punjab State Electricity Regulatory Commission (PSERC) and Central Electricity Regulatory Commission (CERC) from time to time. Open Access office also deals with the UI/ Deviation Settlement based energy accounting of Open Access customers transacting power on short term/medium term/long term basis and IPPs selling power to PSPCL on long term basis. Besides records are maintained for energy scheduled under open access, UI/ Deviation and assessment of open access charges.

Present Status (as on 10.04.2023)

Short Term Open Access for wheeling of power has been granted to 2 no. captive consumers for intra-state wheeling of power from their own Captive Power Plant(s) under bilateral transactions. (Total 7 MW at injection end)

Short Term Open Access for inter-state purchase/sale of power through collective (power exchange)/ bilateral transactions has been granted to 446 no. OA Consumers (out of which only 30 no. consumers (total 310.46 MW) are registered with SLDC as on date). No consumer is active for purchase of power under collective transaction.

Long Term Access has been granted by PSTCL to one no. Open Access consumer for purchase of power under Inter-State Bilateral Transaction (capacity-35 MW). Medium Term Open Access (MTOA) has been granted to 5 no. generating units of one no. captive consumer , 3.9 MW under MTOA)

To know about guidelines, procedure & formats for grant of Open Access, click here.

It is mainly looking after implementation, Updation, Up-keep and maintenance of SCADA system in PSTCL. In addition other jobs such as implementation of ABT based Boundary Metering scheme in Punjab Procurement of RTUs for PSTCL substations and maintenance hosting of SLDC Website etc. are also being handled by this office.

Supervisory Control and Data Acquisition /Energy Management System (SCADA/EMS) commissioned by M/s. Power Grid Corporation of India Limited (PGCIL) in Northern Region on Unified basis is operational at SLDC, Patiala since 2002 and real time status of the grid is available to the load dispatchers around the clock which further helps them to take corrective actions for operating the grid in efficient manner. For better viewing of data at control centre, a large display screen i.e. Video Projection System (VPS) has been installed. Further to ensure Uninterrupted Supply to the SCADA/EMS hardware, the provision of Uninterrupted Power Supply (UPS) of sufficient capacity has been made at the control centre. Existing SCADA/EMS related hardware and software supplied by M/s Areva has been upgraded by M/s Siemens System. Provision of backup control centre for main SLDC control centre has been made under the new system installed by M/s Siemens Ltd.

At present, RTUs at 169 Nos. of 220kV & 132kV substations of PSTCL have been provided for remote data acquisition and control from the Control centres i.e. Area Load Control Centres at Jamsher (Jalandhar) & Lalton Kalan (Ludhiana) and State Load Control Centre at Ablowal (Patiala) in Punjab. Besides RTUs, data is being acquired from 14 Nos. SAS (Substation Automation Systems) at 400kV & 220kV Substations & IPPs and also tender enquiry no. STQ-7065 for 2 No. SAS for Budhlada 220kV and Gurdaspur 220kV is under process. Recently, tender for the Design, Supply, Commissioning and Integration of RTUs at 21 Nos. S/stns has been floated vide Tender Enquiry No. 04/SLDC-D/2022.