Scheduling and dispatch of electricity with focus on smooth grid operation & role of Load Despatch Centers under Power System Operation Corporation

The load despatch functions, earlier handled by PGCIL, have been entrusted to Power System Operation Corporation Limited (POSOCO) since 2017 and it consists of 5 Regional Load Despatch Centres (RLDCs) and the National Load Despatch Centre (NLDC).

POSOCO is a Government of India enterprise under the Ministry of Power. It was earlier a wholly owned subsidiary of Power Grid Corporation of India Limited (PGCIL). It was formed in March 2009 to handle the power management functions of PGCIL with a responsibility to ensure the integrated operation of the Grid in a reliable, efficient, and secure manner. The subsidiary was eventually made a separate company in January 2017 and PGCIL was left with sole task of setting up transmission links.

Transmission network failure and blackout of July 2012

The Northern Region Grid, which provides power to nine states in northern India including the national capital, experienced a widespread outage due to a grid disturbance that happened at 2.35 a.m on 30 July 2012.and affected the industrial/manufacturing set up, railways, metro, airports and other essential sectors. Nonetheless, about 60% of load of the Northern Region was restored by 11:00 am on the same date. Later, power supply was restored progressively and by 12:30 p.m. power was extended to most of the cities and towns through POWERGRID sub-stations. The Northern Grid was brought back to

On 31 July 2012, the northern grid collapsed for a second time, hours after the power supply was restored in the entire northern region following a disruption on the previous day. The eastern transmission lines also failed, disrupting power supply in Delhi, Uttar Pradesh, Haryana, West Bengal, Assam and Punjab, among other states.

Such incidences made it a necessity that transmission grids should be independently audited at regular interval to ensure that the grids are fail-safe.

Load Despatch Centre –

The Load Despatch Centers shall also not engage in the business of generation or trading of electricity, as par the provisions of the Act, so that they can discharge their functions free from conflict of interest. It is in this context, CERC notifies ‘Fee and Charges of Regional Load Despatch Centers and other Related Matters’ Regulations at an interval of five year on rolling basis. The Regulations have ensured an independent revenue stream and financial autonomy for POSOCO.

Even the best of technological tools provided in the form of SCADA/EMS (Supervisory control and data acquisition / Energy management system) and other offline support systems in the LDCs would require human skills and motivation for the tools to be utilized in the best manner. The human resource expenses are one of the most important and a major component of the entire expenditure of POSOCO and have been allowed separately in the Regulation. The Users comprising of Inter-State Generators, Buyers and Inter-State Transmission Licensees are availing the services of the RLDCs and NLDC and have been paying the charges of the RLDCs and NLDC. To maintain cash flow, healthy realization of the billing being done to the various users is of utmost importance for the Company. Petitions for approval of the Fees and Charges for the control period 2014-19 have been filed in the month of October, 2015, in accordance with the RLDC Fees and Charges Regulations notified by CERC on 18th May 2015.. CERC has approved the fees and charges in December 2016. Annual Charges amounting to Rs. 701 Crores have been allowed against the Rs. 1422 Crores filed with CERC for the control period 2014-19. Company may face cash flow issues following these orders. In view of the same, CERC is being approached for review of the orders.

Need of Load Dispatch Center:

As we are aware that Electricity cannot be stored to achieve economies of scale and commercially not viable as well in a large scale and therefore electricity has to be produced when it is needed. It is therefore essential that power system is planned and operated optimally & economically. This is the main objective of Load Despatch Center. LDC also ensure the smooth operation of transmission network

Objective of Load Dispatch Center:

Matching the power demand with system integrity , reliability and security of generation and transmission facilities

Regulating the system frequency.

Optimum utilization of resources.

Quick restoration of normalcy after system disturbances.

Thus the objectives of Load Despatch Department is to co-ordinate generation , transmission and distribution of electricity from moment to moment to achieve maximum security and efficiency. The functions of Load Despatch Department are Dynamic in nature. While performing the functions the policies laid down by management are strictly followed. In Maharashtra State Electricity Board (MSEB) the policies that govern the operation of Load Despatch Department are:

Economy of generation, transmission and distribution of supply of electric power to the consumers.

Continuity and high reliability of power supply.

Safety of equipment.

National Load Dispatch Centre (NLDC)

National Load Dispatch Center is the apex body to ensure integrated operation of the national power system for optimum scheduling and dispatch of electricity among the Regional Load Dispatch Centers.

NLDC ensure Integrated Operation of the Indian Power System to facilitate transfer of electric power within and across the regions and trans-national exchange of power with Reliability, Economy and Sustainability.

NLDC facilitate competitive and efficient wholesale electricity markets and administer settlement systems with involvement of cyber security.by adoption of latest technology

National Load Despatch Center shall not engage in the business of trading in electricity.

Regional Load Despatch Center (RLDC)

RLDC shall be the apex body to ensure integrated operation of the power system in the concerned region.

RLDC shall comply with such principles, guidelines and methodologies in respect of the wheeling and optimum scheduling and despatch of electricity as the Central Commission may specify in the Grid Code.

Each RLDC maintains their own dedicated website where scheduling and despatch of power within their respective control areas are handled round the clock.

No RLDC shall engage in the business of generation of electricity or trading in electricity

The RLDC may levy and collect such fee and charges from the generating companies or licensees engaged in inter-State transmission of electricity as may be specified by the Central Commission.

The RLDC shall (1) be responsible for optimum scheduling and dispatch of electricity within the region, in accordance with the contracts entered into with the licensees or the generating companies operating in the region; (2) monitor grid operations; (3) keep accounts of quantity of electricity transmitted through the regional grid; (4) exercise supervision and control over the inter-State transmission system; and (5) be responsible for carrying out real time operations for grid control and dispatch of electricity within the region through secure and economic operation of the regional grid in accordance with the Grid Standards and the Grid Code.

Number of Regional Load Despatch Centers and their area of purview across India

There are Five Regional Load Despatch Centers (RLDCs) to oversee the interstate transmission systems for the following states

Northern Regional Load Despatch Center (NRLDC) : Delhi, Haryana, Himachal Pradesh, Jammu and Kashmir, Punjab, Rajasthan, Uttar Pradesh, Uttarakhand

Western Regional Load Despatch Center WRLDC) : Maharashtra, Gujarat, Madhya Pradesh, Chhattisgarh, Goa, Daman and Diu, Dadra and Nagar Haveli

Eastern Regional Load Despatch Center (ERLDC) : Bihar, Jharkhand, Odisha, West Bengal, Sikkim

Southern Regional Load Despatch Center (SRLDC) : Tamil Nadu, Karnataka, Kerala, Andhra Pradesh, Telangana, Pondicherry

North-Eastern Regional Load Despatch Center (NERLDC) : Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Tripura

National Load Despatch Centre vesus Regional Load Despactch Centre –

As per section 28 of the Electricity Act, 2003 RLDCs are the Apex bodies to ensure integrated operation in the concerned region.

NLDC has been designated as Apex body to ensure integrated operation of National Power System vide Ministry of Power notification dated 2nd March 2005.

Further, the RLDCs are responsible for carrying out real time operations for grid control and despatch of electricity within the region through secure and economic operation of the regional grid in accordance with the Grid Standards and the Grid Code.

The RLDCs and NLDC perform two distinct functions in the form of System Operation and Market operation. Ensuring reliable operation of the electricity grids is the first and foremost task and a pre-requisite for markets to operate. Administering the wholesale electricity market at the interstate level based on CERC Regulations comes the next.

The responsibilities of RLDCs/NLDC include implementation of Availability Based Tariff (ABT), short term open access in inter-State transmission, integration of regional grids, operation of multiple Power Exchanges, Nodal agency for Ancillary Services Operations, integration of renewable energy sources, Nodal Agency for Renewable Energy Certificates (RECs) and its entire administration, Nodal Agency for Power System Development Fund (PSDF), implementing agency for the Point of Connection (POC) based transmission charges sharing mechanism, power supply regulation, etc.

State Load Dispatch Center (SLDC)

The SLDC shall (1) be responsible for optimum scheduling and dispatch of electricity within a State, in accordance with the contracts entered into with the licensees or the generating companies operating in that State; (2) monitor grid operations; (3) keep accounts of the quantity of electricity transmitted through the State grid; (4) exercise supervision and control over the intra-State transmission system; and (5) be responsible for carrying out real time operations for grid control and dispatch of electricity within the State through secure and economic operation of the State grid in accordance with the Grid Standards and the State Grid Code.

No State Load Dispatch Center shall engage in the business of trading in electricity.

The State Transmission Utility shall operate the State Load Despatch Centre until a Government company or any authority or corporation is notified by the State Government.

The State Load Dispatch Centre 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.

Responsibilities of State Load Despatch Center:

Demand Estimation for operational purpose.

Scheduling for Merit Order Despatch.

Regulating Generation Load Balance.

Schedule for Central Sector Drawl & Regulate it.

Monitor bilateral power supply agreement.

Maintain system frequency in 49.0 Hzs to 50.5 Hzs range.

Outage planning and monitoring.

Restoration procedure planning and implementation.

Reactive power management and voltage control.

Load Shedding Implementation.

Coordination with RLDC And other constituents.

Functions of State Load Despatch Centers:

(a) be responsible for optimum scheduling and despatch of electricity within a State, in accordance with the contracts entered into with the licensees or the generating companies operating in that State;

(b) Monitor grid operations;

(c) Keep accounts of the quantity of electricity transmitted through the State grid;

(d) Exercise supervision and control over the intra-state transmission system; and

(e) be responsible for carrying out real time operations for grid control and despatch of electricity within the State through secure and economic operation of the State grid in accordance with the Grid Standards and the State Grid Code.

1. The State Load Despatch Centre shall be the apex body to ensure integrated operation of the power system in a State.
2. The State Load Despatch Centre shall -
3. The State Load Despatch Centre 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.

Directions issued by the RLDC through SLDC and direction of SLDC shall be complied with by the licensee or generating company

All directions issued by the Regional Load Dispatch Centers to any transmission licensee of State transmission lines or any other licensee of the State or generating company (other than those connected to inter State transmission system) or sub-station in the State shall be issued through the State Load Dispatch Centre and the State Load Dispatch Centers shall ensure that such directions are duly complied with the licensee or generating company or sub-station.

The State Load Despatch Centre shall comply with the directions of the Regional Load Despatch Centre.

The direction of the State Load Despatch Centre shall be complied with by the licensee or generating company.

1. The State Load Despatch Centre in a State may give such directions and exercise such supervision and control as may be required for ensuring the integrated grid operations and for achieving the maximum economy and efficiency in the operation of power system in that State.
2. Every licensee, generating company, generating station, substation and any other person connected with the operation of the power system shall comply with the direction issued by the State Load Despatch Centre under subsection (1).
3. If any dispute arises with reference to the quality of electricity or safe, secure and integrated operation of the State grid or in relation to any direction given under sub-section (1) , it shall be referred to the State Commission for decision:
4. If any licensee, generating company or any other person fails to comply with the directions issued under sub-section (1), he shall be liable to penalty not exceeding rupees five lakhs.

Disclaimer: The author contributed to this article in his personal capacity. The views and opinions expressed in this article are those of the author and do not necessarily reflect or represent the views or the official policy or position of the any entity, institution and organization. Assumptions made within the analysis are not reflective of the position of any entity, institution and organization. The author disclaim any liability in connection with the use of this information. Examples of analysis performed within this article are only examples. They should not be utilized in real-world analytic products as they are based only on very limited and dated open source information.