Communication has always played a critical role in the power sector and has become even more important in the context of smart grid infrastructure. The communication network in a power system has the important task of conveying information with the aim of ensuring stable electricity supply.
At present, the need for communication in the power sector is covered under the Indian Electricity Grid Code (IEGC). However, it does not talk about a strategy for planning the communication system, the roles and responsibilities of various organisations, and the standards/protocol to be followed, which are vital in view of the criticality of an effective communication system for the power sector.
To address these issues, the Central Electricity Regulatory Commission (CERC) recently formed a task force for preparing a report on a communication system for the power sector. The following are the key highlights of the report…
During the initial stages, power systems in India were not only small in size, but also less complex in structure and easy to operate and control. Generating stations were, by and large, set up near demand centres and there were limited grid parameters to be monitored and controlled. The data, telemetered or manually acquired, from the power system was displayed on mimic panels, analog meters, etc., and monitoring and control were invariably done on the basis of the judgement and intuition of operators. Operation and control instructions were conveyed verbally by the operators.
The establishment of the national grid will undoubtedly bring economic benefits and improve the reliability of power supply, the report notes. However, with the growing complexity of the power system, grid stability will be impacted. The increasing penetration of renewable power, particularly solar and wind, and their inherent variability and unpredictability, also pose a challenge to safe and secure grid operations.
Thus, with the increase in the size and complexity of the grid, the communication needs of the power sector have increased significantly. To monitor and manage such a large integrated grid, it is essential to have reliable real-time data along with voice communication. This necessitates the availability of a robust and extensive communication network.
The report identifies several functions of the communication system. Communication systems for the power sector should facilitate grid safety, security, stability and reliability, ensure economic operation and optimisation of the system, and make optimal use of resources.
Planning communication networks
The commonly deployed communication media in the power sector include power line carrier communication, wireless radio frequency, microwave, optical fibre cable (OFC), and cellular and satellite channels for various applications. As the power sector’s communication network is by and large aligned with the transmission system, the report notes that it is essential to plan the communication system and the respective transmission networks in tandem. The communication system should be adequate to cater to the entire communication needs and should come up within the same time frame as the transmission system. Therefore, while planning a transmission system, the report says that if the future requirement for data is envisaged to be large, a multichannel mode of communication may be planned outright, even though the immediate requirement may be limited.
The planning of a communication network involves the formulation of technical standards and guidelines of communication and development of an adequate and reliable communication network that is commensurate with the growth of the power network. It also includes reviewing the adequacy of the existing communication network in accordance with the standards/norms and planning criteria.
Role of various agencies in planning
The task force has identified important roles and responsibilities for various entities. Among other functions, the Central Electricity Authority (CEA) will be responsible for formulating and notifying technical standards/protocols for the communication system and formulate a perspective plan based on the communication requirements of the sector, duly considering the smart grid concept for interstate as well as intra-state transmission systems.
The central transmission utility (CTU) will carry out communication planning from time to time as per the requirement of major interstate transmission systems, including interregional schemes that fit in with the perspective plan developed by the CEA.
The regional power committee (RPC) secretariat will monitor instances of non-compliance with the CERC (Communication System for Inter-State Transmission of Electricity) Regulations, 2016 and try to sort out issues in the respective regions. The National Load Despatch Centre (NLDC) will be responsible for preparing and issuing guidelines on interfacing requirements with respect to terminal equipment, remote terminal units, supervisory contro and data acquisition system, automatic generation control, etc., and data communication from the user’s point to the respective control centres based on the technical standards issued by the CEA.
The state load despatch centres (SLDCs) will be the nodal agencies for integrating the communication system with the state transmission utility (STU) network. They will be also responsible for interfacing the telemetry system at their end. Requesters and users including renewable energy generators will be responsible for providing compatible equipment for uninterrupted communication with the control centres concerned.
The STU will be responsible for planning and coordination for the development of a reliable communication backbone within a state for data communication among SLDCs, discom control centres along with generating stations, substations of the STUs and other transmission licensees, independent power producers, and renewable energy generators.
Methodology for planning
All STUs and users will supply the required data to the CTU to enable the formulation of a communication plan. With a view to achieve uniformity and compatibility at all interfaces, the technical standards for all communication subsystems, including terminal equipment as well as communication media, will be formulated. Guidelines and procedures will be framed for the operations and maintenance of communication systems. Equipment safety and cyber security will be an inherent feature of the planning and implementation of communication systems. The report also notes that laying of optical ground wire (OPGW) on a transmission line at the construction stage is cheaper than the cost of OPGW involving re-engineering on the existing transmission lines.
Considering this, as well as the downward trend in the cost of optical fibre and the marginal percentage cost difference of transmission lines with and without OFC, the task force has recommended that, as a general guideline, all regional substations at the 132/110 kV or above level and all new 132 kV and above transmission lines may have OPGW wherever needed for wideband communication.
Smart grid and cybersecurity
The task force is of the view that planning and development of the communication system should be based on smart grid requirements and technologies, and planners may consider broadband connectivity up to the pooling stations. It is imperative that cybersecurity be integrated into the systems from the very beginning and security needs be addressed at all levels of the architecture. The task force is of the view that a nodal agency, preferably the NLDC, may monitor cases of cyberattacks and discuss the necessary preventive and remedial actions at the RPC forum.
The report notes that regulations with regard to communication in the power sector can be framed as a separate chapter under the IEGC. Alternatively, the CERC may frame regulations relating to the communication system for interstate transmission of electricity and the state electricity regulatory commissions (SERC) may frame similar regulations for power systems within the state. The secretariat of the Forum of Regulators may take up the matter so that the SERCs also frame regulations pertaining to the communication system for intra-state electricity transmission.