Tata Power Delhi Distribution Limited (TPDDL), which supplies power to about 1.44 million consumers, is among the few Indian discoms to launch an automated demand response (ADR) project for managing grid stress situations. This is being undertaken to demonstrate its technological capabilities, understand consumer behaviour, act as a case study for working on differential tariffs and financial incentives, and help in scaling up processes.
TPDDL is one of India’s leading power distribution utilities in terms of the adoption and deployment of IT initiatives. It has employed various such interventions to reduce aggregate technical and commercial (AT&C) losses, including en-ergy audits up to the distribution transformer (DT) level, the implementation of high voltage distribution systems and low tension aerial bunched cables, the replacement of electromagnetic meters with electronic meters, and the introduction of automated meter reading for high-revenue consumers. The discom has engaged in aggressive enforcement activities with scientific inputs and analyses, and has also taken up network augmentation and optimisation with robust maintenance practices.
Benefits of ADR
Discoms across the world are increasingly focusing on utilising ADR mechanisms to maintain grid reliability and manage load growth on the basis of real-time energy demand information. Such a mechanism also provides incentives and technical assistance to consumers investing in energy management technologies and enables them to undertake demand response (DR).
ADR has various end-to-end solutions for utilities in different segments like remote metering, distribution, customer service and operations. In remote metering, smart meters enable automated meter discovery, on-demand reading, communication management and bill scheduling. In distribution, ADR helps in load profiling and balancing, energy forecasting and conservation, blackout prevention, outage detection and restoration, revenue protection through tamper detection, and transfer optimisation. In the customer service segment, ADR leads to billing accuracy, pricing flexibility, remote service management, granular energy consumption on a daily basis, and reduced call centre loads. In the operation segment, it helps in direct load control, remote connections or disconnections, and outage information.
Like other discoms, TPDDL also faces the chal-lenge of uneven demand. During 2014-15, the discom reduced its peak load by 272 MW for 500 hours, which helped avoid the new power purchase agreement requirements. In the same year, it could not meet its power demand for around 205 hours from the normal schedule due to transmission constraints, the shutting down of generators, etc.
In light of the load imbalance, TPDDL undertook a load curve analysis based on the demand from the industrial and domestic segments. This revealed that the peak demand from the industrial segment was for about 10 hours during the day , and the demand was higher during summers than winters. Meanwhile, the residential load came mainly during late evening in summer and in the morning during winter.
To meet unforeseen contingencies in power demand, TPDDL launched an ADR project in January 2014 using smart meters. This has received regulatory approval and involves ADR infrastructure using DR servers and site controllers.
TPDDL’s ADR project consists of a radio frequency mesh network spread over an area of approximately 250 square km, with 195 smart meters, 35 routers and three collectors. It also includes a meter data management system (MDMS) that is integrated with other IT and operational technology applications like outage management system (OMS), and systems, applications and products (SAP).
The use of smart meters is central to the project. These meters can interact through low voltage power line communication and have the capability of fetching data at 15-minute intervals. Single-phase smart meters can detect higher voltages at the consumer end. TPDDL conducted pilot projects for programmable logic control (PLC)-based smart meters that helped identify underloaded transformers, which were subsequently removed. PLC-based smart meters can be used for consumer indexing as well. The company brought in balancing in the system load, which led to a drastic reduction in AT&C losses. The DT-wise real-time calculation of AT&C losses and energy audits also allowed for unidentified drawals from the grid to be checked.
The ADR process follows a series of steps. In TPDDL, there is no integrator and actual power deductions are calculated on the basis of real-time data provided by smart meters. The process begins with the utility user initiating the DR event through ADR’s graphical user interface. This directs the DR management system to alert the concerned parties, which include the end-users of the DR programme, the MDMS and concerned utility stakeholders. The MDMS processes this data and a summary report of power shedding for each customer is prepared. The final step is the preparation of bills by the utility on the basis of billing data.
The consumer enrolment process for ADR involves the identification of critical and non-critical load through site audits and the installation of control wiring. A DR event notification is provided to consumers, who have the freedom to choose whether to participate in an event or not. Hence, the shedding of non-critical load is done only for participating consumers.
The intimation about the DR event is provided four hours in advance, after which consumers can choose to opt out through an SMS or email. The project involves data transmissions at 15-minute intervals to the TPDDL data acquisition system. A customer portal has been prepared through a mobile application to provide real-time intimations to consumers in the event of a breach in the set thresholds. Along with this, baselines of 5/10 have been used for morning adjustments. The project involves real-time outage notifications to SAP as well as integration with the OMS.
The ADR system uses meters with GSM and GPRS modems connected to the communication and application servers. Raw data is entered in the database for being analysed through these servers, which are further connected to the billing server to generate billing information and prepare management information system and other reports.
This data is used by the analysis team to identify discrepancies and is finally sent to the enforcement team. The information about probable cases of meter tampering is sent to the SAP software for further action. This method has various benefits, including improved billing, enhanced security (allowing the detection of tampered meters), and effective energy management through profile data graphs and accurate meter reading, thus leading to improved energy auditing.
As of September 2015, over 550 consumers had been audited under this project and 162 consumers were connected to ADR. Smart meters had been installed for 195 consumers. A total of 17 ADR events had been conducted and a total non-critical load of 11.5 MW was connected. In August 2014, a maximum power shedding potential of 7.2 MVA was achieved. Through ADR, TPDDL was able to reduce its consumer load by 12.5 per cent, to 22.5 per cent of the aggregate peak load. Around 18 per cent of the sanctioned load of the industries connected to TPDDL can be reduced through DR.
The way forward
TPDDL is involved in a number of demand-side management initiatives for achieving load balance. Apart from ADR, the utility is also providing home and building automation services. This has the benefit of reducing peak demand with no add-itional investments and enhancing revenue generation capacity. It also has advantages for consumers in the form of energy savings and reduced electricity bills through the use of real-time information. The additional power can be utilised to cater to further load growth requirements.
Going forward, TPDDL plans to cover all DT-level meters under its smart metering initiative. Its future plans include the development of a smart grid vision through the increased use of DR, for which it plans to create a platform for smart applications like charging electric vehicles, storing energy, building energy management systems and powering street lights. A reduction in manual processes, real-time energy information access for consumers, and dynamic tariff and payment options are other steps that the com-pany is planning to take.
To introduce technology in its distribution segment, TPDDL intends to focus on grid management and grid intelligence, for which enterprise asset management, distributed intelligence sensing, and pervasive communications and analytics are essential.
Based on a presentation by Sujay Kumar Saha, Head, Demand Side Management, TPDDL, at a recent Power Line conference