India: Use of coal generation as a flexible source to balance variable renewable energy sources
6-7 March 2018 at Northern Regional Load Despatch Centre, Katwaria Sarai, New Delhi
8 March 2018 at NTPC Power Management Institute, Noida, Delhi
Colin Henderson updates us on the recent USEA/USAID Workshops in Delhi and as ever, in India, the welcome was warm, the food wonderful, and travel by car exhilarating.
This consisted of two back-to-back events: a two-day “bootcamp” workshop, for executives from State Load Dispatch Centres, the Power System Operation Corporation (POSOCO) Ltd and the Central Energy Authority. The second, similar, event was for specifically for executives from NTPC and the Gujarat State Electricity Corporation Ltd. [Two of NTPC’s plants, a 210 MWe unit at Ramagundam and a 500 MWe unit at Jhajai, are participating in a GTG coal flexing pilot programme.] Participants from other load despatch centres and power plants participated in the events via internet link.
Contributions from Indian speakers showed that 63 GW of renewable capacity is currently installed on the Indian power system. Total capacity is around 330 GW. Rate of variation of load on the system is typically 250 MW/minute, but can be twice that.
The workshops began with introductions by USAID and POSOCO or NTPC representatives and Sara Burback of USEA, who organised the events. Apart from myself, presenters were Bernd Okkels, Head of Instrumentation and Control, Ramboll Power Generation; Nikhil Kumar, Managing Director and Principal, Intertek; Douglas Hilleman, Principal Engineer, Intertek; Volker Schuele, Manager of Coal Plant Flexibility, GE (based in Germany); and Mahesh Kendhe, Marketing and Strategy Leader, Power Services, GE India. All were highly knowledgeable and gave detailed presentations (listed below), which led to valuable discussions with the recipients at both workshops.
- Introduction to Improving Coal Generation – Nikhil Kumar, Managing Director and Principal – Intertek and Doug Hilleman, Principal Engineer – Intertek
- Key Elements of Coal Generation Flexibility – Bernd Okkels, Head of Instrumentation and Control – Ramboll Power
- Case Study: American Experience – Modifying Coal Plants for Generation Flexibility – Doug Hilleman, Principal Engineer – Intertek
- Changes made by grid operators: Understanding Plant Capabilities and Response for Adhering to Grid Management Procedures – Technologies options for production – Case study
- Nikhil Kumar, Managing Director and Principal – Intertek and Sanjeev Duggal, General Manager of Marketing & Strategy – GE India
- Increasing the Flexibility of Pulverized Coal Fired Plants – Colin Henderson
- Increasing the Flexibility of Other Types of Coal Plants – Colin Henderson
- Costs Associated with Flexibility Measures from the System Operator’s Perspective – Mahesh Kendhe and Volker Schuele, GE
- Modifications to Operating Procedures to Meet Flexibility Requirements – Doug Hilleman, Intertek
At the end of the workshops, attendees formed themselves into small groups to develop strategies and actions that they would need, based on the knowledge gained from the presentations, to implement greater use of flexible coal as a balancing source for variable renewable generation. Presentations were then made to the all participants and speakers for comments. Their written suggested plans constituted a key deliverable by USEA to USAID.
Main points discussed
It was apparent from the presentations and discussions during them that the coal power plant operators currently regard 50% load as “low”, but that, within 4-5 years, they recognise that they will need to reach down routinely to 30% load. Means to achieve this were described by the training team. Even 10% was demonstrated in Germany, but it appears not to be necessary to reach so low for some time in India. The Indian operators took fully on board that enabling efficient minimum load operations would be important in minimising the number of plant shut-downs and start-ups. One of the presenters pointed out that the relative costs of hot, warm and cold starts was 1:2:4, from all effects (i.e. efficiency loss and life consumption of components).
An interesting study by one of the speakers found that ultrasupercritical (USC) plants would be more penalised in efficiency by operating at low load than subcritical plants would be. However, the absolute efficiency at low loads would still be higher for USC.