Planning for dispatch efficiency
Using health checks to ensure efficiency, reduce costs and ramp up renewable energy use.
Background, challenges and context
Efficiency of dispatch in power systems is an important health check of the existing system to ensure that the incumbent system is using existing resources properly and can improve to accommodate low carbon resources going forward.
The World Bank’s Energy Sector Management Assistance Program (ESMAP) has found that, even in a relatively small system like Bangladesh, over a billion dollars could be saved through more efficient dispatch by reducing unnecessary reliance on oil and using available domestic gas more efficiently.
Absent a wholesale electricity market, it is critical that a health check is performed on dispatch practices not only to reduce costs, but also to explore ways to introduce much-needed flexibility in these systems so that variable renewable energy can ramp up rapidly without jeopardizing system reliability. Yet, dispatch diagnosis is very rarely performed in developing countries.
Research overview and objectives
The Power Systems Planning Group, part of ESMAP, plans to conduct a dispatch optimisation study in Pakistan and Nigeria, replicating a previous study it carried out in Bangladesh.
The team will establish a simple but robust methodology that can work with existing modelling tools and available data so it can be applied to a number of systems.
The research questions will include the following:
How can we set an efficient benchmark, namely, an optimised generation dispatch?
Are existing generators being used optimally to meet demand?
Is the system ready to accommodate a significant level of renewable entry?
What explains the divergence from an efficient benchmark?
What needs to change to ensure improved utilisation of existing generators? What additional measures need to be put in place to increase penetration of solar and wind?
An efficient benchmark will be established by developing a dispatch optimisation model that dispatches all generating units in the power system on an hourly basis for one or more years, and reflecting the constraints the system faced.
This optimised dispatch can then be compared with the actual dispatch. If the actual system costs and underlying generation dispatch are significantly different from the efficient benchmark, the team will be able to pinpoint the excess generation that occurred from expensive units as well as cheaper resources that were under-utilised.
To assess renewable readiness, the team will also test the adequacy of spinning reserve for each hour that is critical to accommodate variability in solar and wind resources.
A dispatch diagnosis will set out the plausible reasons behind departure of the actual dispatch from the efficient benchmark. The reasons may fall into three broad categories: poor dispatch practices, commercial constraints, and other constraints that are not captured in the modelling but had an impact on the actual dispatch (e.g. expensive generators needing certain minimum run hours in a year, available hydro not being utilised optimally due to environmental or agricultural restrictions, etc.).
These steps can lead to a set of prioritised actions that would naturally differ from system to system, but in generic terms may include enhancing dispatch practice, investing in upgrading specific transmission lines and flexible reserves (including battery storage), and allocating additional fuel/gas to the power sector. Smart grid options may also aid operators in running grids optimally, and provide inexpensive ways to get better mileage out of existing transmission systems.
The study will be conducted in close cooperation with the power system operators, which will provide data on demand, actual dispatch, transmission, etc., and with the central utilities in charge of Power Purchase Agreements (PPAs).
Data, tools, analysis, and training will be made available to relevant groups, with a key objective of the project being to ensure system operators and utilities can perform these studies routinely and apply the findings to ensure more efficient dispatch going forward.
National Power Control Center (NPCC), Islamabad, Pakistan