To attain least-cost generation, transmission, and delivery of electricity at a reliable level, close coordination between generation and transmission operation and planning is fundamental. Optimizing these sectors in isolation can miss integrated generation and transmission solutions that are cost-optimal while meeting reliability targets. Before the introduction of competition, the level of coordination was sufficient—but competition forced separation of the generation and transmission functions, even within vertically integrated utilities. Nowadays, generation companies act independently, dealing at arm’s length with transmission planners. However, different groups (transmission planners and generation planners), within the same region—or even company—and across regions need to coordinate and anticipate others’ decisions to attain better global long-term development. The same needs are emerging in integrated systems where unaffiliated distributed resources are appearing at the grid edge. Such unbundled and distributed systems are also fraught with uncertainties, which, if inadequately considered, will lead to plans that are not resilient and cannot adapt in a way that maintains economic and reliable operations.
These challenges, referred to here as the coordinated expansion planning (CEP) problem, have come into focus over the last few years for several reasons, including deeper penetration of renewable energy sources, integration of emerging storage technologies, electrification of the transport sector, increased interdependencies with other sectors (for example, gas), and increased distributed generation in distribution grids. These changes result in increased short- and long-term uncertainties as well as a need for increased modeling fidelity to represent temporal dynamics more accurately (for example, hourly or sub-hourly intertemporal couplings in expansion models). These challenges, together with the progress in computational resources, have prompted the development of sophisticated tools able to produce expansion plans that not only approach system optimality, but are also flexible and robust against the various planning and operating uncertainties.
This report provides an in-depth view of the state-of-the-art methods and tools to produce coordinated expansion plans. In addition, it identifies the research and development needs for the new generation of coordinated expansion planning models and tools.
The report begins with some introductory concepts and a general layout; it is followed by several sections that cover specific aspects of the CEP problem. Together the sections give an integral perspective on the ongoing and future research efforts on the CEP problem. However, each section has been written to be read independently, if the reader is interested only in a particular aspect of the problem.
Authors Durgesh Manjure et al