To meet decarbonization goals, we need to reframe how we think about the power delivery system. Instead of thinking about it as three more-or-less independent modules (bulk transmission, sub-transmission, and distribution), we need to begin thinking of power delivery as an integrated system that requires top-down and bottom-up coordination of functions, services, and information.
The bulk transmission, sub-transmission, and distribution components of the power delivery network have historically been planned and operated largely as independent entities. The Independent System Operator is responsible for planning and operating the bulk system, transmission companies are principally responsible for the sub-transmission system, and electric distribution companies oversee distribution. Coordination amongst these entities has largely been restricted to the points of interface, with planning procedures and operating protocols designed to protect each set of network components from conditions on the other.
The limits of this historical planning and operating paradigm are evident. The complexity of the interactions amongst the three levels of the network is increasing, and the boundaries between these levels are quickly becoming blurred. Power now regularly flows from parts of the distribution network onto the sub-transmission network and up to the transmission network. Additionally, requests to interconnect at the distribution level are affecting the transmission network, and requests to interconnect at the bulk level are impacted by conditions on the sub-transmission and distribution networks. While allowing system modification to be driven primarily by system interconnection requests was fine when the number of requests and subsequent modifications were small, the volume of requests is now materially changing the region’s delivery infrastructure, and these changes are occurring without any effective way to measure the expected efficiency of the resulting system or its ability to support state policy mandates through time.
Experience interconnecting resources and performing planning studies reveal several limitations of the existing paradigm:
- Not enough information exchange amongst the principals responsible for planning the system components
- Limited consideration of the potential supporting role of, and impact of, demand-side participation, distributed power generation, advanced control and FACTS (and D-FACTS), and energy storage
- Inability of deterministic approaches to power system planning to adequately respond to the increasing penetration of renewable energy supply
- Need for greater use of probabilistic methods to address stochastic features and to address uncertainties associated with the overall system
How then to move forward? Based on our experience interconnecting resources and performing planning studies, to enhance the planning process, we need to do the following:
- Expand stakeholder participation to include key representatives of all users of the power delivery network throughout all steps in the planning process
- Broaden the range of power delivery system expansion alternatives considered, recognizing bottom-up and top-down impacts, including how upgrades at the bulk level can positively or negatively impact performance and costs down stream, and vice versa
- Consider the impact of power delivery system changes on the markets, congestion costs, and cost of delivering public policy goals
- Perform a comprehensive risk assessment of the power delivery system plan
- Undertake proactive, rather than reactive, system upgrades in support of public policy goals (strategic infrastructure development)
- Recognize and maximize benefits from economies of scale in equipment purchase, deployment, and facility sizing
- Build in flexibility to accommodate new technologies and clean energy resource expansion
- Develop a practical and robust power delivery system plan that recognizes that the system is being built into an uncertain future and that it should be able to efficiently accommodate multiple future states without incurring material costs (value of flexibility and optionality)
- Engage the FERC on tariff structures that logically and efficiently manage interconnection requests across all levels of the power delivery system
Successfully planning a region’s future-state power delivery network must emphasize functions, services, and information exchanges across transmission, sub-transmission, and distribution interfaces. To do this effectively, we must reframe planning from an integrated power delivery system perspective.
We are looking forward to continuing the conversation,