- Grid Operations:
In many ways, today's power system must be operated to meet objectives for which it was not explicitly designed. The transmission system is operated to transfer larger amounts of energy over greater distances utilizing an increasingly higher percentage of non-traditional resources than were considered when it was built. Generation resources are more constrained and increasingly more variable and uncertain. Demand resources are now increasingly used for resource adequacy and providing ancillary services in many regions. All of these changes are occurring at a rate that is outpacing corresponding growth in transmission infrastructure. As a result, today's grid is operated much closer to the margin.
Under these circumstances, it is imperative that operators be provided with good information based on real-time data regarding the status of the system, as well as decision-making support to respond to rapid changes that might occur in the near future. The emergence of new sources of real-time data from synchrophasor measurements, asset health sensors, and forecasts of future load and variable renewable output levels, along with improved information and visibility of alarms and protection system implications, enable the possibility of providing operators with increased situational awareness and advanced decision-support tools. System operators need such tools to continue to reliably and economically operate the system in the face of emerging challenges.
EPRI's Grid Operations research program is addressing these needs by improving real-time situational awareness, developing tools that use synchrophasor and other measurements to assess the present system operating point relative to thermal, transient, and voltage stability operating limits, evaluating methods for more intelligently managing alarms, and developing tools to manage the grid through extreme events and restore the system in the event of an outage.
- Grid Planning:
Traditional power system planning methods and tools are becoming less effective in today's power system environment. Transmission owners and operators not only need to plan for future demand growth and increasingly uncertain generation portfolios, but also to provide transmission services from generation resources that include significant portions of variable generation (VG) technologies that are often remote from load centers and have significantly different dynamic behavior from synchronous generation. The challenge of meeting reliability requirements with the changing landscape and increasing levels of uncertainty may necessitate adjusting and augmenting transmission planning criteria and methods.
Transmission planners are also increasingly tasked with considering deeper and varied contingencies requiring screening of many more potential contingencies and prioritizing the contingencies for more detailed analysis. They also need to perform analysis of "special" circumstances such as the impacts of geomagnetic disturbances on system reliability, and non-traditional impacts such as high levels of harmonic distortion. Some of these more advanced contingency analyses may also require closer coordination and explicit integration of protection system models in planning models.
Resource planners are also increasingly challenged as environmental regulation forces the retirement of some conventional generation, as supply resources become more variable and uncertain, and as distributed and demand-side resources become more viable. Additionally, demand response and extreme temperatures in traditionally shoulder load periods are increasing the uncertainty in load levels at specific points in time. As a result, resource adequacy planning methods may require more consideration of the operational uncertainties associated with renewable energy and load forecast errors.
- Bulk Power System Integration of Variable Generation:
Recently there has been a significant increase in the implementation of renewable energy, due to both policy decisions such as state-mandated renewable energy standards and federal air and water standards, along with improved economic viability for these resources. Much of the estimated development of renewables comprises variable resources such as wind generation and solar photovoltaics (PV), which when integrated with the grid, create new challenges for maintaining reliable system operation. Future projections are that a more significant build-out of these variable renewable resources is likely at both the transmission and distribution levels.
With these developments, power system planners and operators require new tools and resources to ensure a reliable, sustainable, and cost-effective supply of electricity to consumers. New tools needed include improved and/or new sources of system flexibility to respond to and accommodate the increase in energy variability and uncertainty, the development of additional transmission infrastructure to deliver energy from remote locations, and planning and operational methods and software to effectively plan and operate the bulk system with these new resources, many of which may be at the distribution level. EPRI's Bulk Power System Integration of Variable Generation (VG) research program addresses these needs and directly supports EPRI's Research Imperatives #2 "Integration of Dynamic Customer Resources and Behavior" and #3 "Integrated Power System and Environmental Modeling Framework."