System Impact Studies for Near 100% Renewable Energy Systems Dominated by Inverter Based Variable Generation

Abstract

The demand for low carbon energy calls for close to 100% renewable power systems, with decarbonization of other energy sectors adding to the anticipated paradigm shift. Rising levels of variable inverter-based renewable energy sources (VIBRES) are prompting questions about how such systems will be planned and operated when variable renewable generation becomes the dominant technology. Here, we examine the implications of this paradigm shift with respect to planning, operation and system stability, also addressing the need for integration with other energy vectors, including heat, transport and Power-to-X. We highlight the knowledge gaps and provide recommendations for improved methods and models needed as power systems transform towards 100% VIBRES.

Halfway to Zero: Progress towards a Carbon-Free Power Sector

“…• As weather-dependent, inverter-based resources including solar and wind progressively deploy, extensive attention to grid infrastructure and operations is required to ensure power system flexibility, reliability, resilience, stability, and security (DOE 2017a;2017b;Holttinen et al 2020;Frew et al 2019; National Academies 2021b). • Battery storage is likely to be a core response to these concerns in the near term, but many forms of flexibility can be leveraged-not only other forms of storage, but also load responsiveness and supply flexibility (Williams et al 2021;Jenkins, Luke, and Thernstrom 2018;Jacobson 2020;Gorman et al 2020;Strbac et al 2020).…”

“…• Significant new transmission infrastructure (and more-efficient use of existing assets) may be needed to integrate growing shares of wind and solar; interconnection processes may need to be reformed (Williams et al 2021;Joskow 2020;Brown and Botterud 2020;MacDonald et al 2016;Bloom et al 2020;National Academies 2021b;ESIG 2021;Caspary et al 2021). • Wholesale power markets may need to transform to accommodate the changing supply and demand conditions; new technology standards and capabilities as well as planning and operating models and procedures would be needed (Ela et al 2021;Holttinen et al 2020;Frew et al 2019;DOE 2017a;EPRI 2021). • Siting and permitting innovation, streamlining, and procedures-at the local, state, and national levels-will be needed to manage a step-change increase in new supply and delivery infrastructure (Williams et al 2021;Larsen et al 2020;Mai et al 2021).…”

Model Predictive Control for Microgrid Functionalities: Review and Future Challenges

“…In fact, the greatest challenges faced by the energy system planners of near 100% renewable power systems conceived within the European National Plans for Energy and Climate [17] are oriented to identify new sources of system inertia (Power system Inertia is the capability of an alternate power system to store kinetic energy in rotating masses-usually from the electric generators/machines directly connected to the grid-that acts to overcome imbalance between power supply and demand, thus being the most important mechanism in the fast frequency regulation of the power system.) [18,19] and novel sources of flexibility [20,21].…”

Review of Dynamic and Transient Modeling of Power Electronic Converters for Converter Dominated Power Systems

“…Since it has become clear that intermittent renewable energy sources will be responsible for a large amount of power generation, the existing methods for power systems reliability assessments will need to be modernized to account for the dynamics of wind, solar, storage, and other grid edge devices [1]. This shift introduces modeling challenges for traditional transient planning and operation and reliability practices [2], [3]. These modeling challenges include the need for electromagnetic transient (EMT) simulations and accurate power electronic converter (PEC) models appropriate for the application of interest.…”

“…Additionally, numerous types of EMT models exist, each appropriate for specific stability issues. Examples of specific stability issues which become present in converter-dominated power systems (CDPS), where converter-based generation exists at both distribution and transmission levels, includes but is not limited to: a high rate of change of frequency due to low inertia [2], [6], [7], limited fault current contribution impacting protection coordination [2], [8]- [10], bi-directional power flow impacting damping of inter-area modes and transient stability margins [11]- [13], harmonic instability due to converter inner control loops [13], [14], interactions between multiple grid-connected converters [13], [15], [16], and lower frequency oscillations introduced by the phase-locked loop (PLL), particularly in weak grids with short circuit ratios less than 2 [13], [17]. An excellent review of these converterbased generation stability issues is provided in [2], [13], [14], [18].…”