The increase in penetration levels of inverter-based resources (IBRs) is changing the dynamic performance of power grids of different parts of the world. IBRs are now being more and more integrated into the grid at a single connection point as an IBR plant. Due to the complex nature and dynamicity of each inverter model, it is not realistic to build and analyze full complex models of each inverter in the IBR plant. Moreover, simulating a large plant including detailed models of all the IBRs would require high computing resources as well as a long simulation time. This has been the main issue addressed in the new IEEE Std 2800-2022. This paper proposes a novel approach to model an IBR plant, which can capture the transient nature at the plant level, detailed IBR control at the inverter level, interactions of multiple IBR groups in a plant structure, and a collector system connecting the IBRs to the grid. The IBRs in the plant use a voltage source inverter topology combined with a grid-connected filter. The control structure of the IBR includes a cascaded loop control where an inner current control and outer power control are designed in the dq-reference frame, and a closed-loop phase-locked loop is used for the grid synchronization. The mathematical study is conducted first to develop aggregated plant models considering different operating scenarios of active IBRs in an IBR plant. Then, an electromagnetic transient simulation (EMT) model of the plant is developed to investigate the plant’s dynamic performance under different operating scenarios. The performance of the aggregated plant model is compared with that of a detailed plant model to prove the effectiveness of the proposed strategy. The results show that the aggregated EMT simulation model provides almost the same result as the detailed model from the plant perspective while the running time/computation burden is much lower.
- Award ID(s):
- 1939144
- NSF-PAR ID:
- 10317612
- Date Published:
- Journal Name:
- IEEE Green Technologies Conference (GreenTech)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
-
Distributed generation is gaining greater penetration levels in distribution grids due to government incentives for integrating distributed energy resources (DERs) and DER cost reductions. The frequency response of a grid-connected single inverter changes as other inverters are connected in parallel due to the couplings among grid inductance and/or inverter output filters. The selection of the inverter- or grid-side currents as feedback control signals is then not trivial because each one has tradeoffs. This paper analyses the system stability for multiple parallel- and grid-connected inverters using the inverter- or gridside currents as feedback signals. Modeling of both feedback signals is performed using the current separation technique. Moreover, the stability range for different conditions including active damping is analyzed through the root locus technique. The grid-side current has a wider range of stability, but the inverterside current allows for higher values of the proportional gain near the critical frequency and no extra sensors are needed since measurement of the inverter current is needed for protection in high-power applications.more » « less
-
null (Ed.)Increased capacity associated with renewable energy sources has created a need for improved methods for controlling power flows from inverter-based generation. This research provides a comparative study of finite-control-set model predictive current control (FCS-MPC-based) with respect to conventional proportional-integral-based (PI-based) synchronous current control for a three-phase voltage source inverter (VSI). The inverter is accompanied by an inductive-capacitive-inductive (LCL) filter to attenuate pulse width modulation (PWM) switching harmonics. However, an LCL filter introduces a resonance near to the control stability boundary, giving rise to substantial complexity from a control perspective. In order to avoid potential instability caused by the resonance, active damping can be included in the PI-based current control. Though properly designed active damping can improve inverter stability, in practice the robustness of standard PI control is not attainable due to variability in the grid inductance at the point of common coupling (PCC). This is due to impedance variations causing large shifts in the LCL resonance frequency. Weak grid conditions (i.e., a low short-circuit ratio) and a correspondingly high line impedance are particularly susceptible to LCL induced resonance instabilities. As an approach to operate with grid impedance variations and weak grid conditions, FCS-MPC has the potential to produce superior performance compared to PI-based current control methods. This comparative study indicates that FCS-MPC has improved resonance damping and fast dynamic capability in a system with renewable energy sources under weak grid conditions. Detailed results from MATLAB/SimPower are presented to validate the suggested FCS-MPC method where it is robust to uncertainty in the grid impedance variations. Overall results indicate an improvement over conventional PI-based current control methods.more » « less
-
Abstract The development of next-generation batteries, utilizing electrodes with high capacities and power densities requires a comprehensive understanding and precise control of material interfaces and architectures. Electro-chemo-mechanics plays an integral role in the morphological evolution and stability of such complex interfaces. Volume changes in electrode materials and the chemical interactions of electrode/electrolyte interfaces result in nonuniform stress fields and structurally different interphases, fundamentally affecting the underlying transport and reaction kinetics. The origin of this mechanistic coupling and its implications on degradation is uniquely dependent on the interface characteristics. In this review, the distinct nature of chemo–mechanical coupling and failure mechanisms at solid–liquid interfaces and solid–solid interfaces is analyzed. For lithium metal electrodes, the critical role of surface/microstructural heterogeneities on the solid electrolyte interphase (SEI) stability and dendrite growth in liquid electrolytes, and on the onset of contact loss and filament penetration with solid electrolytes is summarized. With respect to composite electrodes, key differences in the microstructure-coupled electro-chemo-mechanical attributes of intercalation- and conversion-based chemistries are delineated. Moving from liquid to solid electrolytes in such cathodes, we highlight the significant impact of solid–solid point contacts on transport/mechanical response, electrochemical performance, and failure modes such as particle cracking and delamination. Finally, we present our perspective on future research directions and opportunities to address the underlying electro-chemo-mechanical challenges for enabling next-generation lithium metal batteries.more » « less
-
more » « less
Abstract Resilience of ecological systems has been a central focus in aquatic sciences over the last 20 yr and critical to the understanding of ecological dynamics. Here, data from long‐term time series and experimental manipulations are used to examine resilience of two fucoid macroalgae in the Gulf of Maine, USA. Experimental clearings that mimic ice scour of different sizes were established in stands of
Ascophyllum nodosum in the winter of 1996–1997. Half of the clearings were scraped again during winter 2010–2011 to compare trajectories between plots that had been recleared and those that remained intact. Short‐term experiments were done to test hypotheses of inhibition of recruitment and influence of hydrodynamic exposure, clearing size, and consumers as drivers of the observed successional trajectories.A. nodosum was resilient to small clearings within two generation times (15–18 yr), but resilience lessened with increased magnitude of perturbation leaving nearly half of large clearings dominated by another fucoid,Fucus vesiculosus after 25 yr.F. vesiculosus was resilient against invasion byA. nodosum when it recruited early and grew rapidly, dominating space within two to three generation times (~ 3 yr). WhenA. nodosum established a foothold prior to dominance byF. vesiculosus ,F. vesiculosus was a long transient state. Water motion, lack of consumers, and large clearings favor rapid domination byF. vesiculosus , which inhibits establishment ofA. nodosum , thus forming an alternative stable state. ForA. nodosum , its longevity and large biomass per unit area are key toA. nodosum inhibitingF. vesiculosus and forming the other stable state.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/GreenTech48523.2021.00082
