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Control strategy for current limitation and maximum capacity utilization of grid connected PV inverter under unbalanced grid conditions

Joshi J, Jately V, Kala P, Sharma A, Lim WH, Azzopardi B

Sci Rep, 2024 May 02;14(1):10118.
PMID: 38698069 DOI: 10.1038/s41598-024-60244-x

Under grid voltage sags, over current protection and exploiting the maximum capacity of the inverter are the two main goals of grid-connected PV inverters. To facilitate low-voltage ride-through (LVRT), it is imperative to ensure that inverter currents are sinusoidal and remain within permissible limits throughout the inverter operation. An improved LVRT control strategy for a two-stage three-phase grid-connected PV system is presented here to address these challenges. To provide over current limitation as well as to ensure maximum exploitation of the inverter capacity, a control strategy is proposed, and performance the strategy is evaluated based on the three generation scenarios on a 2-kW grid connected PV system. An active power curtailment (APC) loop is activated only in high power generation scenario to limit the current's amplitude below the inverter's rated current. The superior performance of the proposed strategy is established by comparison with two recent LVRT control strategies. The proposed method not only injects necessary active and reactive power but also minimizes overcurrent with increased exploitation of the inverter's capacity under unbalanced grid voltage sag.
1-year results after PCI with the COMBO stent in all-comers in Asia versus Europe: Geographical insights from the COMBO collaboration

Chandrasekhar J, Kalkman DN, Aquino MB, Sartori S, Hájek P, Atzev B, et al.

Int J Cardiol, 2020 05 15;307:17-23.
PMID: 32111358 DOI: 10.1016/j.ijcard.2020.01.045

BACKGROUND: The COMBO drug-eluting stent combines sirolimus-elution from a biodegradable polymer with an anti-CD34+ antibody coating for early endothelialization.
OBJECTIVE: We investigated for geographical differences in outcomes after percutaneous coronary intervention (PCI) with the COMBO stent among Asians and Europeans.
METHODS: The COMBO Collaboration is a pooled patient-level analysis of the MASCOT and REMEDEE registries of all-comers undergoing attempted COMBO stent PCI. The primary outcome was 1-year target lesion failure (TLF), composite of cardiac death, target vessel myocardial infarction (TV-MI) and target lesion revascularization (TLR).
RESULTS: This study included 604 Asians (17.9%) and 2775 Europeans (82.1%). Asians were younger and included fewer females, with a higher prevalence of diabetes mellitus but lower prevalence of other comorbidities than Europeans. Asians had a higher prevalence of ACC/AHA C type lesions and received longer stent lengths. More Asians than Europeans were discharged on clopidogrel (86.5% vs 62.8%) rather than potent P2Y12 inhibitors. One-year TLF occurred in 4.0% Asians and 4.1% of Europeans, p = 0.93. The incidence of cardiac death was higher in Asians (2.8% vs. 1.3%, p = 0.007) with similar rates of TV-MI (1.5% vs. 1.2%, p = 0.54) and definite stent thrombosis (0.3% vs. 0.5%, p = 0.84) and lower incidence of TLR than Europeans (1.0% vs. 2.5%, p = 0.025). After adjustment, differences for cardiac death and TLR were no longer significant.
CONCLUSIONS: In the COMBO collaboration, although 1-year TLF was similar regardless of geography, Asians experienced higher rates of cardiac death and lower TLR than Europeans, while incidence of TV-MI and ST was similar in both regions. Adjusted differences did not reach statistical significance. CLINICALTRIAL.
GOV IDENTIFIER-NUMBERS: NCT01874002 (REMEDEE Registry), NCT02183454 (MASCOT registry).
Comparison of One-Year Outcomes in Patients >75 Versus ≤75 Years With Coronary Artery Disease Treated With COMBO Stents (From The MASCOT Registry)

Chandrasekhar J, Sartori S, Aquino MB, Baber U, Hájek P, Atzev B, et al.

Am J Cardiol, 2020 07 15;127:1-8.
PMID: 32418717 DOI: 10.1016/j.amjcard.2020.04.014

Older patients who undergo coronary interventions are at greater risk of ischemic events and less likely to tolerate prolonged dual antiplatelet therapy (DAPT) due to bleeding risk. The COMBO biodegradable polymer sirolimus-eluting stent promotes rapid endothelialization through endothelial progenitor cell capture technology which may be advantageous in elderly patients. We compared 1-year clinical outcomes and DAPT cessation events in patients >75 versus ≤75 years from the MASCOT registry. MASCOT was a prospective, multicenter cohort study of all-comers undergoing attempted COMBO stenting. The primary endpoint was 1-year target lesion failure (TLF), composite of cardiac death, myocardial infarction (MI) not clearly attributed to a nontarget vessel or clinically driven target lesion revascularization. Bleeding was adjudicated using the Bleeding Academic Research Consortium criteria. Adjusted outcomes were analyzed using Cox regression methods. The study included 18% (n = 479) patients >75 years and 72% (n = 2,135) patients ≤75 years. One-year TLF occurred in 4.6% patients >75 years versus 3.1% patients ≤75years of age, p = 0.10; adj hazard ratio 1.36, 95% confidence intervals 0.77 to 2.38, p = 0.29. There were no significant differences in cardiac death (1.7% vs 1.3%, p = 0.55), MI (2.1% vs 1.2%, p = 0.14), target lesion revascularization (1.7% vs 1.4%, p = 0.60) and definite stent thrombosis (0.8% vs 0.4%, p = 0.19). Major Bleeding Academic Research Consortium 3,5 bleeding (3.1% vs 1.5%, p = 0.01) and DAPT cessation rates (32.4% vs 23.0%, p <0.001) were significantly higher in elderly patients. In conclusion, elderly patients >75 years treated with COMBO stents had similar TLF but significantly greater incidence of bleeding than younger patients and DAPT cessation in one-third of patients over 1 year.
Fulltext 1-Year COMBO stent outcomes stratified by the PARIS bleeding prediction score: From the MASCOT registry

Chandrasekhar J, Baber U, Sartori S, Aquino MB, Hájek P, Atzev B, et al.

Int J Cardiol Heart Vasc, 2020 Dec;31:100605.
PMID: 32953969 DOI: 10.1016/j.ijcha.2020.100605

Background: The COMBO stent is a biodegradable-polymer sirolimus-eluting stent with endothelial progenitor cell capture technology for faster endothelialization.
Objective: We analyzed COMBO stent outcomes in relation to bleeding risk using the PARIS bleeding score.
Methods: MASCOT was an international registry of all-comers undergoing attempted COMBO stent implantation. We stratified patients as low bleeding-risk (LBR) for PARIS score ≤ 3 and intermediate-to-high (IHBR) for score > 3 based on baseline age, body mass index, anemia, current smoking, chronic kidney disease and need for triple therapy. Primary endpoint was 1-year target lesion failure (TLF), composite of cardiac death, myocardial infarction (MI) not clearly attributed to a non-target vessel or clinically-driven target lesion revascularization (TLR). Bleeding was adjudicated using the Bleeding Academic Research Consortium (BARC) definition. Dual antiplatelet therapy (DAPT) cessation was independently adjudicated.
Results: The study included 56% (n = 1270) LBR and 44% (n = 1009) IHBR patients. Incidence of 1-year TLF was higher in IHBR patients (4.1% vs. 2.6%, p = 0.047) driven by cardiac death (1.7% vs. 0.7%, p = 0.029) with similar rates of MI (1.8% vs. 1.1%, p = 0.17), TLR (1.5% vs. 1.6%, p = 0.89) and definite/ probable stent thrombosis (1.2% vs. 0.6%, p = 0.16). Incidence of 1-year major BARC 3 or 5 bleeding was significantly higher in IHBR patients (2.3% vs. 0.9%, p = 0.0094), as was the incidence of DAPT cessation (29.3% vs. 22.8%, p