Power system protection with digital overcurrent relays: a review of non-standard characteristics

Power systems are experiencing structural changes induced by the integration of distributed generation units and the operation of microgrids. This transformation has posed new challenges in well-established power system practices and especially on the design and coordination of protection systems. At roughly the same time, technological advancements in protective equipment have constituted the basis for the emergence of digital overcurrent relays which enable alternative approaches to standard protection schemes. As a consequence, recent studies aimed to provide a reliable protection system capable of responding to the modern power system conditions by propounding the utilization of non-standard characteristics (N-SCs), as opposed to the standard characteristics, i.e., characteristics that are not described in the currently used standards. Despite the fact that the effects of the aforementioned changes on the protection of power systems have been thoroughly analyzed in the technical literature, the requirements for devising N-SCs have not been discussed in detail so far. To address this gap, this paper classifies and analyzes the related studies with respect to their potential advantages and disadvantages. Moreover, based on the literature review, recommendations for further research in this area and a list of the requirements for devising robust non-standard relay characteristics are presented

Post-COVID-19 vaccination inflammatory syndrome: A case report

A previously healthy 24-year-old male patient was referred to our clinic with bilateral lower extremity pain and dark urine, which were developed 2 weeks after receiving the second dose of the BNT162b2 vaccine against severe acute respiratory coronavirus 2. Laboratory tests indicated rhabdomyolysis. Lower extremity magnetic resonance imaging was compatible with myositis. Myositis-related antibodies were negative. Biopsy taken from gastrocnemius muscle revealed muscle necrosis and striking expression of major histocompatibility complex class I antigen. He was successfully treated, and his complaints were resolved. One week later at follow-up, he reported new-onset exertional dyspnoea with palpitations. ST-segment depressions were spotted on electrocardiography. Troponin T was found elevated as 0.595 ng/ml (normal <0.014 ng/ml). Echocardiography showed a hypokinetic left ventricle with an ejection fraction of 40% and pericardial effusion of 2 mm. An appropriate treatment plan was formulated for the diagnosis of myocarditis, eventually, the patient recovered within 10 days. The BNT162b2 messenger ribonucleic acid (mRNA) vaccine was felt to cause the aforementioned condition since no other aetiology could be identified. Although it is known that BNT162b2 may induce myocarditis, myositis concomitant myocarditis appears to be a very rare adverse effect of this vaccine

A 19-Year-Old Pregnant Woman With Pulmonary Hypertension With Progressive Dyspnea

CASE PRESENTATION: A 19-year-old pregnant woman at week 32 of gestation was referred to our clinic with progressive shortness of breath for the further evaluation and treatment of high-risk pregnancy. Her complaints had been existing since her childhood. Two years prior to her admission, she had been diagnosed with heart failure with preserved ejection fraction due to cardiomyopathy and associated pulmonary hypertension. The patient had no family history of any cardiac disease. She had never smoked or drunk alcohol. Her clinical condition had deteriorated progressively with the pregnancy

Predictors of Complex Aortic Plaques in Patients Undergoing Transoesophageal Echocardiography

Introduction: Atrial fibrillation (AF) is one of the most important causes of ischaemic stroke according to the TOAST classification. The CHA(2)DS(2)-VASc score is a widely used scoring system for estimating systemic thromboembolism in patients with non-valvular AF. TOAST classification indicates that an ischaemic stroke may also be due to large artery atherosclerosis. Since some of the atherosclerotic risk factors also occur in the CHA(2)DS(2)-VASc scoring system, we hypothesised that this scoring system can also predict the presence of complex aortic plaques and their stroke risk

Assessment of atrial electromechanical delay and P wave dispersion in patients with chronic obstructive pulmonary disease

Objective: Chronic obstructive pulmonary disease (COPD) is associated with atrial fibrillation (AF) and reduced forced expiratory volume (FEV1) is an independent predictor for new onset AF. The aims of this study were (1) to analyze the atrial electromechanical delay (AEMD) and P wave dispersion which are two predictors of AF development in patients with COPD and without any cardiovascular disease, and (2) to assess the relationship of those with pulmonary functions as quantified by FEV1 measurements