An alternative approach to provisions of the Network Code on blocking HVDC LCC systems during short-circuits in AC network

The Network Code for HVDC systems introduces a requirement for such systems to remain in operation in an AC network during short-circuits. This requirement (among others) is determined by a time curve of a minimum voltage in HVDC connection point. The HVDC system is not allowed to be turned-off while the voltage value exceeds the values of the curve, however the HVDC system in LCC technology does not meet this requirement. The Network Code introduces the possibility of blocking the LCC systems. After the LCC system is blocked it stops transmitting the power, which prevents the LCC system from being turned off during a short-circuit in the network but results in a lack of power exchange between the network and the LCC system. Therefore, the authors developed a proposal to limit the power level being transmitted by the LCC system, thus there is no necessity to block the LCC system operation. The simulation research carried out clearly indicate the validity of this idea. In addition, the authors presented the concept of an automation system that adaptively adjusts the scale of the LCC system power level reduction to change the network operating conditions during a short-circuit in the network. The operation of this automation system is presented for the practical LCC system model installed in the Polish Power System

The idea of non-restricted use of LV networks by electricity consumers, producers, and prosumers

Until now, electricity users are being connected to the LV networks by a physical electricity consumption point. In this point an electricity meter is assigned to each and every one user. A given user may use the flowing electricity only by the meter assigned to him at the consumer-specific point. This is a significant limitation in the non- restricted access to the power network. The Authors come with an idea to eliminate this restriction. The paper presents the concept of virtualization of a physical point of electric power consumption in a LV network. The proposed novel idea of using the power network will ensure the expected non-restricted access to any point of the power network for users. This seems particularly important nowadays and is dictated by the growing expectations of users’ mobility. The presented concept is dedicated especially to networks in the form of clusters (cooperatives) or energy clouds. Its application in LV networks will significantly simplify the users’ use of the power infrastructure, also in the aspect of financial settlements. This should also contribute to the rapid significant development of electro- mobility

Analysis of operations for line distance protection in power networks with LCC-HVDC systems

Układy HVDC znajdują coraz szersze zastosowanie w elektroenergetyce, m.in. jako elementy wymiany mocy między układami sieciowymi pracującymi niesynchronicznie lub elementy wyprowadzenia mocy z parków energii z podłączeniem prądu stałego. Jednak dotychczas często stosowana w nich technologia LCC wykazuje dużą podatność na przewroty komutacyjne. Towarzyszą im gwałtowne zmiany napięć i prądów w otoczeniu układu HVDC. Może to prowadzić m.in. do niepoprawnego działania zabezpieczeń odległościowych linii i stanowić zagrożenie dla bezpiecznej pracy sieci i jej użytkowników. Publikacja zawiera wyniki oceny możliwego negatywnego oddziaływania układów HVDC LCC na te podstawowe zabezpieczenia linii NN i WN. Taka ocena jest szczególnie istotna obecnie, w perspektywie wielu zapowiadanych inwestycji w układy HVDC.High Voltage Direct Current (HVDC) systems are increasingly used in power networks. However, usually used in them LCC (Line Commutated Converters) technology causes high susceptibility to commutation failures. Significant changes in network operation conditions accompany this phenomenon. This is manifested, among others violent and significant changes in the values of voltages and currents in the vicinity of the HVDC system. These voltages and current are used by distance protection lines to identify the actual state of the line. This causes that commutation failures in the HVDC system may lead to incorrect operation of distance protection line and unjustified switching off the line or lack of required line shutdown. Incorrect operation of the distance protection may be dangerous for the safe operation of the line, other power network objects and electricity consumers. The paper shows the recognition and accurate characterization of potential scale of abnormalities in the operation of distance protection lines, which work in the vicinity of the HVDC systems. It is emphasized that the subject of the paper is particularly important now. This is dictated by the multitude of announced investments in HVDC systems, primarily as a component of strongly promoted off-shore energy parks

The concept of area measurement algorithm of line distance protection for single-phase faults

Klasyczne zabezpieczenia odległościowe, obecnie stosowane w liniach WN i NN, identyfikują stan pracy chronionej linii, kontrolując parametry impedancji pętli zwarcia. Powoduje to dużą wrażliwość poprawności ich działania na czynniki fałszujące „pomiar” impedancji. Jest to podyktowane wyznaczaniem impedancji wyłącznie na podstawie sygnałów napięciowych i prądowych dostępnych lokalnie, w miejscu zainstalowania zabezpieczenia. Dotyczy to zarówno zwarć wielofazowych, jak i jednofazowych. Dla zwarć wielofazowych autorzy opracowali koncepcję nowych algorytmów wyznaczania impedancji, dla których wykazano niewrażliwość na czynniki fałszujące występujące w zabezpieczeniach klasycznych. W publikacji przedstawiono koncepcję tożsamego algorytmu dedykowanego dla zwarć jednofazowych. Zamieszczono także wyniki badań symulacyjnych dowodzących poprawności tego algorytmu.Classic line distance protection, previously used in high and extra high voltage, are sensitive to factors falsifying the measurement of impedance (among others: non-zero fault resistance, fault leakage current phenomenon, passive and active outflow of the power line). This determines the high risk of incorrect operation of these protections. As a result, this may lead to unwanted switching off the line which work normal network conditions or the lack of the required shutdown the line affected by the fault. The main cause of incorrect operation of the power line protection is identification of the line operation status based on the impedance determined by the measurement algorithm based only on voltage and current signals available locally at the protection location. This applies to phase-to-phase faults and single-phase faults. For phase faults authors have already developed the concept of new measurement algorithms. Simulations and laboratory study have demonstrated the insensitivity of these algorithms to the factors falsifying the operation of classical distance protections. Currently, the authors have defined a similar concept a new measurement algorithm dedicated to single-phase faults. The publication presents equations this new algorithm and the results of simulation verification tests

Supervised Training of Siamese Spiking Neural Networks with Earth Mover's Distance

This study adapts the highly-versatile siamese neural network model to the event data domain. We introduce a supervised training framework for optimizing Earth Mover's Distance (EMD) between spike trains with spiking neural networks (SNN). We train this model on images of the MNIST dataset converted into spiking domain with novel conversion schemes. The quality of the siamese embeddings of input images was evaluated by measuring the classifier performance for different dataset coding types. The models achieved performance similar to existing SNN-based approaches (F1-score of up to 0.9386) while using only about 15% of hidden layer neurons to classify each example. Furthermore, models which did not employ a sparse neural code were about 45% slower than their sparse counterparts. These properties make the model suitable for low energy consumption and low prediction latency applications.Comment: Revised paper accepted for presentation at 2022 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP

Reliable Diagnostics of SARS-CoV-2 Infections Using One- and Two-Gene Molecular Tests for a Viral RNA Detection—Results Questioning Previous Observations

SARS-CoV-2 is a new virus from the Coronaviridae family and its rapid spread is now the most important medical problem worldwide. Currently used tests vary in the number and selection of SARS-CoV-2 target genes. Meanwhile, the choice of the appropriate target gene may be important in terms of a reliable detection of a viral RNA. As some researchers questioned the sensitivity of the monogenic VIASURE SARS-CoV-2 S gene Real Time PCR Detection Kit (CerTest Biotec, Zaragoza, Spain) in mid-2020, the aim of the study was to evaluate the usefulness of this kit, used along with the BD MAX™ System (Becton Dickinson, East Rutherford, NJ, USA), and compare the results with two-gene Bosphore Novel Coronavirus (2019-nCoV) Detection Kit v1 (Anatolia Diagnostics and Biotechnology Products Inc., Istanbul, Turkey). Both tests were carried out on 306 nasopharyngeal/oropharyngeal swabs. The consistent results (72 positive and 225 negative results found simultaneously in both kits) were obtained for 297 (97.1%) samples altogether, while discrepancies between the results of the evaluated tests were observed for nine (2.9%) specimens. There were no statistically significant differences between the method used and the frequency of positive results. Both tests, targeted at detecting one and two genes, are effective in SARS-CoV-2 RNA detection

Analysis of power system protection against hight-current fault operation in working island of the power grid mining plant

W artykule przedstawiono wyniki badań analitycznych weryfikujących poprawność działania zabezpieczeń od skutków zwarć wielkoprądowych we fragmencie sieci elektroenergetycznej zakładu górniczego pracującym jako wyspa sieciowa. Warunki prądowe towarzyszące zwarciom wielkoprądowym w układach pracy wyspowej silnie zależą od zdolności lokalnej jednostki wytwórczej energii elektrycznej do generacji prądu zwarciowego. Zwykle w przypadku przejścia fragmentu sieci do pracy wyspowej występuje znaczne zmniejszenie poziomu mocy zwarciowej, co w efekcie doprowadzi do ograniczenia poziomu prądów zwarć wielkoprądowch.The safe operation of a mining plant requires continuous supply of the most important loads. In catastrophic situations, power supply from the power system side may be interrupted, eg. due to break of overhead power lines supplying the plant. Therefore, the supply of selected critical devices of a mining plant from a local generating unit (operating within this plant) can significantly improve the safety of the mining plant operations. However, the implementation of this task requires separating a fragment of the mining plant network and its transition to island operation. The implementation of such a state requires, among others, carrying out verification of the correct operation of electrical power protection systems. The paper presents analysis of power system protection against hight–current fault operation of the power grid mine working island. Current conditions accompanying high-currents faults in island systems are strongly dependent on the ability of the local electricity generation unit to generate short-circuit current. Usually in case of electricity power network transition to island operation, there is a significant reduction in the level of high–current fault, what may cause a bad operation of power system protection

An alternative approach to provisions of the Network Code on blocking HVDC LCC systems during short-circuits in AC network

The Network Code for HVDC systems introduces a requirement for such systems to remain in operation in an AC network during short-circuits. This requirement (among others) is determined by a time curve of a minimum voltage in HVDC connection point. The HVDC system is not allowed to be turned-off while the voltage value exceeds the values of the curve, however the HVDC system in LCC technology does not meet this requirement. The Network Code introduces the possibility of blocking the LCC systems. After the LCC system is blocked it stops transmitting the power, which prevents the LCC system from being turned off during a short-circuit in the network but results in a lack of power exchange between the network and the LCC system. Therefore, the authors developed a proposal to limit the power level being transmitted by the LCC system, thus there is no necessity to block the LCC system operation. The simulation research carried out clearly indicate the validity of this idea. In addition, the authors presented the concept of an automation system that adaptively adjusts the scale of the LCC system power level reduction to change the network operating conditions during a short-circuit in the network. The operation of this automation system is presented for the practical LCC system model installed in the Polish Power System

The idea of non-restricted use of LV networks by electricity consumers, producers, and prosumers

Until now, electricity users are being connected to the LV networks by a physical electricity consumption point. In this point an electricity meter is assigned to each and every one user. A given user may use the flowing electricity only by the meter assigned to him at the consumer-specific point. This is a significant limitation in the non- restricted access to the power network. The Authors come with an idea to eliminate this restriction. The paper presents the concept of virtualization of a physical point of electric power consumption in a LV network. The proposed novel idea of using the power network will ensure the expected non-restricted access to any point of the power network for users. This seems particularly important nowadays and is dictated by the growing expectations of users’ mobility. The presented concept is dedicated especially to networks in the form of clusters (cooperatives) or energy clouds. Its application in LV networks will significantly simplify the users’ use of the power infrastructure, also in the aspect of financial settlements. This should also contribute to the rapid significant development of electro- mobility