Computational planning of the synthesis of complex natural products

Training algorithms to computationally plan multistep organic syntheses has been a challenge for more than 50 years(1-7). However, the field has progressed greatly since the development of early programs such as LHASA(1,7), for which reaction choices at each step were made by human operators. Multiple software platforms(6,8-14) are now capable of completely autonomous planning. But these programs 'think' only one step at a time and have so far been limited to relatively simple targets, the syntheses of which could arguably be designed by human chemists within minutes, without the help of a computer. Furthermore, no algorithm has yet been able to design plausible routes to complex natural products, for which much more far-sighted, multistep planning is necessary(15,16) and closely related literature precedents cannot be relied on. Here we demonstrate that such computational synthesis planning is possible, provided that the program's knowledge of organic chemistry and data-based artificial intelligence routines are augmented with causal relationships(17,18), allowing it to 'strategize' over multiple synthetic steps. Using a Turing-like test administered to synthesis experts, we show that the routes designed by such a program are largely indistinguishable from those designed by humans. We also successfully validated three computer-designed syntheses of natural products in the laboratory. Taken together, these results indicate that expert-level automated synthetic planning is feasible, pending continued improvements to the reaction knowledge base and further code optimization. A synthetic route-planning algorithm, augmented with causal relationships that allow it to strategize over multiple steps, can design complex natural-product syntheses that are indistinguishable from those designed by human experts

Performance analysis of power swing blocking feature in ABB 670 series impedance relays

This paper presents test results of a distance protection’s PSD power swing detection feature in ABB 670 series relays. A RED670 relay was tested, which is part of the hydroelectric set protection in Żarnowiec Pumped Storage Plant. The power swing blocking feature’s performance was analysed on the basis of the results of object tests made with an Omicron digital tester. Also presented are simulation results that illustrate the PSD feature’s response to power swings caused by a disturbance in the power system. It is also shown how a distance protection may react to the same fault, depending on its settings

Earth wires currents calculation in UGC-OHL lines

W referacie analizowana jest linia napowietrznokablowa 110 kV. Referat prezentuje wpływ sposobu uziemiania żył powrotnych kabla WN na wartości prądów przy zwarciach jednofazowych, ze szczególnym uwzględnieniem prądów płynących w przewodach odgromowych linii napowietrznej. Wykazano, że dobór przewodów odgromowych linii napowietrznej powinien uwzględniać nie tylko parametry odcinka linii kablowej, ale także sposób uziemienia żył powrotnych.The high voltage overhead (OHL) and underground cable line (UGC) is analyzed in the paper. The paper presents the influence of the cable sheath earthing on the values of currents in case of earth faults, with particular focus on the currents flowing in the earth wires. It is shown that the selection of the earth wires for the overhead line should take into account not only the parameters of the cable line section, but also the method of the cable sheath earthing. The single point earthing with no earth continuity conductor (ECC) is particularly not recommended, because it leads to the earth wire currents and earth potential rise

A Paradigm for HV, MV, LV Distribution Grid Development Planning

In the literature, including that relating to businesses in the energy (and power) sector, the concept of these organizations’ operating paradigm may be found. The paper discusses the concept of the paradigm, with a focus on the power grid development planning paradigm. Against this background, issues related to energy security and power systems development trends and problems are presented. A new paradigm is proposed for distribution grid development planning. This paradigm is an original proposal of the authors

Wpływ mikroźródeł na odkształcenia napięcia w sieci elektroenergetycznej

The increase in the number of photovoltaic (PV) systems integrated with low voltage (LV) grids has led to a great need to analyse the impact of these systems on the quality of electricity and the reliability of its supply. This paper presents and compares the energy quality requirements imposed by various countries on photovoltaic plants. Then, based on real object tests and simulation in DIgSILENT PowerFactory, the impact has been identified of insolation on the generation output, range of harmonic emissions, changes in voltage levels, and total harmonic distortion (THD) in current and voltage. The results depended on the micro-source power and location, and the grid load.Wzrost liczby systemów fotowoltaicznych (PV) zintegrowanych z sieciami niskiego napięcia (nn) spowodował ogromną potrzebę analizy wpływu tych systemów na jakość energii elektrycznej i niezawodność jej dostaw. W artykule przedstawiono i porównano wymogi jakości energii, jakie różne kraje nakładają na instalacje fotowoltaiczne. Następnie na podstawie przeprowadzonych badań na rzeczywistym obiekcie i symulacji w programie DIgSILENT PowerFactory określono m.in. wpływ nasłonecznienia na generację, zasięg emisji harmonicznych, zmiany poziomów napięcia, współczynnik całkowitej zawartości harmonicznych (THD) w prądzie i napięciu. Wyniki uzależniono od mocy mikroźródła, jego umiejscowienia oraz od obciążenia sieci

Start-up of a power unit of a thermal power plant auxiliary system with supply from a hydropower plant

This article discusses the issues related to a power unit of a thermal power plant start-up with the use of a hydropower plant. Hydropower plant can supply and will enable start-up of auxiliary equipment in a power unit of a thermal power plant. Due to high capacity of auxiliary drives, startup of auxiliaries in a thermal power plant after blackout (and boiler shutdown) is not possible from emergency energy sources in the power plant. In such a case an external electricity source with high capacity is required

The Issues of Reactive Power Compensation in High-voltage Transmission Lines

This paper discusses the selection of compensation shunt reactors for a double-circuit 400 kV transmission line using the example of the newly built Elk Bis – Alytus transmission line. The analysis takes into account various conditions of the power system. The published results relate to voltage levels in steady states and during switching processes and short circuits

Induced sheath voltages in 110 kV power cables – case study*

This paper considers electric shock hazard due to induced sheath voltages in 110 kV power cables. The purpose of this paper is to find an optimal configuration of the power cable system, taking into account electric shock hazard and ability of the system to transfer maximal power. A computer simulations on a computer model of the local power system, comprising high voltage power cables, were carried out. This model enables to analyse various configurations of the metallic cable sheaths bonding and earthing (single-point bonding, both-ends bonding, cross-bonding) and their impact on induced voltages in the cable sheaths. The analysis presented in the paper shows, that it is possible to find an optimal configuration of the complicated power cable system, in terms of electric shock hazard, maximal power transfer as well as economic aspects

Simplified modeling of high voltage power cables vs. induced sheath voltages – case study

Linie kablowe, obok linii napowietrznych, są jednym z podstawowych elementów składowych systemów elektroenergetycznych. Stosowane są głównie na terenach zurbanizowanych, gdzie prowadzenie linii napowietrznych jest mocno utrudnione lub wręcz niemożliwe. Linie kablowe wysokiego napięcia budowane są głównie z wykorzystaniem kabli, które oprócz żyły roboczej mają również współosiową żyłę powrotną. Istnieje kilka układów pracy takich linii, które różnią się sposobem uziemienia żył powrotnych i ewentualnym zastosowaniem przeplatania żył powrotnych i/lub żył roboczych. Budowa linii kablowej wysokiego napięcia każdorazowo powinna zostać poprzedzona analizą modelową, która pozwoli określić poziomy napięć i prądów indukowanych w żyłach powrotnych. Jak wynika z analiz, zbyt duże uproszczenia w modelowaniu mogą prowadzić do błędnego wnioskowania.The construction of a high voltage cable lines should be preceded by a model analysis, which will allow to determine the levels of voltages and currents induced in their sheaths. In turn, the accuracy of modeling and the simplifications adopted in the model may lead to wrong conclusions

Energetyka odnawialna na potrzeby pokrywania strat w stacji elektroenergetycznej GPZ

According to the Energy Efficiency Act, the burden of searching for solutions to limit losses incurred during the transformation and transmission of electricity also rests with distribution system operators (DSOs). One of the intermediary facilities in the electric power supply chain to consumers is an HV/MV substation, which is characterized by relatively high energy losses. The paper analyses the rationale for the use of renewable energy micro-sources in HV/MV substations to increase the efficiency of their operation and the impact on CO2 reduction.Zgodnie z ustawą o efektywności energetycznej ciężar poszukiwania rozwiązań służących do ograniczania strat ponoszonych podczas transformacji i przesyłu energii elektrycznej spoczywa również na operatorach systemów dystrybucyjnych (OSD). Jednym z obiektów pośredniczących w dostarczaniu energii elektrycznej odbiorcom są stacje elektroenergetyczne WN/SN (główne punkty zasilania, GPZ), które charakteryzują się relatywnie wysokimi stratami energii elektrycznej. W artykule przeanalizowano zasadność zastosowania mikroźródła OZE w stacjach GPZ pod kątem podnoszenia efektywności ich pracy i wpływu na redukcję CO2