On-site low voltage determination of zero sequence impedances for station auxiliary transformers

2016 ◽  
Author(s):  
Mariana Kamel ◽  
Haytham Saeed ◽  
Abdelrahman Karrar ◽  
Ahmed Eltom ◽  
Mark Bowman ◽  
...  
Keyword(s):  
Low Voltage ◽  
Zero Sequence

On-Site Low Voltage Determination of Zero-Sequence Impedances for Power Transformers

2020 ◽  
Vol 35 (2) ◽  
pp. 1048-1057
Author(s):  
Haytham Saeed ◽  
Mariana Kamel ◽  
Abdelrahman Karrar ◽  
Ahmed H. Eltom ◽  
Mark Bowman
Keyword(s):  
Low Voltage ◽  
Power Transformers ◽  
Zero Sequence

scholarly journals DETERMINATION OF OPTIMAL CHARACTERISTICS OF DEVICES FOR VOLTAGE UNBALANCE REDUCING IN LOW VOLTAGE ELECTRIC NETWORKS

2020 ◽  
Vol 2020 (6) ◽  
pp. 43-46
Author(s):  
A.F. Zharkin ◽  
◽  
S.O. Palachov ◽  
A.G. Pazieiev ◽  
D.O. Malakhatka ◽  
...  
Keyword(s):  
Simulation Modeling ◽  
Low Voltage ◽  
Electric Energy ◽  
Electrical Safety ◽  
Electric Networks ◽  
Voltage Unbalance ◽  
Zero Sequence ◽  
Unbalanced Loads

Ways of searching for optimal ways to improve the quality of electric energy in electric networks with dispersed unbalanced loads using zero-sequence current filters are considered, which take into account the possibility of ensuring the desired performance with minimal cost and taking into account the peculiarities of operation in emergency network conditions and ensuring electrical safety of consumers. Corresponding calculations were carried out using simulation modeling. References 6, figures 4.

scholarly journals Calculations, norming and reducing of electrical energy losses in city electrical networks

2019 ◽  
Vol 21 (3) ◽  
pp. 46-54
Author(s):  
A. V. Lykin ◽  
E. A. Utkin
Keyword(s):  
High Voltage ◽  
Power Transmission ◽  
Low Voltage ◽  
Demand Curve ◽  
Electrical Energy ◽  
Electrical Network ◽  
Energy Losses ◽  
Capital Investments ◽  
Electrical Networks

The article considers the feasibility of changing the structure of a distribution electrical network by transferring points of electricity transformation as close to consumers as possible. This approach is based on installation of pole-mounted transformer substations (PMTS) near consumer groups and changes the topology of the electrical network. At the same time, for groups of consumers, the configuration of sections of the low-voltage network, including service drops, changes. The efficiency of approaching transformer substations to consumers was estimated by the reduction in electrical energy losses due to the expansion of the high-voltage network. The calculation of electrical losses was carried out according to twenty-four hour consumer demand curve. To estimate the power losses in each section of the electrical network of high and low voltage, the calculated expressions were obtained. For the considered example, the electrical energy losses in the whole network with a modified topology is reduced by about two times, while in a high-voltage network with the same transmitted power, the losses are reduced to a practically insignificant level, and in installed PMTS transformers they increase mainly due to the rise in total idle losses. The payback period of additional capital investments in option with modified topology will be significantly greater if payback is assessed only by saving losses cost. Consequently, the determination of the feasibility of applying this approach should be carried out taking into account such factors as increasing the reliability of electricity supply, improving the quality of electricity, and increasing the power transmission capacity of the main part of electrical network.

Determination of the future actuator demand of adaptive smart low voltage grids

2017 ◽  
Author(s):  
Philippe Steinbusch ◽  
Jan Meese ◽  
Roman Uhlig ◽  
Jan Mehlich ◽  
Marcus Stotzel ◽  
...  
Keyword(s):  
Low Voltage ◽  
The Future

scholarly journals Analysis of Effective Three-Level Neutral Point Clamped Converter System for the Bipolar LVDC Distribution

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 691 ◽  
Author(s):  
Ju-Yong Kim ◽  
Ho-Sung Kim ◽  
Ju-Won Baek ◽  
Dong-Keun Jeong
Keyword(s):  
Distribution System ◽  
Low Voltage ◽  
Balance Control ◽  
Short Circuit ◽  
Renewable Energy Sources ◽  
Neutral Point ◽  
Extreme Load ◽  
Zero Sequence ◽  
Zero Sequence Voltage ◽  
Short Circuit Condition

Low-voltage direct current (LVDC) distribution has attracted attention due to increased DC loads, the popularization of electric vehicles, energy storage systems (ESS), and renewable energy sources such as photovoltaic (PV). This paper studies a ±750 V bipolar DC distribution system and applies a 3-level neutral-point clamped (NPC) AC/DC converter for LVDC distribution. However, the 3-level NPC converter is fundamental in the neutral-point (NP) imbalance problem. This paper discusses the NP balance control method using zero-sequence voltage among various solutions to solve NP imbalance. However, since the zero-sequence voltage for NP balance control is limited, the NP voltage cannot be controlled to be balanced when extreme load differences occur. To maintain microgrid stability with bipolar LVDC distribution, it is necessary to control the NP voltage balance, even in an imbalance of extreme load. In addition, due to the bipolar LVDC distribution, the pole where a short-circuit condition occurs limits the short current until the circuit breaker operates, and a pole without a short-circuit condition must supply a stable voltage. Since the conventional 3-level NPC AC/DC converter alone cannot satisfy both functions, an additional DC/DC converter is proposed, analyzed, and verified. This paper is about a 3-level NPC AC/DC converter system for LVDC distribution. It can be used for the imbalance and short-circuit condition in bipolar LVDC distribution through the prototype of the 300 kW 3-level NPC AC/DC converter system and experimented and verified in various conditions.

scholarly journals The influence of the network asymmetry on the settings and sensitivity of an earth fault protection using higher harmonics

2019 ◽  
Vol 84 ◽  
pp. 02008
Author(s):  
Lubomir Marciniak ◽  
Mateusz Piątek
Keyword(s):  
Reactive Power ◽  
Higher Harmonics ◽  
Medium Voltage ◽  
Earth Fault ◽  
Power Setting ◽  
Zero Sequence ◽  
The Asymmetry ◽  
Supply Voltages ◽  
Zero Sequence Voltage

Detection of high resistance earth faults in medium voltage networks is an important problem due to ineffectiveness of traditional earth fault protections. Such short circuits can be detected by the criterion of a reactive power of higher harmonics for zero sequence current and voltage. The main problem is determination of the power setting value in the protection, which depends on the asymmetry of phase-to-earth capacitances and higher harmonics in supply voltages, which are generated by non-linear loads. The intensive tests of the asymmetry of the zero sequence currents and voltages for harmonics and their reactive power have been carried out in 15 kV compensated network as a function of all relevant parameters, i.e.: maximum capacitance deviation of the network and protected line, percentage content of harmonics in supply voltages, capacitive current of the network and the line. It has been shown that third harmonics of the zero sequence voltage and current are the best suited for practical use, since the asymmetry reactive power of these components is the smallest among the considered harmonics and the protection sensitivity will be the highest.

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