scholarly journals Accuracy and Reliability of Switching Transients Measurement with Open-Air Capacitive Sensors

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1405
Author(s):  
Barakou ◽  
Steennis ◽  
Wouters
Keyword(s):  
Electromagnetic Compatibility ◽  
Cross Coupling ◽  
Interference Rejection ◽  
Underground Cables ◽  
Overhead Lines ◽  
Capacitive Divider ◽  
Measurement Methodology ◽  
Extra High Voltage ◽  
Transient Voltages ◽  
Line Coupling

Contactless capacitive (open-air) sensors are applied to monitor overvoltages near overhead line terminations at a substation or at the transition from underground cables to overhead lines. It is shown that these sensors, applied in a differentiating/integrating measuring concept, can result in excellent characteristics in terms of electromagnetic compatibility. The inherent cross-coupling from open-air sensors to other phases is dealt with. The paper describes a method to calibrate the sensor to line coupling matrix based on assumed 50 Hz symmetric phase voltages and in particular focuses on uncertainty analysis of assumptions made. Network simulation shows that predicted maximum overvoltages agree within typically 7% compared to reconstructed values from measurement, also with significant cross-coupling. Transient voltages from energization of an (extra-)high voltage connection can cause large and steep rising ground currents near the line terminations. Comparison with results obtained by a capacitive divider confirms the intrinsic capability in interference rejection by the differentiating/integrating measurement methodology.

scholarly journals Issues and Challenges for HVDC Extruded Cable Systems

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4504
Author(s):  
Giovanni Mazzanti
Keyword(s):  
Renewable Energy Sources ◽  
Alphabetical Order ◽  
Underground Cables ◽  
Overhead Lines ◽  
Available Energy ◽  
Exponential Increase ◽  
Cable Systems ◽  
The Will ◽  
Cross Country ◽  
Transient Voltages

The improved features of AC/DC converters, the need to enhance cross-country interconnections, the will to make massive remote renewable energy sources available, and the fear of populations about overhead lines have fostered HVDC cable transmission all over the world, leading in the last two decades to an exponential increase of commissioned HVDC cable projects, particularly of the extruded insulation type. Comprehensive surveys of the issues to be faced by HVDC extruded cable systems appeared in the literature some years ago, but they are not so up-to-date, as HVDC extruded cable technology is developing fast. Therefore, the contribution this paper aims at giving is a systematic, comprehensive and updated summary of the main present and future issues and challenges that HVDC cable systems have to face to further improve their performance and competitiveness, so as to meet the growing quest for clean and available energy worldwide. The topics covered in this review–treated in alphabetical order for the reader’s convenience–are accessories, higher voltage and power, laying environment (submarine and underground cables), modeling, multiterminal HVDC, operation and diagnostics, recyclable insulation, space charge behavior, testing, thermal stability, transient voltages.

Critical Infrastructure in Sectoral Planning: The Example of the Development and Expansion of the Extra High Voltage Network in Germany

2017 ◽  
Vol 04 (04) ◽  
pp. 1850001
Author(s):  
Christoph Riegel
Keyword(s):  
Critical Infrastructure ◽  
Power Grids ◽  
Underground Cables ◽  
Overhead Lines ◽  
Political Processes ◽  
Sectoral Planning ◽  
Essential Properties ◽  
Pros And Cons ◽  
Security And Reliability ◽  
Extra High Voltage

The power network is among the most of critical infrastructures. In Germany, multiple circumstances, triggered by social and political processes of decarbonization and nuclear phaseout, require extensive grid expansion activities. The paper analyzes coincidences of security and reliability aspects with transmission infrastructure planning. It explores essential properties that determine the criticality of power grids, examines to what extent security is subject of grid expansion procedures and finally focuses on selected security-related spatial planning issues such as the concentration of infrastructures or the pros and cons of overhead lines vs. underground cables.

scholarly journals Photovoltaic Maximum Penetration Limits on Medium Voltage Overhead and Underground Cable Distribution Feeders: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3843
Author(s):  
Sultan Sh. Alanzi ◽  
Rashad M. Kamel
Keyword(s):  
Power System ◽  
Power Factor ◽  
Distribution System ◽  
Power Flow ◽  
Underground Cables ◽  
Overhead Lines ◽  
Medium Voltage ◽  
Load Power ◽  
Bus Voltage ◽  
Pv Penetration

This paper investigates the maximum photovoltaic (PV) penetration limits on both overhead lines and underground cables medium voltage radial distribution system. The maximum PV penetration limit is estimated considering both bus voltage limit (1.05 p.u.) and feeder current ampacity (1 p.u.). All factors affect the max PV penetration limit are investigated in detail. Substation voltage, load percentage, load power factor, and power system frequency (50 Hz or 60 Hz) are analyzed. The maximum PV penetration limit associated with overhead lines is usually higher than the value associated with the underground cables for high substation voltage (substation voltage = 1.05 and 1.04 p.u.). The maximum PV penetration limit decreases dramatically with low load percentage for both feeder types but still the overhead lines accept PV plant higher than the underground cables. Conversely, the maximum PV penetration increases with load power factor decreasing and the overhead lines capability for hosting PV plant remains higher than the capability of the underground cables. This paper proved that the capability of the 60-Hz power system for hosting the PV plant is higher than the capability of 50 Hz power system. MATLAB software has been employed to obtain all results in this paper. The Newton-Raphson iterative method was the used method to solve the power flow of the investigated systems.

scholarly journals An Effective Method to Calculate Frequency Response of Distribution Networks for PLC Applications

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 649 ◽  
Author(s):  
Hongshan Zhao ◽  
Weitao Zhang ◽  
Yan Wang
Keyword(s):  
Frequency Response ◽  
Distribution Networks ◽  
Dynamic Changes ◽  
Binary Function ◽  
Underground Cables ◽  
Overhead Lines ◽  
Medium Voltage ◽  
Response Characteristics ◽  
Network Topologies ◽  
Propagation Matrix

Modelling and estimating power-line communication (PLC) channels are complicated issues due to the complex network topologies, various junctions, and changeable loads. This paper focuses on the frequency response characteristics (FRCs) of medium-voltage (MV) PLC networks with special consideration of two scenarios that are often neglected but generally exist. In the first scenario, the MV distribution network is of the ring topology. In the second scenario, the MV overhead lines and underground cables join at junctions, and the shields of underground cables are grounded with nonzero grounding impedances at the junctions. These conditions lead to the failure of currently popular methods to different degrees. For this reason, we developed an effective method to calculate the FRCs of distribution networks for PLC applications. With this method, the frequency responses of nodes are simply expressed as the binary function of the overall tube propagation matrix and overall node scattering matrix, which is convenient for calculations and analyses. The proposed method was validated by the agreement between the calculated and measured FRCs. The results of two test examples showed that the proposed method performed better in comparison with the traditional approximate method when nonideal grounding conditions were taken into account. The proposed method is also independent of the network topology, so it can adapt to the dynamic changes of the network structure.

scholarly journals Reliability cost/worth assessment of distribution network formed by underground cables and overhead lines. Case study of Latvia

Energetika ◽  
2015 ◽  
Vol 61 (1) ◽  
Author(s):  
Aleksandrs Ļvovs ◽  
Ilze Priedite
Keyword(s):  
Power Supply ◽  
Distribution Network ◽  
Distribution Networks ◽  
Actual Distribution ◽  
Underground Cables ◽  
Overhead Lines ◽  
Capital Costs ◽  
Reliability Level ◽  
Fault Statistics

The increasing number of severe weather occurrences that influence the number of large scale outages, especially in rural distribution networks, makes the question on the need of increasing reliability level of power supply of the distribution network even more actual. Distribution system operators and national regulators shall not only find a reliable but also a cost-effective solution for further distribution network development: the optimal reliability level of power supply. One of the reliability improvement solutions that allows effectively dealing with the reduction of the number of outages in rural distribution networks is the cablification of network. Construction costs of the aforementioned solution are quite high in comparison to other network line types, and due to that, the implementation of the solution always raises discussions on cost-effectiveness. The paper presents approaches for the cost/worth assessment of power line lifetime costs in the distribution network and for the assessment of customer costs of reliability that takes into account time-varying loads and outage costs (previously developed by authors of this paper [6, 7]) as well as for the assessment of traders’ losses due to electrical energy not supplied. The case study included in the paper is performed for Latvian conditions and takes into account information on the real customer costs of reliability of Latvian customers (information from the study of the Institute of Physical Energetics), fault statistics of Latvian underground cables and overhead lines, information with a high level of details on the capital costs, operational and fault elimination costs of distribution lines in Latvia.

Analysis of Capacitive and Inductive Coupling inside Hybrid Integrated Power Electronic Module

2004 ◽  
Vol 1 (3) ◽  
pp. 169-175
Author(s):  
Xiang-jun Zeng ◽  
Xu Yang ◽  
Zhao-an Wang Xi'an
Keyword(s):  
High Frequency ◽  
Electromagnetic Compatibility ◽  
Cross Coupling ◽  
Mutual Inductance ◽  
Image Method ◽  
Power Electronic ◽  
Circulating Current ◽  
Bridge Circuits ◽  
Partial Element Equivalent Circuit ◽  
Driving Circuit

Electromagnetic compatibility has to be given enough attention in the design of hybrid Integrated Power Electronic Module (IPEM) due to the sharply decreased distances between power devices and the control/driving circuits as compared to such distances for conventional power electronic equipment built with discrete devices. The high dν/dt, di/dt and high frequency parasitic ringing emanating from the switching circuit can cause serious EMI within the control/driving circuit due to cross-coupling. This paper analyzes the capacitive and inductive cross-coupling problems inside an IPEM. Finite Element Method (FEM) is used to extract the mutual capacitances between the metal bars in the model. Then the influence of dν/dt can be estimated. The high frequency circulating current in the bridge circuits is also investigated since it causes magnetic interference due to mutual inductance coupling. The mutual inductance is calculated with the simplified Partial Element Equivalent Circuit (PEEC) approach and image method. The experiment validates the effectiveness of this evaluation. In the end, the electromagnetic shielding is discussed.

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