scholarly journals The Short-Circuit Protections in Hybrid Systems with Low-Power Synchronous Generators

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 160
Author(s):  
Bartosz Rozegnał ◽  
Paweł Albrechtowicz ◽  
Dominik Mamcarz ◽  
Natalia Radwan-Pragłowska ◽  
Artur Cebula
Keyword(s):  
Single Phase ◽  
Low Voltage ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Electrical Systems ◽  
Protection Devices ◽  
Short Circuits ◽  
Damage Type

Single-phase short-circuits are most often faults in electrical systems. The analysis of this damage type is taken for backup power supply systems, from small power synchronous generators. For these hybrid installations, there is a need for standard protection devices, such as fuses or miniature circuit breaker (MCB) analysis. Experimental research mentioned that a typical protective apparatus in low-voltage installations, working correctly during supplying from the grid, does not guarantee fast off-switching, while short-circuits occur during supplication from the backup generator set. The analysis of single-phase short-circuits is executed both for current waveform character (including sub-transient and transient states) and the carried energy, to show the problems with the fuses and MCB usage, to protect circuits in installations fed in a hybrid way (from the grid and synchronous generator set).

scholarly journals ANALYSIS OF OVERVOLTAGE POSSIBILITY ON THE EXCITATION WINDING OF A SYNCHRONOUS GENERATOR OF AUTONOMOUS POWER SUPPLY SYSTEM IN CASE OF EXTERNAL SYMMETRICAL SHORT CIRCUIT

2021 ◽  
pp. 112-115
Author(s):  
V.B. Beliy ◽  
Keyword(s):  
Power Systems ◽  
Power Supply ◽  
Short Circuit ◽  
Electric Energy ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Excitation System ◽  
Three Phase ◽  
Short Circuits ◽  
Analytical Expressions

Reliable supply of consumers with electric energy largely depends on the reliability of power source function-ing. In the context of this paper it depends on synchronous generators operating in autonomous power supply sys-tems. In contrast to the power plant generators which are part of power systems and are protected from the loads by sufficiently large resistances, power supply systems withautonomous generators are characterized by rather low resistances. Abrupt changes in the supply load parameters, their own transient and emergency modes, for example, short circuits at the generator terminals, forcing excitation, etc. may lead to various failures in the synchronous gener-ator operation. This paper discusses the possibility of over-voltage in the valve excitation system of a synchronous generator with external three-phase short circuits. On the basis of analytical expressions describing the physical pro-cesses occurring in the excitation system of synchronous generators, the conditions for the occurrence of overvolt-ages are identified

scholarly journals Method of assessment and prediction of overvoltage caused by single-phase arc ground short circuits in the 6–10 kV mains, as a way of increasing the electrical safety level in mining facilities

2020 ◽  
pp. 116-132
Author(s):  
Kuzmin Roman ◽  
◽  
Kuzmin Ilia ◽  
Menshikov Vitalii ◽  
Kuzmin Sergei ◽  
...  
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Electrical Equipment ◽  
Electrical Safety ◽  
Safety Level ◽  
Electrical Systems ◽  
Safety Research ◽  
Relevant Task ◽  
Short Circuits ◽  
Method Of Assessment

Introduction. Overvoltage caused by single-phase ground short circuits are the main reason of multiple breakdowns of insulation. Assessment and forecast of overvoltage in SPGSC in the 6–10 kV mains is therefore a relevant task, and the solution to this problem will make it possible to select effective methods and means of limiting overvoltage and improve the conditions of electrical safety. Research aim is to improve the methods of assessing and forecasting overvoltage of arch SPGSC in the 6–10 kV mains of mining facilities. Methodology. This article provides analysis of current hypothesis and methods for the assessment of overvoltages in the single-phase ground short circuit (SPGSC) mode. Currently the hypothesis of Peterson, Peters–Slepyan, Belyakov–Djuvarl does not fully reflect the factors that affect the maximum overvoltage emergence of the single-phase arc ground short circuits in the 6–10 kV mains, because they don’t take into account the capacitive current value of SPGSC, arc combustion conditions, lifetime of SPGSC, inductance of engines and transformers. Results. There have been obtained dependences that show the dependences of frequency with which overvoltage happens from the factors that were mentioned above. The shown dependences can be used for calculation and assessment of overvoltage in the 6–10 kV mains with different neutral modes to justify the need for activities that will protect electrical systems, transformers, electrical engines from overvoltage in the SPGSC mode and considering its lifecycle. Summary. It was established that from the electrical safety positions of 6–10 kV mains with resistive or combined modes of neutrals on mining and extractive facilities create conditions for the safer exploitation of technological complexes, facilities and electrical equipment, because it can reduce maximum overvoltage ratios by half and thus reduce the number of repeated breakdown of insulation in the SPGSC mode.

scholarly journals Single-phase ground short circuits in the 6–10 kV mains and electrical traumas in the coal mines

2020 ◽  
pp. 113-123
Author(s):  
Kuzmin Sergei ◽  
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Coal Mines ◽  
Electrical Energy ◽  
Electrical Equipment ◽  
Electrical Safety ◽  
Electrical Systems ◽  
Switching Overvoltage ◽  
Short Circuits ◽  
Quality Of Electrical Energy

Introduction. This article provides analysis of electrical traumas and single-phase ground short circuits (SPGSC) in the 6–10 kV electrical systems in the period from 1995 to 2018. It has been shown that reduction in the number of SPGSC will improve electrical safety at coal mines. Research aim is to determine the interrelation between the indicated factors based on the statistical data in the 6–10 kV mains of coal mines according to SPGSC minor and moderate electrical traumas. Methodology. Coal production, development of single-phase ground short circuit and changes in numbers of injuries in the period from 1995 to 2018 have been analyzed making it possible to vividly and qualitatively estimate the dynamics of changes in coal output, the number of SPGSC, electrical traumas and determine the interrelation between these parameters. The discovered interrelation between SPGSC and electrical traumas allows to handle the problem of improving the electrical safety more seriously by means of reducing the number of SPGSC. Results. This article shows the main reasons of single-phase ground short circuit incidence depending on time. The article shows the main ways to lower the amount of single-phase ground short circuit in the 6–10 kV electrical systems of coal mines. Summary. Significant reduction in the number of single-phase ground short circuit in the 6–10 kV electrical systems and, as a consequence, reduction of electrical traumas at coal mines can be achieved by means of effectively limiting switching overvoltage, overvoltage in the mode of single-phase ground short circuit, reaching high selectivity of protection from ground short circuit and improving the quality of electrical energy, and limiting the overloading of electrical equipment and cables.

scholarly journals Research on Safety Technology for High-Speed Interruption for Mining Flameproof Movable Substation

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 934
Author(s):  
Yanwen Wang ◽  
Le Wang ◽  
Sven G. Bilén ◽  
Yan Gao
Keyword(s):  
Solid State ◽  
High Speed ◽  
Single Phase ◽  
Low Voltage ◽  
Short Circuit ◽  
Rate Of Change ◽  
Simulation Experiments ◽  
Gas Detonation ◽  
Ultra High Speed ◽  
Short Circuit Fault

Due to the working condition of low-voltage cabling from the mining flameproof movable substation to the loads of the mining face being poor, it is easy to cause various external mechanical damages to the cable sheaths. Furthermore, a single-phase earth leakage fault or short-circuit fault can occur when the low-voltage cable sheaths are damaged, and electric sparks caused by these faults can lead to a gas explosion. As the gas detonation time caused by the above faults is usually more than 5 ms, the high-speed interruption solid-state switch which controls the cables must cut off the current within 3 ms. This requires the action time of the solid-state switch to be less than 1 ms, and at the same time, the sampling and calculation time of the relay protection must be less than 2 ms. Based on these problems, this paper proposes the use of a high-speed solid-state circuit breaker (SSCB) topology at the neutral point of transformer, and analyzes the conduction mechanism and shut-off mechanism of the current of the SSCB. It presents an ultra-high-speed algorithm based on pattern recognition of single-phase earth leakage fault protection, and an ultra-high-speed algorithm of short-circuit fault which is based on the rate-of-change of the current. Finally, through computer simulation experiments and semi-physical simulation experiments, the feasibility of the above three technologies is verified to ensure that when a single-phase earth leakage fault or short-circuit fault occurs in the low-voltage cable, the solid-state switch which is installed in the mining flameproof movable substation will cut off the current within 3 ms.

Short-Circuit Model and Simulation Characteristics of Synchronous Generators

2012 ◽  
Vol 241-244 ◽  
pp. 709-716
Author(s):  
Wan Qing Song ◽  
Qi Zhong Liu ◽  
Xu Dong Teng ◽  
Chao Gang Yu
Keyword(s):  
Theoretical Analysis ◽  
Simulation Model ◽  
Short Circuit ◽  
Influence Factors ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Model And Simulation ◽  
Simulation Results ◽  
Physical Quantities ◽  
Tremendous Impact

In this paper, the electrical transient mode of synchronous generators is studied, four different simulation model of synchronous generator on sudden short circuit was built, various physical quantities were studied by simulation during the short circuit. By comparing theoretics with simulation, various physical quantities of synchronous generator produced tremendous impact and surge during the sudden circuit and they stabilized in the proceeding state of short circuit. Thoroughly simulation analyzed, the results of simulation are identical with theoretical analysis. The simulation results show that these influence factors should be considered when we design the relay protections.

scholarly journals Adaptive Armature Resistance Control of Virtual Synchronous Generators to Improve Power System Transient Stability

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2365
Author(s):  
Daniel Carletti ◽  
Arthur Eduardo Alves Amorim ◽  
Thiago Silva Amorim ◽  
Domingos Sávio Lyrio Simonetti ◽  
Jussara Farias Fardin ◽  
...  
Keyword(s):  
Adaptive Control ◽  
Power System ◽  
Transient Stability ◽  
Short Circuit ◽  
Stability Margin ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Resistance Change ◽  
Clearing Time ◽  
Fault Current Limiters

The growing number of renewable energy plants connected to the power system through static converters have been pushing the development of new strategies to ensure transient stability of these systems. The virtual synchronous generator (VSG) emerged as a way to contribute to the system stabilization by emulating the behavior of traditional synchronous machines in the power converters operation. This paper proposes a modification in the VSG implementation to improve its contribution to the power system transient stability. The proposal is based on the virtualization of the resistive superconducting fault current limiters’ (SFCL) behavior through an adaptive control that performs the VSG armature resistance change in short-circuit situations. A theoretical analysis of the problem is done based on the equal-area criterion, simulation results are obtained using PSCAD, and experimental results are obtained in a Hardware-In-the-Loop (HIL) test bench to corroborate the proposal. Results show an increase in the system transient stability margin, with an increase in the fault critical clearing time (CCT) for all virtual resistance values added by the adaptive control to the VSG operation during the short-circuit.

scholarly journals Bidirectional Short-Circuit Current Blocker for DC Microgrid Based on Solid-State Circuit Breaker

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 306 ◽  
Author(s):  
Lujun Wang ◽  
Boyu Feng ◽  
Yu Wang ◽  
Tiezhou Wu ◽  
Huipin Lin
Keyword(s):  
Solid State ◽  
Low Voltage ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Short Circuit Current ◽  
Rotational Inertia ◽  
Dc Microgrid ◽  
Protection Strategy ◽  
Solid State Circuit ◽  
Solid State Circuit Breaker

In order to solve the imminent problem in that the traditional protection strategy cannot meet time requirements, together with the fact that the rotational inertia of a DC microgrid is small and short-circuit fault develops rapidly, a bidirectional short-circuit current blocker (BSCCB) based on solid-state circuit breaker for a DC microgrid is proposed. Firstly, the bidirectional current blocking circuit structure is proposed based on the analysis of key components. Then, a top-level differential protection strategy is developed based on the aforementioned proposal. Finally, the performance of the blocking circuit is simulated and verified by experiments. The results show that the proposed method can block short-circuit current within 4 ms, and the response speed of the protection strategy is very fast compared with previous approaches. BSCCB also has reclosing, bidirectional blocking and energy releasing functions. The current blocker proposed in this paper can be reused multiple times and has a promising future in low-voltage DC microgrid application.

scholarly journals Comparative Simulation Study on Synchronous Generators Sudden Short Circuits

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Lucian Lupşa-Tătaru
Keyword(s):  
Mathematical Model ◽  
Time Domain ◽  
Short Circuit ◽  
Structural Equations ◽  
Process Models ◽  
State Variables ◽  
Synchronous Generators ◽  
State Equations ◽  
Starting Point ◽  
Short Circuits

Although of a great extent in time, the research works directed at studying transients in synchronous generators have not yet provided fully sufficient comparative studies in respect to sudden short circuits of the machine. The present paper puts forward novel and comprehensive process models for dynamic simulation of short circuit faults of initially unloaded synchronous generators, using the generalizedd-q-0 mathematical model as starting point in derivation. Distinct from the time-domain analysis, the technique proposed here allows an effective comparative overview by employing a specialized procedure to perform repeated time-domain simulations accompanied by peak values recording for the various circumstances. The time consuming matrix numerical inversion at each step of integration, usually performed when selecting currents as state variables, is eliminated by advancing the process models in a convenient split matrix form that allows the symbolic processing. Also, the computational efficiency is being increased by introducing a set of auxiliary variables common to different state equations. The models derivation is carried out without altering the structural equations of the generalizedd-q-0 mathematical model of synchronous generators whilst the simulation results are both compared and discussed in detail.

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