Analysis Of Overvoltages Research Articles

Simulation analysis of overvoltage caused by grounded short circuit in the collection system of far-offshore wind farms

Abstract As the distance from the shore of offshore wind farms increases, MMC-HVDC technology is gradually gaining attention in its grid connection schemes. A broadband electromagnetic transient model of offshore wind farms with a total capacity of 800 MW connected to the grid via a flexible direct current transmission system is developed. After three types of grounded short circuit faults occur at different fault positions within the power collection system, the characteristics of overvoltage are obtained and they are analyzed on the basis of considering the low voltage ride-through capability of the direct-drive permanent magnet wind power generator. Combining the two factors of range and amplitude, the results show that the overvoltage phenomenon is the most serious when a two-phase grounded short circuit occurs at the converging busbar, which can be the focus of the study when setting up overvoltage protection.

Experimental electromagnetic compatibility of conducted electromagnetic interferences from an IGBT and a MOSFET in the power supply

Introduction. Most electromagnetic compatibility studies carried out in the context of power switch research are generally valid for low frequencies. This frequency restriction appears to be too restrictive for a complete analysis of the electromagnetic interference conducted. The novelty of this work lies in the load-dependent an optimal selection of IGBTs and MOSFETs for least-disturbance power switching in the frequency range from 150 kHz to 30 MHz, based on an optimal experimental selection procedure and show the impact of load value on switch switching and noise generation. Purpose. Analysis of the fundamental possibility of selecting a switching device with a power supply based on an experimental measurement which allows to increase the reliability of the entire mechanism operation and significantly simplify the design. Methods. In this paper, the proposed study is used and compared with experimental results at low and high frequencies. Then, a comparison is made for conducted electromagnetic interference (common-mode and differential-mode) generated by IGBT and MOSFET for different loads, and the proposed methodology is verified on an experiment suitable for predicting terminal overvoltage analysis and conducted electromagnetic interference problems. Practical value. The primary method for establishing a conducted electromagnetic interference source for switching devices is based on IGBT and a MOSFET depending on the resistive load. References 22, figures 17.

Analysis and suppression of operational overvoltage and inrush current for high‐speed trains by automatic phase‐switching technique

AbstractWhen a high‐speed train approaches the insulated phase‐splitting section embedded between neighbouring power supply arms, the vacuum circuit breaker (VCB) installed on trains must be disconnected to maintain the traction power supply system as a no‐load condition for completing phase‐switching action, as the train passes through the phase‐splitting section depending on its inertia. However, when operating VCBs, the arc is easily triggered between the mobile contacts inside, accompanied by an overvoltage impulse. Herein, to explore the generating mechanism of inrush current and operational overvoltage, a model describing the ‘substation‐catenary‐train’ traction power supply system is launched based on an equivalent circuit modelling technique. Through the analysis of the transient VCB operational process, the phase of catenary voltage is directly related to the characteristics of the VCB switching‐on overvoltage, as the traction current's phase angle is relevant to the amplitude‐frequency characteristics of the VCB switching‐off overvoltage. Inrush current as a noteworthy element is related to the traction transformer's remanence. The automatic phase‐switching technique is utilised to suppress both operational overvoltage and inrush current, as the optimal combination of VCB switching‐on and switching‐off phases considering the balance between overvoltage and inrush current is achieved based on the particle swarm algorithm.

The Impact Analysis of Operational Overvoltage on Traction Transformers for High-Speed Trains Based on the Improved Capacitor Network Methodology

The Impact Analysis of Operational Overvoltage on Traction Transformers for High-Speed Trains Based on the Improved Capacitor Network Methodology

High frequency Modelling of Cables in PWM Motor Drives by Using Polynomial Functions based Parameters

- The high frequency behaviour of the cables in pulse width modulation (PWM) motor drives is of a crucial importance in the analysis of transient overvoltages and conducted electromagnetic interference (EMI) propagation, both common and differential mode. In order to give a tool for simulation of the above cited phenomena, a new method for high frequency cable modelling is proposed in this paper. The method is based on the measurement of the impedance frequency responses of the cables in short and open circuit conditions. The lumped parameters cable behaviour is described by polynomial functions in frequency domain. For a given frequency a simple equivalent circuit representation of the cable is obtained. The proposed model is easily implemented in Matlab/Simulink and it is validated comparing the computed frequency impedance responses of the cable, loaded by either a resistive load or an induction motor, to the corresponding measured ones. Moreover, the prediction, by the model, of the overvoltage at the motor terminals in a long-cable PWM drive is performed. The proposed model are also compared with some commonly used high frequency cable models presented in technical literature.

Analysis and Mitigation of Transient Overvoltage and Voltage Imbalance in Submodule Capacitors for MMC-Based Grid Emulators

Analysis and Mitigation of Transient Overvoltage and Voltage Imbalance in Submodule Capacitors for MMC-Based Grid Emulators

Analysis and mitigation techniques of overvoltages due to insulator transient arcs clearing on a 500 kV OHTL

In high-voltage OHTL, Overvoltages and arc currents due to insulator transient arcs clearing severely affect the stability of power systems.In this paper, a 500 kV Egyptian OHTL was simulated using ATP-EMTP software package. The insulators transient arcs clearing of the system were tested under different impedances of tower footing, locations of insulator arc tower, angles at which the arc initiate. Additionally, the effects of the corona phenomenon were taken into account to achieve realistic study. Furthermore, these factors thoroughly were analyzed to determine worst-case scenarios. Also the paper evaluated the performance of the overvoltage mitigation methods based on the installation of neutral shunt reactors, MOSA (Metal Oxide Surge Arresters), or combinations of both.The results demonstrated that the combination of MOSA and neutral shunt reactors was the most effective mitigation technique, reducing overvoltages by approximately 57.4 %, arc currents by 80 %, and arc extinction time by 27.3 %Notably, the most severe overvoltages and peak arc currents occurred at an angle of θ = 180° and footing impedance 30Ω. Additionally, the corona phenomenon played a role in reducing the severity of overvoltages, arc currents, and arc extinction time by approximately 56 %, 56 %, and 1.8 %, respectively. Finally, These findings provide valuable recommendations for mitigating overvoltages, arc currents, and arc extinction time during insulator arc clearing events.

Analysis of switching overvoltages and protection from atmospheric overvoltages for 400kV switchgears in the Kosovo Power System using ATP/EMTP

Analysis of switching overvoltages and protection from atmospheric overvoltages for 400kV switchgears in the Kosovo Power System using ATP/EMTP

Analysis of overvoltages across line insulator strings considering the ground-wire and phase conductors corona

This paper assesses the influence of corona effect on the overvoltages developed across the insulator strings of overhead transmission lines due to lightning. The influence of corona is investigated considering lightning strikes to the tower top and shielding wires at midspan. A large range of soil resistivity and lightning currents peaks are evaluated in the analysis, and the stress across the insulator strings is evaluated applying the integration method. Simulations are carried out in the Alternative Transient Program (ATP/EMTP), wherein the corona effect is represented through the accurate Suliciu corona model, which was implemented using the MODELS interface and combined with J. Marti line model. Furthermore, it was also represented the wideband behavior of tower grounding system. Results showed that corona effect has a minor influence in the overvoltages across the insulator string for strikes to the tower top. However, it strongly influences the overvoltages across line insulators ensuing from a lightning strike to the shielding wire at the midspan, leading to a decrease in the peak value of the lightning current that causes line flashover.

Analysis of temporary overvoltage due to inverter-based distributed generation in networked distribution systems

This paper analyzed the temporary overvoltage (TOV) problem in the network distribution system. The TOV shows different patterns depending on the type of distributed energy resources (DERs) and the grounding method. In particular, the inverter-based distributed generations (IBDGs) also show different patterns as inverter’s dynamic characteristics depending on the classification of grid forming (GFM) and grid following (GFL). The paper reviewed existing factors affecting TOV according to the inverter type. In addition, the TOV was simulated in various topologies of distribution systems, indicating that distribution system topology can solve the TOV problem regardless of the inverter type. This paper compared the TOV in the radial distribution system and the networked distribution system (NDS), and as a result, the operation through NDS can be a solution to the TOV problem. In addition, TOV in the NDS is analyzed through simulation, considering various elements of the distribution system to prove a more robust solution.

On-line Monitoring of Instantaneous Over-voltage Intelligent Monitoring of EMUs

Since high-speed EMUs have high requirements for the reliability of the traction power supply system and the safety of train operation, the online monitoring and analysis of transient over-voltage are of great significance. By analyzing and comparing the characteristics of the existing power grid over-voltage online monitoring devices at home and abroad, and due to the difficulty in detecting the power grid voltage on the high-speed train, a new type of over-voltage online monitoring using the broadband transmission characteristics of the equipment is proposed for the high-speed train. The principle of the scheme is to reconstruct the real-time voltage waveform of the primary side of the transformer by convolving the secondary side voltage waveform of the vehicle-mounted voltage transformer through the fast Fourier transform with the transformer-specific transmission parameter model and to correlate the relevant data, such as power, voltage fluctuation, harmonic distortion, etc. Simultaneously, simulation and experiments are carried out to verify the validity and stability of the scheme algorithm. The experimental results show that the system has good response characteristics, high measurement accuracy, and stable and reliable working conditions. The system achieves the expected design goals, and it has been successfully applied to the online monitoring equipment of EMU power quality. While monitoring the over-voltage of the power grid, this system provides data support for the research on the aging and life of the onboard high-voltage electrical equipment.

Analysis of transient overvoltages and Self Protection Overvoltage of PV inverters through RT-CHIL

In power systems, Single-Line-to-Ground (SLG) faults are the most common type of fault. When a three-phase four-wire system supplied by an ungrounded synchronous generator is subjected to SLG faults, the unfaulted phases are expected to exhibit significant ground-fault over-voltage (GFOV). Mitigation of this is via effective grounding, as described in IEEE Std 62.92.2. However, for inverter-based resources (IBRs), the physical mechanism that leads to GFOV in synchronous machines is not present. This paper investigates whether GFOV is a problem in IBRs, and whether conventional mitigation requirements, such as providing a grounding transformer (GTF), are suitable for IBR installations. To answer these questions, a Controller Hardware-in-the-Loop (CHIL) based performance analysis is conducted. To this end, different simulation models have been developed to analyze the IBRs control and protection response. The models are comprised of a 13.2 kV, 500 kW distribution system fed by a grid connected PV inverter which was simulated in Typhoon HIL 604 real time simulator, with a IEEE Std 1547-2018 compliant external physical controller connected in the loop. The experimental set-up and tests conducted are explained and results are analyzed, showing that effective grounding requirements are much different than those for traditional generators.

Modeling and Experimental Analysis of Overvoltage and Inrush Current Characteristics of the Electric Rail Traction Power Supply System

High-speed EMUs (electric multiple-units) frequently pass through the phase-separation zone during operation. Overvoltage generated during the operation of the vehicle-mounted circuit breaker has a long duration and high waveform steepness, which accelerates the service life of the vehicle-mounted equipment and is likely to cause insulation failures. For the above-mentioned problems, the operating overvoltage characteristics of high-speed EMU were obtained by traction substation-catenary-EMUs system (SCES) analysis and experiments, thus deriving the influences of the closed phase angle and the residual magnetism of the vehicle-mounted transformer on operating overvoltage. The results showed that the voltage phase of the catenary significantly affected the operating overvoltage, and the closed switching overvoltage was small at 0–40°, 140–210° and 320–350°. The voltage on the primary side of the vehicle-mounted transformer was 60.78 kV, with the transient impact of high-frequency oscillation overvoltage of 22.71 kV, and an initial period of oscillation of 0.01 ms. Then, the period became longer, and it took 0.5 ms for the high-frequency oscillation from attenuation to disappearance. Finally, a scheme of series reactance suppression devices was proposed to protect vehicle-mounted voltage transformers. This work is to provide data support for the insulation design and system protection of a traction power supply system.

Research on Lightning Overvoltage Characteristics of High-Voltage Diode Rectifier

Failure of the high-voltage diode rectifier caused by lightning will cause huge losses. The traditional analysis of overvoltage induced by the high-voltage diode rectifier shell under lightning stroke cannot adapt to the overvoltage process caused by lightning stroke-induced conduction invading the inside of the high-voltage diode rectifier. Therefore, this paper proposes to establish a high-frequency equivalent model of the core components of the high-voltage diode rectifier, including diodes, reactors, transformers, and overhead lines. On this basis, a lightning overvoltage model of lightning-induced conduction into the high-voltage diode rectifier is built, and the transient process of diode lightning overvoltage under the constraint of reverse recovery charge is analyzed. Then, we describe the transient distribution of overvoltage in high-voltage diode rectifiers caused by lightning stroke. The transient distribution of overvoltage induced by lightning in series diodes under different diode equivalent models is analyzed by simulation. The simulation results show that the inconsistent parameters of series diodes can easily lead to diode damage due to uneven voltage distribution when lightning strikes. Therefore, this paper puts forward a scheme to reduce lightning damage, including selecting diodes with the same parameters and adding fast-melting fuses at the transformer’s secondary side and in front of the series diode bridge arm. The simulation shows that the scheme proposed in this paper can effectively prevent the high-voltage diode rectifier from being damaged by lightning strikes.

A high-frequency modeling of AC motor in a frequency range from 40 Hz to 110 MHz

Introduction. Most electromagnetic compatibility models developed for the study of three-phase induction machines are generally valid for low and medium frequencies (<< 1 MHz). This frequency limit seems to be too restrictive for the overall study of conducted electromagnetic interference. In this paper, the model is using the proposed model and compared with experimental results in low and medium frequency. And then, the high-frequency modeling of induction motor is presented new method based on transfer function model. The proposed methodology is verified on an experimental and simulation, it’s suitable for prediction of the terminal overvoltage analysis and electromagnetic interference problems and common-mode and differential-mode currents. The novelty of the work consists to develop an improved high-frequency motor model based on transfer function to represent the motor high-frequency behavior for frequency-domain analyses in the frequency range from 40 Hz up to 110 MHz .The purpose of this work is to study the common-mode impedance and the differential-mode impedance of AC motor. The determination of these impedances is done for firstly both common and differential modes at low and medium frequency, and then common-mode and differential-mode characteristics at high frequency. Methods. For the study of the path of common-mode and differential-mode currents in typical AC motor (0.25 kW, 50 Hz) an identification method in high frequency for induction motor has been proposed based on the transfer function in differential-mode and common-mode configuration. The low and medium frequency model were presented in the first time based on equivalent circuit of electrical motor. Then, the common-mode and differential-mode impedances were defined in high frequency using asymptotic approach. This motor was studied by MATLAB Software for simulation and also experimental measurements. Results. All the simulations were performed using the mathematical model and the results obtained are validated by experimental measurements performed in the University of the Federal Armed Forces Hamburg in Germany. The obtained results of common-mode and differential-mode at low frequency, medium and high frequency are compared between simulation and experiment.

Plane-Wave Coupling Analysis of a Distribution Line With a Multipoint Grounded Shield Wire and Surge Arresters Using the Three-Dimensional FDTD Method

A high-frequency electromagnetic plane wave arises owing to a high-altitude electromagnetic pulse (HEMP), which may cause overvoltages in distribution lines and insulation failure. To protect distribution lines from such overvoltages properly, it is necessary to evaluate the effectiveness of countermeasures. Nowadays, the finite-difference time-domain (FDTD) method, which is one of the full-wave numerical approaches, has become a powerful tool for analyzing electromagnetic transient phenomena. In this article, first, we propose a simplified approach to modeling an impinging plane wave by taking into account homogeneous soil parameters in the three-dimensional FDTD method on the basis of a total field/scattered field technique for the analysis of HEMP-based plane-wave coupling. Second, using the proposed technique, we carry out the statistical analysis of overvoltages in a three-phase distribution line and evaluate the effectiveness of a multipoint grounded overhead shield wire and surge arresters, which are commonly used as lightning protection measures, while modeling the reinforcing bars of concrete utility poles, earth electrodes, and vertical grounding wires to simulate a realistic condition.

A Study of Lightning Performance to Multi-grounded System of KEPCO MV and LV Distribution Network

This paper presents the indirect lightning performance evaluation of Korea Electric Power Company (KEPCO) medium voltage (MV) and low voltage (LV) lines. The main topic of this paper is to analyze an effect of the grounding systems on the indirect lightning performance of MV and LV distribution lines. To this end, we define the models of the MV and LV distribution systems for the analysis of distribution line surge overvoltage due to lightning. With reference to the data typically adopted by KEPCO, the research describes and motivates the use of the most suitable models of distribution lines, transformers, and surge arresters (SAs) to be implemented in EMTP like simulation environments. The sensitivity of the lightning performance of the distribution lines to different configuration of MV and LV grounding systems, distance between SAs, as well as presence of overhead ground wires is also analyzed. Regarding overvoltage, both the temporary overvoltage and the surge overvoltage are considered. The presence of SAs at the MV terminals of distribution transformers is also considered.

Characteristic analysis of the VCB operational overvoltage for high-speed trains considering arc reignition phenomenon

ABSTRACT Due to the constant pursuit for higher operating velocity, the traction power capacity for high-speed trains needs to be enlarged. When the train passes approach the insulating sections set between the two neighbouring contact lines carrying the traction current with different phases, the vehicle-mounted vacuumed circuit breaker (VCB) needs to be switched off. Generally, the arc may generate when connecting or separating the contacts, when switching on or off the VCB. In order to investigate the characteristics of the reignition overvoltage the ‘train-rail-catenary’ traction power supply model considering the reignition process between the VCB’s contacts is launched in this paper. The impact of the dielectric strength recovery rate between the contacts of the VCB on the number of reignition and the amplitude of the reignition overvoltage is analysed based on the experimental and simulation results. Ultimately, the corresponding restraining measures are proposed for suppressing the reignition overvoltage.

A Method to Determine Fast Charging Procedures by Operando Overvoltage Analysis

A method to determine threshold voltage conditions for Li plating in lithium ion battery cells is presented. Transferring open-circuit values determined in a 3-electrode electrochemical measurement onto a 2-electrode cell setup, the boundary conditions for Li plating can be assessed. In multi-layer pouch cells, these boundary conditions agree perfectly with the exact onset of Li plating as proven by post mortem analysis. By knowledge of the Li plating threshold voltage conditions, plating-free fast-charging procedures can be exercised leading to an increase in charging rate by 84% and 79% for two different cell systems, respectively. Cycling above or below the Li plating threshold voltage, Li plating occurrence can be deliberately controlled. Comparing plating and plating-free conditions, the applied charging voltage properties differ hardly. Hence, the applied analysis of overvoltage proves a more sensitive and specific operando method to predict Li plating.

Transient overvoltage analysis in the medium voltage substations based on full-wave modeling of two-layer grounding system

In this paper, a comprehensive investigation of substation grounding soil structure effects on switching/lightning transients is presented. The full-wave computational solution Method of Moments (MoM) is adopted to solve Maxwell’s equations. The significant advantage of this technique is its ability to deal effectively with substation grounding systems (SGSs) at high frequency. This evaluation is carried out considering two soil structures: (1) a uniform soil and (2) soil with a layered structure. The impacts of both soil structures on the peak transient overvoltage values are compared. To begin with, the harmonic impedance matrix (HIM) of the layered multi-terminal SGS is computed. Then, a vector fitting approach is employed to incorporate the accurate SGS behavior by relying on the obtained HIM into time domain simulations. Finally, the transient overvoltages and maximum ground potential rise (GPR) are computed. The chief contribution of this paper is the transient assessment of the two-layer multi-terminal soil structure of the large SGS taking into account the frequency dependence model of the electrical parameters of soil, which is not generally investigated and instead, treated simplistically. According to the results of the study, the lack of an exact grounding system models may lead to underestimations/overestimations of the GPR and the overvoltage values. The results demonstrate the need for the grounding modeling of SGS considering layered soil structure to be incorporated into power system transient analysis in a wide range of frequencies.