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Capacitor switching is one of the most important sources of generating transient overvoltage and inrush current of electrical power system. Energizing transient may reduce the life span of capacitor banks, damage of power system equipment and insulation failure. This paper, presents three technologies used to mitigate transients caused by capacitor switching. ATP program is used to simulate capacitor...
Voltage sags and switching transients are the most common power quality disturbances which affect many customers in the distribution system. Detection methods are required to quantify these aspects of the quality of the power supply. Voltage sags and switching transient which occur at higher voltages will normally spread through a utility system and will be transmitted to lower voltage systems. In...
High Impedance Fault (HIF) has long been a challenging problem in network protection. This is because of its difficulty to be detected and discriminated accurately and reliably. In real cases, arcing is usually associated with HIFs. In this paper, arcing currents are produced by setting up a HV experiment. Normal switching transients are also produced by simulation or experiment. They are then analysed...
This paper presents a new method for relative location of voltage sags and capacitor switching transients based on voltage measurements only. Voltage sags caused by network faults and transients caused by bank capacitor energizing are considered in this work. The algorithm automatically operates for assessing power quality, characterising and extracting information from voltage records obtained from...
Capacitor switching transients is an important power quality concern. The power quality impact of a capacitor switching event is traditionally evaluated with the Electromagnetic transients (EMT) simulation program. This requires the creation of EMT cases for studying the event, which can be a very time consuming process. All utility companies conduct load flow and short-circuit studies for their systems...
In this paper, two technologies are used to mitigate transients caused by capacitor switching in distribution feeders. The basic concept of capacitor bank switching transients and its mitigating techniques is presented here. The MATLAB /SIMULINK software is used to simulate the energization of a controlled capacitor bank in a specific substation feeder, with and without employing mitigation devices...
Although capacitors provide voltage support and correct displacement power factor on power distribution lines, capacitor switching transients are the second most common power quality events, after voltage sags. Capacitor switching transients can disrupt loads that are sensitive to overvoltage sub-cycle transients, including adjustable speed drives, data communication systems and process controls....
This paper presents an effective technique for tracking and finding the direction of switched capacitor banks in distribution system that generate switching transient when certain number of power quality meters exist. This technique uses modal current and voltage signals that can be constructed by combining three-phase current and three-phase voltage. This method consists of two indices. First index...
This work is concentrated on transfer of power quality disturbances in active distribution network containing small hydro power plants (SHP). Investigations are based on the dispersed synchronized measurements using power quality recorder installed in the two substations connected to the same medium voltage line. Dynamic aspect of SHP work represented by switching on capacitor banks are tracked in...
This paper presents an integration of S-Transform and Probabilistic Neural Network (PNN) technique for identifying the location of a switched capacitor causing a power quality problem. The transient caused by the capacitor switching is one of the important power quality (PQ) problems since it may adversely affect the system as well as sensitive loads. S-Transform has the ability to detect the disturbance...
This paper proposes an identification scheme of capacitor switching transients using Approximate Entropy (ApEn) approach. Detailed procedures of the proposed scheme are presented. Simulation and real results indicated that the scheme is feasible for classification of power event signals.
Islanding phenomenon is a problem for Distributed Generator (DG) based networks leading to troubles in voltage and frequency control and other power quality issues. This paper describes the development of a method based on Discrete Wavelet Transform (DWT), in order to detect islanding for DGs. This method detects the islanding state only by evaluating the terminal current of DGs. Hence, different...
Modern numerical relays have substantially reduced false operation of overcurrent relays used for capacitor protection. However, faster and more reliable operation can be useful. This paper proposes a morphological filter for fast and clear distinction between fault currents and switching currents that can benefit all types of overcurrent relays used for protection of capacitor banks. The filter performance...
In this paper, internal fault protective relay maloperation of assembling capacitor bank caused by switching-on transient harmonics is analyzed. Mathematical expressions describing the adaptive settings of single-wye, dual-wye and bridge connections are given. The realistic action of internal fault protections under high amplitude harmonic conditions is possibly very different from theoretic setting...
In this paper, a method is proposed for determining the exact location of switched capacitor banks in distribution systems. The method consists of two steps. In the first step, the technique is based on measurement of voltage and current transients created by capacitor switching. The hypothesis states that: The slope of voltage and current transient wave forms created by capacitor switching immediately...
There are two major switch-on transient phenomena of the capacitor: one is the transient over-voltage and the other is the inrush current. The transients will shorten the lifetime of the capacitor and furthermore they will damage the contactors of the switching device. In this paper, a novel method for mitigating the capacitor switch-on transients is developed. The operation principle of the proposed...
Capacitor bank switching classification using scale selection continuous wavelet transform is an approach to develop power quality diagnostic feature to analyze the origin and possible cause of transient disturbance in the industry facility. The scale selection wavelet transform selectively perform continuous wavelet transform from scale 1 to scale 70 at the dilation interval of one per scale whereby...
In this paper, a new method is proposed for tracking and finding the location of shunt switched capacitor banks in distribution systems. The technique is based on measurement of voltage and current transients created by capacitor switching. The hypothesis states that: ??the slope of voltage and current transient waveforms created by capacitor switching immediately before and after the switching instant...
In this paper a novel algorithm is proposed in order to determine the exact location of switched capacitor banks in distribution systems. The method consists of two steps. In the first step, the direction of switched capacitor bank is determined by evaluating power factor changes before and after the switching instant. In the second step, a method based on linear circuit theory is used to estimate...
This paper develops a signal processing, time-frequency analysis-based analytic solution to locate transient capacitor switching disturbances. The flow of transient disturbance energy caused by the capacitor switching is determined by the time and frequency localized phase difference. Cross time-frequency analysis provides time- and frequency-localized phase difference between the transient voltage...
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