High frequency impedance based fault location in distribution system with DGs

Distributed generations (DGs) in the distribution systems are connected into the buses using power electronic converters. During fault, it is challenging to provide a constant impedance model for DGs in the system frequency due to the variable converter control strategies. System frequency impedance measurement based fault locations can be influenced by the converters’ fault behaviour. This study addresses this problem by proposing a wide-area high-frequency impedance comparison based fault location technique. The high-frequency impedance model of DG is provided. Based on the constant DG impedance model in high-frequency range, the faulted line sections can be distinguished by comparing the measured impedance differences without requiring the exact distribution system parameters. Simulation results show that the proposed wide-area transient measurements based fault location method can provide accurate faulted sections in the distribution systems with DGs regardless of the load and DG output variations, measurement noise, unbalanced loads and islanding operations

High frequency impedance based fault location in distribution system with DGs

Distributed Generations (DGs) with power electronic devices and their control loops will cause distortion to the fault currents and result in errors for power frequency measurement based fault locations. This might jeopardize the distribution system fault restoration and reduce the grid resilience. The proposed method uses high frequency (up to 3kHz) fault information and short window measurement to avoid the influence of DG control loops. Applying the DG high frequency impedance model, faults can be accurately located by measuring the system high frequency line reactance. Assisted with the DG side recorded unsynchronized data, this method can be employed to distribution systems with multiple branches and laterals

Influence of an inverter based DG on a double-ended fault location scheme

This paper describes the influence of Distributed Generation (DG) on a double ended fault location based on measuring the high frequency fault transients. The additional non-fundamental frequency current components from DG will influence the accuracy of an impedance based fault location technique based on non-fundamental frequencies. A double-ended impedance based fault location technique that utilizes the high frequency content (up to 5 kHz) is studied. The study showed that double-ended method is still able to locate a fault with a maximum error of 4% compared to the case without DG which showed a percentage error up to 2%

Fast fault location scheme for distribution systems based on fault transients

This paper presents a combined double-end and single-end fault locator for distribution systems. The technique lies under the impedance based category and uses the fault generated high frequency components to locate the faults. The combination of double-end and single-end allows the method to discriminate between faults on the main feeder and those on laterals. Also, the method only requires a short data window as it depends on the high frequency components. The evaluation of the method considers different system and fault parameters e.g. loading taps, loading unbalance, fault type and fault resistance. To validate the proposed technique, the IEEE 34 nodes system is used to simulate different test cases

Fast fault location scheme for distribution systems based on fault transients

This paper presents a combined double-end and single-end fault locator for distribution systems. The technique lies under the impedance based category and uses the fault generated high frequency components to locate the faults. The combination of double-end and single-end allows the method to discriminate between faults on the main feeder and those on laterals. Also, the method only requires a short data window as it depends on the high frequency components. The evaluation of the method considers different system and fault parameters e.g. loading taps, loading unbalance, fault type and fault resistance. To validate the proposed technique, the IEEE 34 nodes system is used to simulate different test cases

Influence of an inverter based DG on a double-ended fault location scheme

This paper describes the influence of Distributed Generation (DG) on a double ended fault location based on measuring the high frequency fault transients. The additional non-fundamental frequency current components from DG will influence the accuracy of an impedance based fault location technique based on non-fundamental frequencies. A double-ended impedance based fault location technique that utilizes the high frequency content (up to 5 kHz) is studied. The study showed that double-ended method is still able to locate a fault with a maximum error of 4% compared to the case without DG which showed a percentage error up to 2%

Sparse Voltage Measurement-Based Fault Location Using Intelligent Electronic Devices

This paper proposes a fault-section location method based on sparse measurements, aimed at asymmetrical faults. A virtual current vector is defined to indicate the faulted section, which is sufficiently sparse except that the fault position corresponding entries are nonzero. To simplify the algorithm, the virtual vector is fixed by amplitudes of voltages and impedances and the feasibility is demonstrated. The Bayesian Compressive Sensing theory is introduced to reduce the number of required intelligent electronic devices (IEDs). In addition, the minimal number of IEDs and their allocation are discussed. The performance of the proposed method is validated in a 69-bus, 12.66 kV distribution system with six distributed generations (DGs) in response to various fault scenarios. The simulation results show that the method is robust for single-phase, double-phase, and double-phase to ground faults with high resistance under noisy condition. Furthermore, the method is applicable for networks with inverter interfaced DGs

ADVANCED FAULT AREA IDENTIFICATION AND FAULT LOCATION FOR TRANSMISSION AND DISTRIBUTION SYSTEMS

Fault location reveals the exact information needed for utility crews to timely and promptly perform maintenance and system restoration. Therefore, accurate fault location is a key function in reducing outage time and enhancing power system reliability. Modern power systems are witnessing a trend of integrating more distributed generations (DG) into the grid. DG power outputs may be intermittent and can no longer be treated as constants in fault location method development. DG modeling is also difficult for fault location purpose. Moreover, most existing fault location methods are not applicable to simultaneous faults. To solve the challenges, this dissertation proposes three impedance-based fault location algorithms to pinpoint simultaneous faults for power transmission systems and distribution systems with high penetration of DGs. The proposed fault location algorithms utilize the voltage and/or current phasors that are captured by phasor measurement units. Bus impedance matrix technique is harnessed to establish the relationship between the measurements and unknown simultaneous fault locations. The distinct features of the proposed algorithms are that no fault types and fault resistances are needed to determine the fault locations. In particular, Type I and Type III algorithms do not need the information of source impedances and prefault measurements to locate the faults. Moreover, the effects of shunt capacitance are fully considered to improve fault location accuracy. The proposed algorithms for distribution systems are validated by evaluation studies using Matlab and Simulink SimPowerSystems on a 21 bus distribution system and the modified IEEE 34 node test system. Type II fault location algorithm for transmission systems is applicable to untransposed lines and is validated by simulation studies using EMTP on a 27 bus transmission system. Fault area identification method is proposed to reduce the number of line segments to be examined for fault location. In addition, an optimal fault location method that can identify possible bad measurement is proposed for enhanced fault location estimate. Evaluation studies show that the optimal fault location method is accurate and effective. The proposed algorithms can be integrated into the existing energy management system for enhanced fault management capability for power systems