Compensated Distribution Networks Research Articles

Fault location based on FastICA and fuzzy C-means clustering for single-phase-to-ground fault in the compensated distribution network

Fault location based on FastICA and fuzzy C-means clustering for single-phase-to-ground fault in the compensated distribution network

A hybrid sliding mode control scheme for rapid earth fault current limiters in compensated distribution networks in bushfire prone areas

AbstractA hybrid sliding mode controller is proposed for rapid earth fault current limiters (REFCLs) used in resonant grounded power distribution networks to self‐extinguish powerline bushfires where the concepts of the proportional integral (PI) action and nonsingular fast terminal sliding surface (NFTSS) are combined together to utilize the benefits of both schemes. A hybrid sliding surface is designed for obtaining the control input so that the fault current compensation is achieved by the residual current compensation (RCC) inverter used within a REFCL to a value that the fire does not ignite. The inclusion of an integral action along with the NFTSS helps to significantly reduce the chattering effect. Furthermore, a continuous function is introduced within the proposed scheme to replace the discontinuous signum function. The switches for the RCC inverter are controlled by deriving control actions from the Lyapunov stability theory applied on the hybrid PI‐NFTSS. The performance of the proposed controller is compared with a nonsingular fast terminal sliding mode controller. For this reason, this paper also includes the design process of nonsingular fast terminal sliding mode controller which is designed using only the NFTSS. Simulations under different scenarios having different fault resistances clearly depict the superiority of the proposed scheme over the nonsingular fast terminal sliding mode controller and an existing integral sliding mode controller in terms of maintaining transient responses.

An integral backstepping controller design for compensated distribution networks with rapid earth fault current limiters in bushfire prone areas

This paper presents a nonlinear integral backstepping controller (I-BSC) design scheme for a T-type residual current compensation (RCC) inverter used in compensated distribution networks with rapid earth fault current limiters (REFCLs). The major control task for the proposed scheme is to reduce the fault current to a value suitable for the mitigation of powerline bushfires due to single phase-to-ground faults in compensated distribution networks. The key distinct feature of the proposed I-BSC over the traditional backstepping controller (T-BSC) is that it introduces an integral action for analyzing the dynamic of the tracking error which minimizes its steady-state value and ensures better dynamic performance. In order to prove the global asymptotic stability of the RCC inverter with the proposed integral backstepping controller (I-BSC), the Lyapunov function-based theory is used. Finally, the performance of the I-BSC is analyzed on the MATLAB/Simulink environment and compared with a T-BSC. The performance of both I- and T-BSCs is assessed in terms of transient behaviors of the injected current to the neutral, fault current, and line-to-ground voltage of the faulty phase to ensure the standard operational criteria for self-extinguishing powerline bushfires. Simulation results clearly demonstrate that both controllers fulfill operational standards for REFCL-compensated networks though the I-BSC archives better transient behaviors while comparing with the T-BSC. Results from the processor-in-loop (PIL) validations are also included to further justify the applicability of the newly proposed scheme in the real-time environment.

A non‐singular fast terminal sliding mode control scheme for residual current compensation inverters in compensated distribution networks to mitigate powerline bushfires

This paper presents an approach to design a non-singular fast terminal sliding model controller for residual current compensation inverters in compensated distribution networks to compensate the fault current due to most commonly occurred single line-to-ground faults. The main control objective is to completely eliminate the fault current in order to mitigate the impacts of powerline bushfires. A non-singular fast terminal sliding surface is used to design the controller so that the residual current compensation inverter can quickly ensure the desired control performance without experiencing singularity problems. In this scheme, the chattering effects are minimised by replacing the discontinuous function appearing in the control law with a continuous function and the Lyapunov stability theory is utilised to demonstrate the theoretical stability of the control law. This paper also includes an overview of the non-singular terminal sliding model controller as the performance of the non-singular fast terminal sliding model controller is compared with this controller through rigorous simulation results over a range of fault currents. Simulation results clearly demonstrate the faster convergence speed of the non-singular fast terminal sliding model controller over the non-singular terminal sliding model controller for compensating the fault current and hence, mitigating powerline bushfires.

Effect of Load on Transient Performance of Unearthed and Compensated Distribution Networks

The maximum temperature that cable insulation can withstand determines the maximum load that the cable conductor can carry, which is called cable ampacity. However, a temperature far from this value under normal load conditio... | Find, read and cite all the research you need on Tech Science Press

New method of Arc suppression coil control - increased reliability of power supply in compensated distribution networks

New method of Arc suppression coil control - increased reliability of power supply in compensated distribution networks

A Method for Calculating the Asymmetry in the Shunt Parameters of Power Lines in Compensated Distribution Networks

In compensated distributed networks (CDN), minimizing the asymmetry in the shunt parameters of the power lines is a key factor for avoiding excessive neutral voltages which is necessary not only for safety but also for improving the sensitivity of detecting ground faults, particularly when bush-fire mitigation is a major concern. This paper offers a comprehensive analysis and modeling of the asymmetry of the power lines in CDN. Unlike the existing analyses which assume the asymmetry can be lumped in one phase, the proposed analysis is based on more practical assumption by considering the asymmetry in all of the phases of the power lines. The proposed analysis is used to develop an equivalent circuit for asymmetrical CDN which then used to develop a new method for calculating the per-phase asymmetries in the shunt parameters. The proposed method has been validated based on simulations of real networks.

Faulty Feeder Detection Based on Space Relative Distance for Compensated Distribution Network With IIDG Injections

To improve the accuracy of faulty feeder selection based on zero sequence current mutation, distribution networks with inverter-interfaced distributed generators (IIDGs) are analyzed in detail. It is found that the IIDGs cannot be completely equivalent to a positive sequence current source due to their boosting increments. Thereby, a more accurate IIDG current estimation model based on the Gauss-Seidel method that considers the control strategy at the moment of fault is established. Moreover, a real-time estimation algorithm is introduced for faulty feeder detection to adjust the compensation degree of the Petersen coil. On this basis, this paper proposes a novel faulty feeder detection approach using the zero-sequence current space relative distance between the increments of each feeder and an estimation of the faulty path generated by Kalman filtering (KAF). The feasibility of the proposed approach is demonstrated in both a PSCAD/EMTDC simulation and a MATLAB experimental laboratory. The test results indicate that the proposed approach can achieve a high speed when employed for different fault conditions.

An Additional Criterion for Faulty Feeder Selection During Ground Faults in Compensated Distribution Networks

Identification of faulty feeders and sections during ground faults in compensated medium voltage systems is a complex task demanding development of new methods. Existing steady-state approaches, such as the watt-metric or the admittance based, can be compromised by various parameters of distribution lines or network configuration. Moreover, sensitivity might be threatened during high impedance faults. Transient methods (extensively studied in the recent literature) require thorough analysis before implementation due to their dependency on fault and system parameters. The current paper proposes a new approach for faulty feeder selection during ground faults. It has been tested in the laboratory utilizing electromagnetic transients program (EMTP) simulations. Performance of the developed algorithm has been compared with the conventional steady-state method implemented in a modern feeder relay. The results show improved selectivity and robustness of the new proposed algorithm. Moreover, its applicability for real systems has been demonstrated on fault records obtained from an actual distribution network. The proposed approach can be used as an additional criterion to increase selectivity of the ground fault protection in compensated networks.

Faulty feeder detection by adjusting the compensation degree of arc‐suppression coil for distribution network

A scheme of single-phase-to-ground faulty feeder detection by adjusting the compensation degree of arc-suppression coil (CDASC) for compensated distribution network is presented in this study. The scheme defines transient variation components (TVCs) of feeders, which use the transient signals of zero-sequence current of each feeder and zero-sequence voltage in the bus before the adjustment and those after the adjustment. The TVCs of sound feeders always keep almost 0, while the TVC of faulty feeder changes remarkably before and after adjusting CDASC. On the basis of TVCs, faulty feeder detection can be achieved sensitively and accurately with simple and practicable procedure without sophisticated algorithms. The performance of the scheme validated by digital simulation with various fault conditions of different transition resistances, fault inception angles, white noises and compensation degrees.

Misoperation analysis of steady-state and transient methods on earth fault locating in compensated distribution networks

Abstract Earth fault detection and location are very important issues in distribution networks. Current methods for faulty feeder selection are based on measurements of steady-state or transient signals. The work presented here identifies and gives analyses of scenarios when ground protection based on these methods is prone to misoperation in resonance grounded systems. It is shown that the traditional watt-metric approach can malfunction depending on network and fault parameters. The admittance methods help to eliminate many issues, however they might have complex settings depending on network configurations. Special attention is paid to approaches based on transient signals as the most promising alternative solution. The current work considers methods utilizing zero sequence current, angle, power, energy and admittance transients. The paper reveals limitations for their application mainly due to presence of electrostatic asymmetry, cables in a network, fault resistance and inception angle. Nevertheless, dependability of these methods is higher than the steady-state especially for intermittent faults. It is also found that analysis of prefault information is important both for the steady-state and the transient methods. The obtained results can be used to enhance reliability of protective schemes and as drivers for further developments of new algorithms.

Single-Line-to-Ground Fault Location in the Compensated Distribution Network

One of the most difficult problems in compensated distribution networks is the grounded fault location. This paper proposes a new method for locating single-line-to-ground (SLG) faults in compensated distribution networks. The grounded fault location system is made up of the host, the controller, the signal generator and the grounded fault indicator (GFI). When a SLG fault occurs, the fault phase is identified firstly, and then a signal generator paralleled with the arc suppression coil injects a special current into the system. Subsequently, GFIs along the fault phase are activated to sample the fault phase current and send it back. The fault phase current is computed by the host with a fast Fourier transform algorithm. By comparing these frequency components of the fault phase current, the fault section is identified based on the significant difference of the second harmonic of two adjacent GFIs. Due to the short length of feeders, the distance between two adjacent GFIs is short enough for line patrol personnel to find and repair the fault easily. Finally, a modified IEEE 13-node feeder test is constructed in PSCAD/EMTDC to evaluate this method. The simulations results confirm the validity of the proposed approach.

Single-line-to-ground fault location in the compensated distribution network

Single-line-to-ground fault location in the compensated distribution network

SLG Fault Detection in Presence of Strong Capacitive Currents in Compensated Networks

The detection of a single line-to-ground fault in compensated distribution networks can be hampered by important capacitive currents. The way to deal with this problem depends on the particular regime where data are acquired. In the transient regime, the relays diagnosis based on the analysis of charging components can deceive with a massive presence of discharging currents. The latter, however, will disclose data for directional function if the sampling frequency is high enough for acquisition in the wave propagation area. The fault detection can also be out of reach of steady-state methods which are based on the detection of active components in faulty currents. The efficiency of these methods vanishes when strong capacitive currents squeeze the phase shift between faulty and sound zero-sequence currents below the actual acquisition limits. In such a situation, however, it is still possible to obtain the faulty feeder indication from the way the residual currents cross the zero level soon after inception.

00/00846 Zero sequence directional earth-fault protection with improved characteristics for compensated distribution networks

00/00846 Zero sequence directional earth-fault protection with improved characteristics for compensated distribution networks

Zero sequence directional earth-fault protection with improved characteristics for compensated distribution networks

Selectivity of directional active power (‘wattmetric’) relays for zero sequence earth-fault protection of compensated medium voltage distribution networks is analysed. The analysis is based on estimation of zero sequence steady-state currents in compensated networks. Maloperations caused by imbalance currents of zero sequence current filters are taken into account. A new method to improve the selectivity is proposed.

Service restoration in compensated distribution networks using a hybrid genetic algorithm

In this paper a genetic algorithm (GA) based approach to the service restoration (SR) problem in automated distribution networks is presented. Normal operation within the network comprises both automatic reconfiguration and compensation so as to reduce power losses, allow load balancing and improve the voltage profile. In the restorative state, the reconfiguration is performed together with compensation, taking mainly into account the load supply requirement and secondarily, the losses reduction requirement. After a general discussion on the restoration problem together with a short review of recent papers on the topic, a solution strategy is proposed. Then, a short account about classical GA searching mechanism is reported in order to emphasize the difficulties arising from the application of a classical GA to the restoration problem. Therefore, the hybridization strategy of the GA is presented in depth, with particular regard to the description of some new operators, of the objective function and of the constraints expression. Finally, test results and concluding remarks are reported.