Single-phase Short-circuit Fault Research Articles

Online Full Range Copper Loss Minimization for Single-Phase Short-Circuit Fault Tolerant Control in Five-Phase PMSM

Online Full Range Copper Loss Minimization for Single-Phase Short-Circuit Fault Tolerant Control in Five-Phase PMSM

A Section Location Method of Single-Phase Short-Circuit Faults for Distribution Networks Containing Distributed Generators Based on Fusion Fault Confidence of Short-Circuit Current Vectors

A Section Location Method of Single-Phase Short-Circuit Faults for Distribution Networks Containing Distributed Generators Based on Fusion Fault Confidence of Short-Circuit Current Vectors

A parameter-free fault location method for cross-bonding cable based on ranging equations

With the increasing application of long-distance high-voltage cables using the cross-bonding grounding method in urban power grids, the effectiveness and accuracy of the single-phase short-circuit fault location method for cross-bonded cables have gradually gained attention. To reduce positioning errors caused by inaccurate or unknown line parameters, a fault location method independent of line parameters is proposed. Firstly, the changes in sheath circulating current before and after the fault occurrence are analyzed, and based on these changes, a criterion for fault identification is established to determine the approximate range of fault occurrence. Secondly, considering the three-phase electromagnetic coupling of cross-bonded cables, an equivalent model for single-phase short-circuit faults in cross-bonded cables is established based on the double-π model. The along-line voltage and current are calculated by deducing electrical quantities at the ends of the cable. Then, the fault location equations are formulated based on the fault section, and the trust-region algorithm is employed to solve for fault distances and unit-length parameters of the cable in each equation group. Finally, a cable fault model is built using the PSCAD/EMTDC simulation platform, and the influence of different factors on the fault location method is analyzed. The results show that the fault location error of the proposed method is around 0.2 %, demonstrating high accuracy.

Single-Phase Short-Circuit Fault Tolerant Control for Five-Phase Permanent Magnet Machines With Copper Loss Reduction

Single-Phase Short-Circuit Fault Tolerant Control for Five-Phase Permanent Magnet Machines With Copper Loss Reduction

Influence of Rotor Damping Bars on Rotor Temperature Rise of Synchronous Condenser After Single-Phase Short-Circuit Fault

A synchronous condenser (SC) can provide the transient reactive power support for the Ultra High Voltage Direct Current (UHVDC) converter station. However, the rotor temperature rise is generally the main factor which limits the transient operation ability of the SC. In this paper, a rotor structure of the SC with the rotor damping bars made of different materials in the rotor large teeth is proposed to reduce the rotor temperature rise. In order to obtain the influence of the rotor damping bars on the temperature rise, the rotor loss and temperature distribution of a 300-MVar SC under the single-phase short-circuit fault are calculated by coupling the electromagnetic field, loss and temperature field models of the SC with the model of the power grid. For the damping bars made of the copper, aluminum and stainless steel, the rotor maximum temperature rises are calculated and compared. According to the maximum permissible temperature of the rotor core, the transient operating ability of the SC with the rotor damping bars made of different materials is obtained under the single-phase short-circuit fault. This study can provide the theoretic basis for the improvement of the transient reactive power support capacity of the SC under the single-phase short-circuit fault.

SHORT CIRCUIT FAULT ANALYSIS IN THE ELECTRIC POWER DISTRIBUTION SYSTEM AT PT PLN (Persero) UP3 SOUTH MAKASSAR ULP KALEBAJENG USING ETAP

Short circuit fault analysis is needed to determine the amount of short circuit current flowing in a system. This study discusses the single-phase short-circuit current to the ground at the point where the disturbance occurs from the base of the network to the end of the Malewang feeder network. The purpose of this study was to determine the amount of short circuit fault current in the Electric Power Distribution System at PT PLN (Persero) UP3 South Makassar ULP Kalebajeng. This study used the ETAP program and manual calculations. The results of the study found that the contribution of the largest single-phase short-circuit fault current to the ground in the Malewang feeder occurred on Buses located at the base of the network close to the Substation, namely Bus 1 (Exim-Rec Kalaserena) of 0.311 kA, while thesmallest Buscontribution occurred on Buses located at the end of the network far from the Substation, namely Buses 14 (Bilonga) of 0.292 kA. From the results of the study, it can be concluded that the farther the interference bus is from the Substation, the greater the channel impedance. The greater the impedance, the smaller the short-circuit current.

An Optimized Active Power Backflow Suppression Strategy for Cascaded H-Bridge PV Grid-Connected Inverter During Inter-Phase Short-Circuit Fault

Active power backflow is a unique problem of three-phase isolated cascaded H-bridge (CHB) PV inverter during asymmetric grid voltage fault, resulting in the continuous rise of H-bridge dc-bus voltages and that the inverter will be eventually shut down and off-grid due to voltage out of control. The existing methods are able to completely suppress the active power backflow during single-phase short-circuit fault and two-phase short-circuit fault, but fails in a large operating zone when inter-phase short-circuit fault occurs. For this issue, this paper proposes a novel multiple specific harmonic voltages injection method based on the existing fundamental-frequency zero-sequence voltage compensation strategy, which calculates and injects the optimal third, fifth, seventh and ninth harmonic voltage according to the fault type, drop depth and the normalized power, for minimizing the amplitude of three-phase modulation voltages and then significantly shrinking active power backflow zone of three-phase isolated CHB PV inverter. Then, the area of the active power backflow zones for different control methods is quantitatively calculated and compared by adopting the polynomial fitting to show the advantages of the proposed method. Finally, experimental results are achieved by a low voltage and low power experimental prototype to verify its effectiveness and feasibility.

An Optimized LVRT Control Strategy of Cascaded Modular Medium-Voltage Inverter for Large-Scale PV Power Plant

Active power backflow is an inherent problem of three-phase cascaded H-bridge (CHB) photovoltaic (PV) grid-tied inverters during low-voltage ride through (LVRT), probably resulting in no balanced operating point of the system, and the inverter will be shut down and off-grid due to overvoltage fault. Aiming at this issue, this article first reviews the existing control methods and analyzes their limitations in application, that is, they cannot effectively suppress active power backflow under the scenario of deeper voltage drop and lower output power. On this basis, an optimized LVRT control strategy for cascaded modular medium-voltage PV power generation system is proposed, which adopts different control methods to suppress active power backflow under three types of asymmetric grid drop conditions: single-phase short-circuit fault with ground, two-phase short-circuit fault with ground, and two-phase short-circuit fault without ground, enhancing the adaptability of CHB PV grid-connected inverters to different output powers and different drop depths during grid voltage failure and then improving LVRT capability of the system. Finally, the effectiveness and feasibility of the proposed control strategy are verified by experimental results.

Neutral Voltage Modeling and Its Remediation for Five-Phase PMSMs Under Single-Phase Short-Circuit Fault Tolerant Control

Field-oriented control (FOC) still serves as an advanced way to control ac motors for industrial applications, as such, this technique is being expanded to the postfault operation of five-phase permanent magnet synchronous motors ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\Phi $ </tex-math></inline-formula> -PMSMs) under phase fault conditions. Previous articles have proved that the motor’s neutral voltage (NV) oscillates over the dc-bus midpoint under a single-phase open-circuit fault (OCF), and NV remediation is needed for the successful fault-tolerant FOC. However, regarding the short-circuit faults (SCFs), neither the NV model nor its remediation is elaborated. The NV oscillates severely under SCFs, and it deserves an in-depth understanding for better making use of this faulty drive. To this end, this work establishes an NV model for a general <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\Phi $ </tex-math></inline-formula> -PMSM under the single-phase SCFs, including interturn and ground SCFs, and an NV remedial rule is, therefore, provided to rectify the phase voltage modulation that forms the basis of an inverter-driven system. In addition, the presented rule requires little knowledge of the motor parameters, and it can also be very easy to implement. Finally, the experimental and simulation results confirm the validity of the presented NV model as well as its remedial method.

Rotor Loss and Temperature Field of Synchronous Condenser Under Single-Phase Short-Circuit Fault Affected by Different Materials of Rotor Slot Wedge

A synchronous condenser (SC) can provide the dynamic reactive power for the ultra-high-voltage direct current converter station during the system voltage drop caused by the single-phase short-circuit fault, which is one of the prevalent faults. However, the single-phase short-circuit fault can also result in the increase of the rotor loss and temperature and thus restrict the transient operating ability of the SC. A key factor that affects the rotor loss and temperature rise is the material of the rotor slot wedges. For a 300-MVar SC with the rotor slot wedges made of the aluminum, beryllium bronze, and stainless steel, the rotor loss and temperature distribution under the single-phase short-circuit are calculated by coupling the electromagnetic and temperature field models of the SC with the models of the power grid. The variations of the rotor losses along with the rotor slot wedge conductivity are revealed. The rotor regions, where the highest temperature rise appears, are obtained. According to the maximum permissible temperature of the rotor material, the transient operating ability of the SC withstanding the single-phase short-circuit fault is obtained. This article can provide the theoretic basis for improving the transient operating ability of the SC.

A machine learning-based fault identification method for microgrids with distributed generations

The development of renewable energy sources such as solar and wind based on distributed generators are growing rapidly in the face of the global energy crisis. As a connection between distributed generation and the main grid, microgrids are also growing rapidly. However, due to the randomness and uncertainty of the output of the solar and wind power, as well as the bidirectional characteristic of current flow, the faults in microgrids are difficult to identify using the traditional fault detection methods. To address this problem, this paper proposes a machine learning-based fault identification method for microgrids. First, the modified K-means algorithm is implemented to cluster the voltage data. Then, FP-growth algorithm is using to extract the association rules. Third, the mini-batch gradient descent (MBGD) algorithm is using to train the fault identification model based on machine learning theory. To verify the validity of this method, a case study considering single-phase short-circuit fault and two-phase phase short-circuit fault is simulated. The method presented in this work is with a high accuracy according to the simulation results.

Remedy Strategy for Five-Phase FTPMMs Under Single-Phase Short-Circuit Fault by Injecting Harmonic Currents From Third Space

This article proposes a new fault-tolerant control for five-phase fault-tolerant permanent-magnet motors under single-phase short-circuit fault. In the proposed method, the effect on torque performance caused by a short-circuit fault is attributed into two parts: the loss of the short-circuited phase, which is equivalent to a phase open-circuit fault, and the resultant short-circuit current. The remedial action for loss of a phase is realized in the fundamental space, while the torque ripple caused by the short-circuit current is compensated by the harmonic currents in the third space. To decouple the control of the fundamental and third space, the reduced-order Clarke and Park transformation matrixes for the two spaces are obtained separately under single-phase short-circuit fault. Afterward, the fundamental currents with minimum joule losses or equal joule losses for loss of a phase, and the harmonic currents in the third space for torque ripple reduction are derived. Hence, the proposed method can realize torque ripple-free operation under single-phase short-circuit fault. Finally, the effectiveness of the proposed method is verified by experimental results under various operational conditions.

Analisis Penentuan Lokasi Gangguan Hubung Singkat Pada Saluran Transmisi Di Sulawesi Tenggara

The electricity system often experiences disturbances, especially short circuit disturbances on transmission lines. This short circuit disturbance is caused by various things such as lightning surges, fallen trees, animals, and other conditions. The interconnected Southeast Sulawesi power system cannot be separated from this short circuit problem. Therefore, determining the location of this short-circuit fault must be done quickly so that the cause of the disturbance can be immediately identified. This study aims to analyze the determination of the location of short circuit faults using the Takagi Method. Simulations were carried out using ETAP 16.0.0 software to see the condition of the Southeast Sulawesi system power flow. This Takagi method analyzes the location of the disturbance using the conditions before and after the disturbance occurs based on the recorded data at the substation. The results of the analysis carried out on the Southeast Sulawesi transmission line show that the percentage of accuracy in determining the location of a single-phase short-circuit fault to ground using the Takagi method is better, with a distance difference of 0.368-0.581 km (1.49%) when compared to the reading results on recordings of 10,173-9,960 km (31.58%) from the fault location occurred after inspection of the Lasusua-Kolaka transmission line. Disturbances on lines 1 and 2 Kolaka-Lasusua produce an error value of 1.533 km (9.24%) and 1.547 km (9.32%) when compared to fault locator readings of 3.212 km (19.36%) and 1.812 km ( 10.92%). Meanwhile, the Unaaha-Kolaka transmission line produces a distance difference of 0.709 km (3.29%) when compared to the fault locator reading of 4.323 km (20.12%). The results of the power flow simulation produce an installed generating capacity of 188 MW, a total active power of 116.780 MW and a reactive power of 29,944 Mvar. Thus, it can be concluded that the Takagi Method has a better accuracy value in reading fault locators.

Rotor Loss and Thermal Analysis of Synchronous Condenser Under Single-Phase Short-Circuit Fault in the Transmission Line

A synchronous condenser (SC) can provide the reactive power for the Ultra High Voltage Direct Current (UHVDC) converter station to keep voltage stability and prevent commutation failure. The single-phase short circuit at a transmission line is prevalent and it can result in not only the voltage drop but also the increase of the rotor loss and temperature of the SC. In order to study the ability of the SC to withstand a single-phase short-circuit fault, the rotor loss and temperature field of a 300-MVar SC are studied by coupling the electromagnetic and temperature field models of the SC with the models of the electric circuit and power grid. The loss distributions in the rotor core and slot wedges are calculated under a single-phase short-circuit fault at the different positions of the transmission line. The rotor temperature distributions of the SC under over- and under-excitations are calculated and verified by the experiments. The influence of short-circuit duration on the rotor temperature of the SC is calculated under the single-phase short circuit. The study can provide a theoretic basis for the improvement of the operating ability of the SC under the single-phase short-circuit faults.

Multivectors Model Predictive Control With Voltage Error Tracking for Five-Phase PMSM Short-Circuit Fault-Tolerant Operation

Model predictive control (MPC) has been successfully extended into fault-tolerant operation for the five-phase permanent-magnet synchronous motor (PMSM) under an open-circuit fault. However, compared with the open-circuit fault, the influence of short-circuit fault is more serious. Therefore, this article proposes a new multivectors model predictive control (MV-MPC) with voltage error tracking for a five-phase PMSM under short-circuit faults, including single-phase short-circuit fault and interphase short-circuit fault. The key of this method is to directly add short-circuit compensatory currents to reference currents that benefited from the advantages of MPC. Due to the loss of the faulted phase, the shapes of ordinary sectors under faults become asymmetrical. Then, a multivectors selection method is presented by constructing the cost function with voltage error terms and determining optimal vectors based on the shortest distance principle and sine theorem. Compared with the existing methods, the total harmonic distortion of the current and torque ripple is reduced greatly under the proposed method. Finally, the effectiveness and superiority of the proposed method are validated by experiments.

Research on transient stability control method for LCC‐HVDC receiving‐end system based on the gradient of dynamic energy

A new transient stability control strategy for the Line-Commutated-Converter based High-Voltage-Direct-Current (LCC-HVDC) receiving-end system based on the gradient of dynamic energy is proposed to deal with this problem. Firstly, in the whole process from fault occurrence to fault removal, a dynamic energy function representing the stability of the system is constructed. On this basis, considering the influence of Direct Current (DC) inverter side controller, the dynamic energy gradient expression under three-phase and single-phase short-circuit fault scenarios is deduced in detail. The influence of control parameters on dynamic energy accumulation or consumption is analytically described. Then, the function term related to the inverter side controller is extracted from the dynamic energy gradient expression, the trigger pulse on the inverter side is controlled to keep the dynamic energy gradient of the DC port at the minimum. Finally, the hardware in the loop test is carried out on RT-LAB. The test results show that in the process of receiving end fault, the DC port will inject dynamic energy to the receiving end system, making the system tend to be unstable. This method is able to reduce the dynamic energy accumulation rate of system and increase the critical clearing time of system.

Transients in a 20 kV Network Due to Single-Phase Short-Circuit Faults in 220 kV Cable Lines

The transient processes in a 20 kV network due to single-phase short circuit fault in the 220 kV lines of a 220/20 kV supply substation are considered. Combinations of parameters at which overvoltages are the highest are determined. The overvoltages limited by surge arresters installed on 20 kV busbars are estimated.

Predictive Duty Cycle Control for Four-Leg Inverters With ${LC}$ Output Filter

Three-phase four-leg inverter is a well-known solution to handle unbalanced and nonlinear loading conditions in three-phase transformerless uninterruptible power supply applications. For such power converters, finite control set model predictive control (FCS-MPC) is considered as a promising control alternative due to its simplicity, fast dynamic response, and capability to include nonlinearities and constraints. However, the absence of modulator in FCS-MPC implementation leads to several shortcomings, such as higher load voltage total harmonic distortion (THD), large tracking error of control objectives, and variable switching frequency. Furthermore, the fourth leg operates with a higher average switching frequency than the other three main legs, which complicates the $LC$ filter design. To overcome the aforementioned shortcomings, a new predictive duty cycle control is proposed in this article. Extensive experimental results are shown to verify that the proposed method can achieve enhanced steady-state performance with significant reduced load voltage THD and tracking error under different operating conditions, such as nonlinear single-/three-phase unbalanced load and single-phase short-circuit fault, while preserving the fast dynamic performance of FCS-MPC. Steady-state and dynamic performances of the proposed method are compared to FCS-MPC and double-vector MPC approaches to validate the superiority of the proposed scheme.

Practical Calculation Method for the Short-Circuit Current of Power Grids with High Temperature Superconducting Fault Current Limiters

With the expansion of the power grid scale and the enhancement of network structure interconnection, the short-circuit current of power grids is increasingly close to the upper capacity limit of circuit breakers. The fault current limiter is effective in suppressing the short-circuit current of power grids, and with the mature development of superconducting technology, high-temperature superconducting fault current limiters (HTS-FCLs) have been widely used in power grids. Due to the nonlinear impedance–current characteristic of HTS-FCLs, the traditional short-circuit current calculation method is inapplicable to power grids with HTS-FCLs. First, based on the establishment of the electromechanical transient model and the short-circuit calculation model, the short-circuit current calculation procedure for power grids with HTS-FCLs is proposed. Second, the calculation methods for three-phase and single-phase short-circuit currents at the substation bus in power grids with HTS-FCLs are analyzed. Finally, three-phase and single-phase short-circuit currents at the 500 kV Xijiang substation bus in the Guangdong power grid are calculated as the study case. Simulation results show that compared with the situation where there is no HTS-FCL installed, the short-circuit current on the 500 kV bus decreases from 65.34 to 58.31 kA in terms of the three-phase short-circuit fault, and decreases from 54.56 to 46.62 kA in terms of the single-phase short-circuit fault, thus verifying the effectiveness and practicability of HTS-FCLs in suppressing the short-circuit current, which is significant for the safe, stable and reliable operation of the power grid.

Impact of wind power grid connection and interline short circuit faults on power grid

With the gradual increase of electricity demand in China, wind power and other power generation has developed rapidly, which makes the structure of power grid more complex. The complex structure increases the risk of short-circuit fault of power grid. The rapid development of wind power intensifies the randomness of power grid operation. This paper uses MATLAB/Simulink to model power system, construct simulation, and analyse the influence of grid-connected wind power and short-circuit faults on grid stability. The results show that the fluctuation and impact of the active power on the user side are significantly weakened compared with those of the single wind power grid when the high-power stable power supply is connected to the wind power grid. The single-phase short-circuit fault has no disturbance to the user of the grid, and the two-phase short-circuit and three-phase short-circuit have greater impact on the voltage, current and speed of the user end.