scholarly journals Probabilistic Short-Circuit Current in Active Distribution Networks Considering Low Voltage Ride-Through of Photovoltaic Generation

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 140071-140083
Author(s):  
Weiyan Qian ◽  
Niancheng Zhou ◽  
Jiafang Wu ◽  
Yuze Li ◽  
Qianggang Wang ◽  
...  
Keyword(s):  
Low Voltage ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distribution Networks ◽  
Photovoltaic Generation ◽  
Low Voltage Ride Through ◽  
Active Distribution Networks

scholarly journals A Novel Machine Learning-Based Short-Circuit Current Prediction Method for Active Distribution Networks

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3793 ◽  
Author(s):  
Zheng ◽  
Wang ◽  
Jiang ◽  
He
Keyword(s):  
Distribution Systems ◽  
Large Scale ◽  
Short Circuit ◽  
Distribution Network ◽  
Prediction Method ◽  
Short Circuit Current ◽  
Distribution Networks ◽  
Test System ◽  
High Penetration ◽  
Active Distribution Networks

The traditional mechanism models used in short-circuit current calculations have shortcomings in terms of accuracy and speed for distribution systems with inverter-interfaced distributed generators (IIDGs). Faced with this issue, this paper proposes a novel data-driven short-circuit current prediction method for active distribution systems. This method can be used to accurately predict the short-circuit current flowing through a specified measurement point when a fault occurs at any position in the distribution network. By analyzing the features related to the short-circuit current in active distribution networks, feature combination is introduced to reflect the short-circuit current. Specifically, the short-circuit current where IIDGs are not connected into the system is treated as the key feature. The accuracy and efficiency of the proposed method are verified using the IEEE 34-node test system. The requirement of the sample sizes for distribution systems of different scale is further analyzed by using the additional IEEE 13-node and 69-node test systems. The applicability of the proposed method in large-scale distribution network with high penetration of IIDGs is verified as well.

scholarly journals Research on Theoretical Calculation Methods of Photovoltaic Power Short-Circuit Current and Influencing Factors of Its Fault Characteristics

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 316 ◽  
Author(s):  
Huiyuan Liu ◽  
Kehan Xu ◽  
Zhe Zhang ◽  
Wei Liu ◽  
Jianyong Ao
Keyword(s):  
Theoretical Calculation ◽  
Low Voltage ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Calculation Model ◽  
Load Level ◽  
Low Voltage Ride Through ◽  
Complex Fault ◽  
Power Load ◽  
Bus Voltage

With the substantial increase in the capacity of grid-connected photovoltaic (PV) power, the adverse effects of its complex fault characteristics on grid relay protection are increasingly highlighted. Based on the introduction of the topology and the control strategy on low-voltage ride through of PV power, a theoretical solution method for solving the fault current of PV power is proposed by taking account of the DC bus voltage fluctuation, and a theoretical calculation model of its transient and steady state is established. The correctness of the theoretical results is verified by the numerical simulation results and low-voltage ride through (LVRT) experiment results. Furthermore, to gain a better understanding of the factors influencing PV power fault characteristics, the effects of several factors including proportional integral (PI) controller parameters, fault voltage sag depth, and PV power load level on PV power fault characteristics are analyzed by using simple variable method. The obtained results can provide a theoretical reference for the control parameter design and protection research of PV power.

scholarly journals Practical calculation of asymmetric short circuit current of DFIG connected to distribution network

2020 ◽  
Vol 145 ◽  
pp. 02075
Author(s):  
Pengwu Fu ◽  
Dongwen Yang ◽  
Zhi He ◽  
Zhenfeng Duan ◽  
Dengmei Wang
Keyword(s):  
Low Voltage ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Equivalent Model ◽  
Practical Calculation ◽  
Negative Sequence ◽  
Low Voltage Ride Through ◽  
Periodic Components ◽  
Engineering Projects

In view of the existing complex analytic calculations of DFIG short-circuit current are hardly applied in engineering projects, a practical calculation of asymmetric short-circuit current of DFIG is proposed. According to the complex sequence and their Thevenin equivalent model of DFIG network, the composition of each sequence component of DFIG short-circuit current is analysed. Moreover, considering the low-voltage ride through strategy of DFIG, the negative sequence periodic components of short circuit current are well analysed during the crowbar activation and deactivation, and the formula of the negative sequence periodic components of short circuit current are derived. On the basis of positive and negative sequence open circuit voltage, calculating impedance and rotor current, the judgement of crowbar activation is established. The pre-calculated surfaces of negative sequence periodic components of short circuit current are proposed, and the procedure for calculating the asymmetric short-circuit current of DFIG is designed. Finally, the proposed method is verified by simulation.

scholarly journals Thermal Analysis of Heat Distribution in Busbars during Rated Current Flow in Low-Voltage Industrial Switchgear

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2427
Author(s):  
Michał Szulborski ◽  
Sebastian Łapczyński ◽  
Łukasz Kolimas
Keyword(s):  
Structural Changes ◽  
Heat Dissipation ◽  
Current Flow ◽  
Low Voltage ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Coupled Analysis ◽  
Precise Representation ◽  
Transient Thermal ◽  
Halogen Free

The manuscript presents advanced coupled analysis: Maxwell 3D, Transient Thermal and Fluent CFD, at the time of a rated current occurring on the main busbars in the low-voltage switchgear. The simulations were procured in order to aid the design process of such enclosures. The analysis presented the rated current flow in the switchgear busbars, which allowed determining their temperature values. The main assumption of the simulation was measurements of temperature rise during rated current conditions. Simulating such conditions is a valuable asset in order to design better solutions for energy distribution gear. The simulation model was a precise representation of the actual prototype of the switchgear. Simulations results were validated by experimental research. The heat dissipation in busbars and switchgear housing through air convection was presented. The temperature distribution for the insulators in the rail bridge made of fireproof material was considered: halogen-free polyester. The results obtained during the simulation allowed for a detailed analysis of switchgear design and proper conclusions in practical and theoretical aspects. That helped in introducing structural changes in the prepared prototype of the switchgear at the design and construction stages. Deep analysis of the simulation results allowed for the development concerning the final prototype of the switchgear, which could be subjected to the full type tests. Additionally, short-circuit current simulations were procured and presented.

scholarly journals Cheap Conic OPF Models for Low-Voltage Active Distribution Networks

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 99691-99708
Author(s):  
Muhammad Usman ◽  
Andrea Cervi ◽  
Massimilano Coppo ◽  
Fabio Bignucolo ◽  
Roberto Turri
Keyword(s):  
Low Voltage ◽  
Distribution Networks ◽  
Active Distribution Networks

scholarly journals Accurate Assessment of Decoupled OLTC Transformers to Optimize the Operation of Low-Voltage Networks

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2173
Author(s):  
Álvaro Rodríguez del Nozal ◽  
Esther Romero-Ramos ◽  
Ángel Luis Trigo-García
Keyword(s):  
Distributed Generation ◽  
Optimization Problem ◽  
Low Voltage ◽  
Optimal Solution ◽  
Distribution Networks ◽  
Voltage Regulation ◽  
Rigorous Approach ◽  
Tap Changer ◽  
Load Tap Changer ◽  
Active Distribution Networks

Voltage control in active distribution networks must adapt to the unbalanced nature of most of these systems, and this requirement becomes even more apparent at low voltage levels. The use of transformers with on-load tap changers is gaining popularity, and those that allow different tap positions for each of the three phases of the transformer are the most promising. This work tackles the exact approach to the voltage optimization problem of active low-voltage networks when transformers with on-load tap changers are available. A very rigorous approach to the electrical model of all the involved components is used, and common approaches proposed in the literature are avoided. The main aim of the paper is twofold: to demonstrate the importance of being very rigorous in the electrical modeling of all the components to operate in a secure and effective way and to show the greater effectiveness of the decoupled on-load tap changer over the usual on-load tap changer in the voltage regulation problem. A low-voltage benchmark network under different load and distributed generation scenarios is tested with the proposed exact optimal solution to demonstrate its feasibility.

scholarly journals Online Estimation of Short-Circuit Fault Level in Active Distribution Network

2020 ◽  
Vol 10 (11) ◽  
pp. 3812
Author(s):  
Xiaohui Wang ◽  
Peng Wang ◽  
Yunbo Wang ◽  
Fang Shi
Keyword(s):  
Equivalent Circuit ◽  
Short Circuit ◽  
Distribution Network ◽  
Estimation Method ◽  
Short Circuit Current ◽  
Distribution Networks ◽  
Measurement Unit ◽  
Online Estimation ◽  
Active Distribution Network ◽  
Short Circuit Fault

The potential short-circuit current in active distribution network features time-variance with the increasing distributed generations. This feature makes the online estimation of fault level necessary. In this paper, a novel online estimation method is proposed to be implemented by either phasor measurement unit (PMU) or the measurements from protection relays. The equivalent circuit of the radial distribution network with distributed generators (DGs), e.g., wind turbines and photovoltaic cells, is derived with necessary simplifications. The natural disturbances downstream are used to evaluate the parameters of the equivalent circuit so that the potential fault level can be estimated in advance of the actual fault occurrence. A fuzzy logic identifier is presented to rank the confidence of the measurements incurred by the disturbance and to distinguish the qualified disturbance to launch the estimation. The mechanism based on multi-measurements and confidence indices was applied, to improve the accuracy. A typical distribution network in the United Kingdom (UK) with DGs was taken, as an example, to validate the proposed method under various load fluctuation. The results confirm the effectiveness of the proposed method, which is suitable for online estimation of short-circuit fault level in active distribution networks.

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