scholarly journals Power-Based Concept for Current Injection by Inverter-Interfaced Distributed Generations during Transmission-Network Faults

2021 ◽  
Vol 11 (21) ◽  
pp. 10437
Author(s):  
Boštjan Polajžer ◽  
Bojan Grčar ◽  
Jernej Černelič ◽  
Jožef Ritonja
Keyword(s):  
Network Topology ◽  
Reactive Power ◽  
Short Circuit ◽  
Current Injection ◽  
Fault Current ◽  
Transmission Network ◽  
Transmission Networks ◽  
Distributed Generations ◽  
Grid Codes ◽  
Radial Network

This paper analyzes the influence of inverter-interfaced distributed generations’ (IIDGs) response during transmission network faults. The simplest and safest solution is to switch IIDGs off during network faults without impacting the network voltages. A more elaborate and efficient concept, required by national grid codes, is based on controlling the IIDGs’ currents, involving positive- and negative-sequence voltage measured at the connection point. In this way the magnitude and phase of the injected currents can be adjusted, although the generated power will depend on the actual line voltages at the connection point. Therefore, an improved concept is proposed to adjust IIDGs’ fault current injection through the required active and reactive power, employing the same voltage characteristics. The proposed, i.e., power-based concept, is more definite than the current-based one, since the required power will always be generated. The discussed concepts for the fault current injection by IIDGs were tested in different 110-kV networks with loop and radial topologies, and for different short-circuit capabilities of the aggregated network supply. Based on extensive numerical calculations, the power-based concept during transmission networks faults generates more reactive power compared to the current-based concept. However, the voltage support by IIDGs during transmission networks faults, regardless of the concept being used, is influenced mainly by the short-circuit capability of the aggregated network supply. As regards distance protection operation, it is influenced additionally by the network topology, i.e., in radial network topology, the remote relay’s operation can be delayed due to a largely seen impedance.

scholarly journals Tansient fault analysis of a VSC-based multi-terminal HVDC scheme

2020 ◽  
Author(s):  
◽  
Sindisiwe Cindy Malanda
Keyword(s):  
High Voltage ◽  
Direct Current ◽  
Reactive Power ◽  
Short Circuit ◽  
Critical Time ◽  
Fault Analysis ◽  
Fault Current ◽  
Dc Voltage ◽  
High Voltage Direct Current ◽  
Ground Fault

A multiterminal HVDC system includes the connection of different HVDC terminals to a common grid. Most of the MTDC networks are realized in voltage source converter (VSC) high voltage direct current (HVDC). Over long distances, HVDC transmission is preferred to high voltage direct current (HVAC). Furthermore, HVDC is subjected to minimal harmonics oscillation problems due to the absence of frequency. HVDC enables the interconnection of systems at different frequencies, and the system becomes free of angular stability problems. VSCs employ insulated gate bipolar transistors (IGBTs) switches, and High-frequency pulse width modulation is used to operate the IGBTs in order to achieve high-speed control of active and reactive power. The growth of MTDC networks may require a new type of VSCs topology, which is resilient and efficient to dc and ac network fault. This research investigation focuses on the transient dc-side fault analysis in a two-level Monopolar VSC- Based Multi-Terminal HVDC Scheme consisting of four asynchronous terminals sharing a rated 400kV DC-grid was carried out in PSCAD software. During dc-side fault analysis, a pole-to-ground fault was taken into consideration as it’s more likely to occur, although it is less severe compared to pole-to-pole. The converters are interconnected through 100 km dc cables placed 0.5 gm apart and at a depth of 1.5 m underground. It was observed that during the steady-state analysis, the dc voltage in the grid was maintained at the rated value 400 kV, the currents measured at the converters bus was 0.5 kA, and the current flowing through the cables was 0.25 kA. Under the fault condition, the dc voltage drop needs to be maintained to a closed range to avoid the grid to collapse. The voltage droop technique was incorporated in the dc voltage controller to keep the dc voltage at the narrow range. Depending on the value and nature of ground fault resistance, the fault current magnitude varies, and distance variation along the cable has a significant contribution in the fault current. It is observed that fault close to the converter (5 km’s measured 9 kA) results in high fault currents compared to fault away from the converter (50 km’s measured 7.8 kA). The protection design of the VSC needs to be able to detect whether its ground fault or short circuit since the location of the fault needs to be identified and repaired. Another observation made when the fault is inserted 50 kms away from the converter, meaning the fault is at the center of the two converters, the outcome results in high currents in both converters. The isolation of the fault should be fast and selective as the critical time is very short. The dc circuit breakers are mostly recommended to be used as primary protection; however, different protection techniques need to be incorporated with dc circuit breaker in order to quickly identify, select and reliable isolate the faulted line. Moreover, the protection should be able to isolate the line before the fault reaches the maximum fault current to avoid the damage in the converter components.

scholarly journals SFCL-SMES Control for Power System Transient Stability Enhancement Including SCIG-based Wind Generators

2020 ◽  
Vol 10 (2) ◽  
pp. 5477-5482
Author(s):  
A. Zebar ◽  
L. Madani
Keyword(s):  
Power System ◽  
Wind Energy ◽  
Voltage Stability ◽  
Reactive Power ◽  
Short Circuit ◽  
Renewable Energy Sources ◽  
Test System ◽  
Fault Current ◽  
Combined Model ◽  
Induction Generators

The resolution of the environment pollution depends on renewable energy sources, such as wind energy systems. These systems face transient and voltage stability issues with wind energy employing fixed-speed induction generators to be augmented with resistive type Superconducting Fault Current Limiter (SFCL) and Superconducting Magnetic Energy Storage (SMES) devices. The use of a combined model based on SFCL and SMES for promoting transient and voltage stability of a multi-machine power system considering the fixed-speed induction generators is the primary focus of this study. Our contribution is the development of a new model that combines the advantages of SFCL and SMES. The proposed model functions assure flexible control of reactive power using SMES controller while reducing fault current using superconducting technology-based SFCL. The effectiveness of the proposed combined model is tested on the IEEE11-bus test system applied to the case of a three-phase short circuit fault in one transmission line.

scholarly journals Design of Capacitive Bridge Fault Current Limiter for Low-Voltage Ride-Through Capacity Enrichment of Doubly Fed Induction Generator-Based Wind Farm

2021 ◽  
Vol 13 (12) ◽  
pp. 6656
Author(s):  
A. Padmaja ◽  
Allusivala Shanmukh ◽  
Siva Subrahmanyam Mendu ◽  
Ramesh Devarapalli ◽  
Javier Serrano González ◽  
...  
Keyword(s):  
Wind Farm ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Drop ◽  
Short Circuit ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Low Voltage Ride Through ◽  
Current Limiter ◽  
Doubly Fed

The increase in penetration of wind farms operating with doubly fed induction generators (DFIG) results in stability issues such as voltage dips and high short circuit currents in the case of faults. To overcome these issues, and to achieve reliable and sustainable power from an uncertain wind source, fault current limiters (FCL) are incorporated. This work focuses on limiting the short circuit current level and fulfilling the reactive power compensation of a DFIG wind farm using a capacitive bridge fault current limiter (CBFCL). To deliver sustainable wind power to the grid, a fuzzy-based CBFCL is designed for generating optimal reactive power to suppress the instantaneous voltage drop during the fault and in the recovery state. The performance of the proposed fuzzy-based CBFCL is presented under a fault condition to account for real-time conditions. The results show that the proposed fuzzy-based CBFCL offers a more effective solution for overcoming the low voltage ride through (LVRT) problem than a traditional controller.

scholarly journals Potential of Slip Synchronous Wind Turbine Systems: Grid Support and Mechanical Load Mitigation

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4995
Author(s):  
Dillan Kyle Ockhuis ◽  
Maarten Kamper
Keyword(s):  
Wind Turbine ◽  
Dynamic Stability ◽  
High Speed ◽  
Reactive Power ◽  
Low Voltage ◽  
Mechanical Load ◽  
Short Circuit ◽  
Power Converter ◽  
Grid Services ◽  
Grid Codes

Wind power penetration into existing electrical power systems continues to experience year-on-year growth. Consequently, modern wind turbine systems (WTS) are required to comply with relevant grid codes and provide ancillary grid services to assist with overall grid stability. Adhering to these grid codes and services can cause additional mechanical loading on WTS, which can result in a reduction in service life of some of the drivetrain components, and instability if a sufficient means of damping is not present in the drivetrain. In this paper, a dynamic simulation model of a Type 1, direct grid-connected, fixed-speed (FS) slip-synchronous wind turbine system (SS-WTS) is developed to investigate its dynamic stability in response to the additional mechanical loads imparted onto it during transient events on the grid. The SS-WTS is not equipped with a power converter and, consequently, an understanding of its dynamic stability is critical to evaluate its ability to assist with grid services and maintain stability during transient grid conditions such as low-voltage ride-through (LVRT) events. An analytical transfer function model of a 1.5 MW geared direct grid-connected SS-WTS was derived and implemented in MATLAB/Simulink. It was found that the SS technology provides significant damping to the WTS drivetrain while maintaining dynamic stability during a severe LVRT event. Moreover, it was found that the degree of damping is directly proportional to the value of rated slip, and that high-speed drivetrains provide a greater degree of damping for a given value of rated slip. Furthermore, it is shown that the SS-WTS has the ability to assist with grid services such as primary frequency response, short-circuit strength, and reactive power compensation.

Operation of Voltage Reactive Power Control Devices based on Cooperation between Two-Voltage Class Transmission Network with PV Systems to Reduce Power Loss

2020 ◽  
Vol 140 (6) ◽  
pp. 484-494
Author(s):  
Akihisa Kaneko ◽  
Shinya Yoshizawa ◽  
Yasuhiro Hayashi ◽  
Shuhei Sugimura ◽  
Yoshinobu Ueda ◽  
...  
Keyword(s):  
Power Control ◽  
Power Loss ◽  
Reactive Power ◽  
Transmission Network ◽  
Reactive Power Control ◽  
Pv Systems ◽  
Control Devices

Prospective Transient Recovery Voltage Measurement of Short Circuit Testing Circuit by Reverse Current Injection

2019 ◽  
Vol 139 (8) ◽  
pp. 522-526
Author(s):  
Kyoya Nonaka ◽  
Tadashi Koshizuka ◽  
Eiichi Haginomori ◽  
Hisatoshi Ikeda ◽  
Takeshi Shinkai ◽  
...  
Keyword(s):  
Short Circuit ◽  
Reverse Current ◽  
Current Injection ◽  
Voltage Measurement ◽  
Circuit Testing ◽  
Transient Recovery Voltage ◽  
Recovery Voltage

scholarly journals Optimization-Based Formulations for Short-Circuit Studies with Inverter-Interfaced Generation in PowerModelsProtection.jl

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2160
Author(s):  
Arthur K. Barnes ◽  
Jose E. Tabarez ◽  
Adam Mate ◽  
Russell W. Bent
Keyword(s):  
Optimization Problem ◽  
Short Circuit ◽  
Problem Formulation ◽  
Power Delivery ◽  
Fault Current ◽  
Protective Device ◽  
Protective Relaying ◽  
Overcurrent Protection ◽  
Short Circuits ◽  
Optimization Problem Formulation

Protecting inverter-interfaced microgrids is challenging as conventional time-overcurrent protection becomes unusable due to the lack of fault current. There is a great need for novel protective relaying methods that enable the application of protection coordination on microgrids, thereby allowing for microgrids with larger areas and numbers of loads while not compromising reliable power delivery. Tools for modeling and analyzing such microgrids under fault conditions are necessary in order to help design such protective relaying and operate microgrids in a configuration that can be protected, though there is currently a lack of tools applicable to inverter-interfaced microgrids. This paper introduces the concept of applying an optimization problem formulation to the topic of inverter-interfaced microgrid fault modeling, and discusses how it can be employed both for simulating short-circuits and as a set of constraints for optimal microgrid operation to ensure protective device coordination.

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