Research on Low Voltage Ride through of Coal-Fired Power Unit Auxiliary in Henan

2013 ◽  
Vol 441 ◽  
pp. 281-285
Author(s):  
Kun Gao ◽  
Zhe Nan Zhang ◽  
Quan Sheng Zhu ◽  
Liang Yuan
Keyword(s):  
Power System ◽  
Electric Power ◽  
Power Unit ◽  
Single Phase ◽  
Low Voltage ◽  
Short Circuit ◽  
Frequency Converter ◽  
Operation Mode ◽  
Low Voltage Ride Through ◽  
Short Circuit Fault

The electric power short circuit breakdown may cause low voltage blocking of frequency-converter giving rise to power unit shutdown accident,three typical coal-fired power units are selected to emulate calculations on low voltage ride ability with considering threephase short-circuit earthing fault, threephase short-circuit earthing fault by impedance, single-phase short-circuit earthing fault ,indicating that the short-circuit fault of the lines integrating into power system would result in the voltage of house-service busbar dropping off to 25%-85%,especially threephase short-circuit earthing fault in small operation mode attacks on power unit auxiliary at the most, therefore auxiliary demands complete and dependable low voltage ride through ability. and puts forward to some reform suggestes.

scholarly journals Research on Safety Technology for High-Speed Interruption for Mining Flameproof Movable Substation

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 934
Author(s):  
Yanwen Wang ◽  
Le Wang ◽  
Sven G. Bilén ◽  
Yan Gao
Keyword(s):  
Solid State ◽  
High Speed ◽  
Single Phase ◽  
Low Voltage ◽  
Short Circuit ◽  
Rate Of Change ◽  
Simulation Experiments ◽  
Gas Detonation ◽  
Ultra High Speed ◽  
Short Circuit Fault

Due to the working condition of low-voltage cabling from the mining flameproof movable substation to the loads of the mining face being poor, it is easy to cause various external mechanical damages to the cable sheaths. Furthermore, a single-phase earth leakage fault or short-circuit fault can occur when the low-voltage cable sheaths are damaged, and electric sparks caused by these faults can lead to a gas explosion. As the gas detonation time caused by the above faults is usually more than 5 ms, the high-speed interruption solid-state switch which controls the cables must cut off the current within 3 ms. This requires the action time of the solid-state switch to be less than 1 ms, and at the same time, the sampling and calculation time of the relay protection must be less than 2 ms. Based on these problems, this paper proposes the use of a high-speed solid-state circuit breaker (SSCB) topology at the neutral point of transformer, and analyzes the conduction mechanism and shut-off mechanism of the current of the SSCB. It presents an ultra-high-speed algorithm based on pattern recognition of single-phase earth leakage fault protection, and an ultra-high-speed algorithm of short-circuit fault which is based on the rate-of-change of the current. Finally, through computer simulation experiments and semi-physical simulation experiments, the feasibility of the above three technologies is verified to ensure that when a single-phase earth leakage fault or short-circuit fault occurs in the low-voltage cable, the solid-state switch which is installed in the mining flameproof movable substation will cut off the current within 3 ms.

scholarly journals Low-Voltage Ride-Through of the Novel Voltage Source-Controlled PMSG-Based Wind Turbine Based on Switching the Virtual Resistor

2021 ◽  
Vol 11 (13) ◽  
pp. 6204
Author(s):  
Shun Sang ◽  
Binhui Pei ◽  
Jiejie Huang ◽  
Lei Zhang ◽  
Xiaocen Xue
Keyword(s):  
Energy Storage ◽  
Wind Turbine ◽  
Control Strategy ◽  
Low Voltage ◽  
Short Circuit ◽  
Voltage Source ◽  
Stable Operation ◽  
Storage Battery ◽  
Low Voltage Ride Through ◽  
Short Circuit Fault

Voltage source (VS) control based on inertia synchronization is a novel phase lock loop (PLL)-less autonomous grid-synchronization control strategy suitable for the permanent magnet synchronous generator (PMSG)-based wind turbine. It can autonomously sense grid frequency fluctuations by adopting the dynamics of DC-link capacitor, and it has the advantage of stable operation in an extremely weak grid. This paper further studies the low-voltage ride-through (LVRT) of the PMSG-based wind turbine under the VS control, and presents a wind turbine structure with the additional energy storage battery on the DC side, which not only improves its LVRT capability but also enables the wind turbine to participate in the grid primary frequency regulation. The transient characteristics of VS-controlled wind turbines after the occurrence of the short-circuit fault are analyzed, and a current suppression strategy via switching the virtual resistor in the control loop of the grid-side converter (GCS) is presented. Through coordination with the energy storage battery, the LVRT of the PMSG-based wind turbine is realized, which has the advantage of withstanding a long-time short-circuit fault. Finally, based on the PSCAD/EMTDC simulation platform, the feasibility of the control strategy and the correctness of the theoretical analysis are verified.

scholarly journals A Novel Methodology for Adaptive Coordination of Multiple Controllers in Electrical Grids

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1474
Author(s):  
Ruben Tapia-Olvera ◽  
Francisco Beltran-Carbajal ◽  
Antonio Valderrabano-Gonzalez ◽  
Omar Aguilar-Mejia
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Large Scale ◽  
Short Circuit ◽  
Dynamic Performance ◽  
Low Frequency ◽  
Electric Power System ◽  
Design Stage ◽  
Positive Interaction

This proposal is aimed to overcome the problem that arises when diverse regulation devices and controlling strategies are involved in electric power systems regulation design. When new devices are included in electric power system after the topology and regulation goals were defined, a new design stage is generally needed to obtain the desired outputs. Moreover, if the initial design is based on a linearized model around an equilibrium point, the new conditions might degrade the whole performance of the system. Our proposal demonstrates that the power system performance can be guaranteed with one design stage when an adequate adaptive scheme is updating some critic controllers’ gains. For large-scale power systems, this feature is illustrated with the use of time domain simulations, showing the dynamic behavior of the significant variables. The transient response is enhanced in terms of maximum overshoot and settling time. This is demonstrated using the deviation between the behavior of some important variables with StatCom, but without or with PSS. A B-Spline neural networks algorithm is used to define the best controllers’ gains to efficiently attenuate low frequency oscillations when a short circuit event is presented. This strategy avoids the parameters and power system model dependency; only a dataset of typical variable measurements is required to achieve the expected behavior. The inclusion of PSS and StatCom with positive interaction, enhances the dynamic performance of the system while illustrating the ability of the strategy in adding different controllers in only one design stage.

scholarly journals Fuzzy Logic Control for Low-Voltage Ride-Through Single-Phase Grid-Connected PV Inverter

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4796 ◽  
Author(s):  
Eyad Radwan ◽  
Mutasim Nour ◽  
Emad Awada ◽  
Ali Baniyounes
Keyword(s):  
Fuzzy Logic ◽  
Output Power ◽  
Single Phase ◽  
Reactive Power ◽  
Low Voltage ◽  
Operating Conditions ◽  
Pv System ◽  
Utilization Factor ◽  
Low Voltage Ride Through ◽  
Active And Reactive Power

This paper presents a control scheme for a photovoltaic (PV) system that uses a single-phase grid-connected inverter with low-voltage ride-through (LVRT) capability. In this scheme, two PI regulators are used to adjust the power angle and voltage modulation index of the inverter; therefore, controlling the inverter’s active and reactive output power, respectively. A fuzzy logic controller (FLC) is also implemented to manage the inverter’s operation during the LVRT operation. The FLC adjusts (or de-rates) the inverter’s reference active and reactive power commands based on the grid voltage sag and the power available from the PV system. Therefore, the inverter operation has been divided into two modes: (i) Maximum power point tracking (MPPT) during the normal operating conditions of the grid, and (ii) LVRT support when the grid is operating under faulty conditions. In the LVRT mode, the de-rating of the inverter active output power allows for injection of some reactive power, hence providing voltage support to the grid and enhancing the utilization factor of the inverter’s capacity. The proposed system was modelled and simulated using MATLAB Simulink. The simulation results showed good system performance in response to changes in reference power command, and in adjusting the amount of active and reactive power injected into the grid.

Short-Circuit Fault Protection of a Low Voltage DC Distribution System using Superimposed Current Components

2017 ◽  
Vol 31 (10) ◽  
pp. 86-94
Author(s):  
Saeed Zaman Jamali ◽  
Muhammad Omer Khan ◽  
Syed Basit Ali Bukhari ◽  
Muhammad Mehdi ◽  
Gi-Hyeon Gwon ◽  
...  
Keyword(s):  
Distribution System ◽  
Low Voltage ◽  
Short Circuit ◽  
Fault Protection ◽  
Dc Distribution ◽  
Short Circuit Fault
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