scholarly journals Dynamic Voltage Support of Converters during Grid Faults in Accordance with National Grid Code Requirements

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2484 ◽  
Author(s):  
Jürgen Marchgraber ◽  
Wolfgang Gawlik
Keyword(s):  
Simulation Model ◽  
System Stability ◽  
Current Output ◽  
Current Limitation ◽  
Fault Ride Through ◽  
Maximum Current ◽  
Dynamic Voltage ◽  
Grid Codes ◽  
Voltage Support ◽  
A Current

To ensure system stability, national grid codes often require converter-based generators to provide fault-ride-through (FRT) capabilities and dynamic voltage support, according to which they should stay connected and support the voltage during fault situations. The requirements for dynamic voltage support include the injection of reactive current in the positive- as well as negative-sequence system, directly proportional to the change of the corresponding voltage between fault and pre-fault. Since this requirement may lead to a reference current surpassing the maximum current capability, the converter control has to contain a proper current limitation. This paper presents an algorithm for such a current limitation and a simulation model of a converter and its control, which applies this algorithm. Based on voltage measurements, which were measured during forced short-circuits in the real grid, the simulation model is used to simulate the behavior of a converter in reaction to these voltage measurements. The results show that the converter control using this algorithm for current limitation guarantees a current output below the maximum current capability while respecting the requirements for dynamic voltage support of the relevant grid codes.

Improving stability of utility-tied wind generators using dynamic voltage restorer

2014 ◽  
Vol 25 (4) ◽  
pp. 71-79 ◽  
Author(s):  
G Sivasankar ◽  
V Suresh Kumar
Keyword(s):  
Wind Power ◽  
Wind Farm ◽  
Short Circuit ◽  
Wind Farms ◽  
System Stability ◽  
Dynamic Voltage Restorer ◽  
Fault Ride Through ◽  
Voltage Restorer ◽  
Dynamic Voltage ◽  
The Stability

The generation of electricity using wind power is significantly increasing and has received considerable attention in recent years. One important problem with the induction generator based wind farms is that they are vulnerable to voltage disturbances and short circuit faults. Any such disturbance may cause wind farm outages. Since wind power contribution is in considerable percentage, such outages may lead to power system stability issues and also violate the grid code requirements. Thus, improving the reliability of wind farms is essential to maintain the stability of the system. The proposed strategy is to use Dynamic Voltage Restorer (DVR), which is one of the promising devices to compensate the voltage disturbance and to improve the stability of the system. It provides the wind generator with the fault ride through capability and improves the reliability of the system. Extensive simulation results are included to illustrate the operation of DVR and fault compensation.

Two opposite effects of ATP on the apparent sensitivity of the cGMP-gated channel of the carp retinal cone

1997 ◽  
Vol 14 (4) ◽  
pp. 609-615 ◽  
Author(s):  
Shu-Ichi Watanabe ◽  
Jing Shen
Keyword(s):  
Cone Photoreceptors ◽  
Apparent Affinity ◽  
Enhancing Effect ◽  
Cyclic Monophosphate ◽  
Maximum Current ◽  
Gated Channel ◽  
Retinal Cone ◽  
A Current

AbstractEffects of ATP on the activity of cGMP-gated channels from carp cone photoreceptors were studied. In 29% of the patches examined (N = 45), ATP (1 mM) enhanced a current evoked by cGMP (20 μM, up to about 100%), in 33%, ATP suppressed it by up to about 90%, and in the remaining 38%, ATP had no effect. ATP showed similar effects on a current evoked by 8-bromoguanosine 3′,5′-cyclic monophosphate (2 μM, enhancing in 42% of the patches, suppressing in 25%, no effect in 33%, N = 12), suggesting that the effects were not through modulation of the phosphodiesterase. Both of the effects, enhancement and suppression, were produced by a change in apparent affinity for cGMP, since (1) the maximum current evoked by cGMP of the saturating concentration (≥1 mM) was not affected, and (2) the A1/2 value decreased by approximately 45% (N = 2) or increased by approximately 25% (N = 2). A lower pH (approximately 6) facilitated the enhancing effect. ATP-γ-S (1 mM) showed a suppressing effect in 80% of the patches and no effect in 20% of the patches (N = 10). However, ATP-γ-S did not show an enhancing effect. Thus, ATP had two opposite effects through different mechanisms on the apparent sensitivity of the channel to cGMP; increasing and decreasing.

Grid-Forming Control with Current Limitation for MMC under Unbalanced Fault Ride-Through

2021 ◽  
pp. 1-1
Author(s):  
Julian Freytes ◽  
Jiaqi Li ◽  
Guillaume De-Preville ◽  
Marc Thouvenin
Keyword(s):  
Current Limitation ◽  
Fault Ride Through

scholarly journals Analytical Modeling and Validation of a Preloaded Piezoceramic Current Output

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 353
Author(s):  
Bin Zhang ◽  
Hongsheng Liu ◽  
Dezhi Li ◽  
Jinhui Liang ◽  
Jun Gao
Keyword(s):  
Energy Harvesting ◽  
Integrated Circuit ◽  
Microelectromechanical Systems ◽  
Experimental Testing ◽  
Current Source ◽  
Model Parameters ◽  
Current Output ◽  
System A ◽  
A Current ◽  
Piezoelectric Characteristics

Energy harvesting using piezoceramic has drawn a lot of attention in recent years. Its potential usage in microelectromechanical systems is starting to become a reality thanks to the development of an integrated circuit. An accurate equivalent circuit of piezoceramic is important in energy harvesting and the sensing system. A piezoceramic is always considered to be a current source according to empirical testing, instead of the derivation from its piezoelectric characteristics, which lacks accuracy under complicated mechanical excitation situations. In this study, a new current output model is developed to accurately estimate its value under various kinds of stimulation. Considering the frequency, amplitude and preload variation imposed on a piezoceramic, the multivariate model parameters are obtained in relation to piezo coefficients. Using this model, the current output could be easily calculated without experimental testing in order to quickly estimate the output power in energy harvesting whatever its geometric shape and the various excitations.

Influence Assessment of UHV Project on Jiangxi Power Grid

2014 ◽  
Vol 960-961 ◽  
pp. 1029-1033
Author(s):  
Yong Chun Su ◽  
Kai Xuan Chang
Keyword(s):  
Power System ◽  
Simulation Model ◽  
Power Transmission ◽  
Power Grid ◽  
Low Frequency ◽  
System Stability ◽  
Energy Structure ◽  
Low Frequency Oscillation ◽  
Structure Transition ◽  
Speed Up

In order to face the challenge of our economy and the environment, it is needed to speed up the energy structure transition and UItra High voltage (UHV) transmission has become an inevitable choice. Researches on the influence of UHV project to Jiangxi power grid are carried out in this paper. Using advanced digital power system simulator (ADPSS), the real-time simulation model of Jiangxi power grid is build up including the UHV project. Based on the simulation model, the problem of low frequency oscillation in Jiangxi power system is studied after the UHV power transmission project accessed. The influence of the UHV transmission line faults on system stability of Jiangxi grid is also researched.

scholarly journals Current mode sigma-delta modulator designed with the help of transistor’s size optimization tool

2015 ◽  
Vol 63 (4) ◽  
pp. 919-922 ◽  
Author(s):  
P. Śniatała ◽  
M. Naumowicz ◽  
A. Handkiewicz ◽  
S. Szczęsny ◽  
J.L.A. de Melo ◽  
...  
Keyword(s):  
Current Mode ◽  
Cmos Technology ◽  
Clock Frequency ◽  
Mode Structure ◽  
Sigma Delta Modulator ◽  
Sigma Delta ◽  
Current Output ◽  
Image Pixels ◽  
Time Loop ◽  
A Current

Abstract The paper presents a second order current mode sigma-delta modulator designed with the help of a new elaborated tool to optimize the transistor sizes. The circuit is composed of two continuous time loop filters, a current comparator and a one bit DAC with a current output. The resulting circuit, designed in a 65 nm 1.2 V CMOS technology, has a bandwidth of 2 MHz for a clock frequency of 250 MHz. The electrical simulation results show that it achieves a maximum signal-to-noise-plus-distortion ratio (SNDR) of 53.6 dB while dissipating 93 μW, which corresponds to an efficiency of 59.7 fJ/conv. The fully current mode structure makes the circuit suitable to be applied in a current mode signal processing like biosensors or image pixels arrays.

scholarly journals Improved Fault Ride Through Capability in DFIG Based Wind Turbines Using Dynamic Voltage Restorer With Combined Feed-Forward and Feed-Back Control

IEEE Access ◽  
2017 ◽  
Vol 5 ◽  
pp. 20494-20503 ◽  
Author(s):  
Rini Ann Jerin Amalorpavaraj ◽  
Palanisamy Kaliannan ◽  
Sanjeevikumar Padmanaban ◽  
Umashankar Subramaniam ◽  
Vigna K. Ramachandaramurthy
Keyword(s):  
Wind Turbines ◽  
Dynamic Voltage Restorer ◽  
Feed Forward ◽  
Fault Ride Through ◽  
Voltage Restorer ◽  
Dynamic Voltage ◽  
Combined Feed
Sign in / Sign up

Export Citation Format

Share Document