scholarly journals Modeling and Parameter Optimization of Grid-Connected Photovoltaic Systems Considering the Low Voltage Ride-through Control

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3972
Author(s):  
Li Wang ◽  
Teng Qiao ◽  
Bin Zhao ◽  
Xiangjun Zeng ◽  
Qing Yuan
Keyword(s):  
Parameter Optimization ◽  
Low Voltage ◽  
Power Grid ◽  
Current Loop ◽  
Stable Operation ◽  
Power Fluctuation ◽  
Grid Current ◽  
Low Voltage Ride Through ◽  
Dc Bus ◽  
Bus Voltage

The asymmetric faults often cause the power grid current imbalance and power grid oscillation, which brings great instability risk to the power grid. To address this problem, this paper presented a modeling and parameter optimization method of grid-connected photovoltaic (PV) systems, considering the low voltage ride-through (LVRT) control. The harmonics of the grid current under asymmetric faults were analyzed based on the negative-sequence voltage feedforward control method. The notch filter was added to the voltage loop to filter out the harmonic components of the DC bus voltage and reduce the harmonic contents of the given grid current value. The proportional resonant (PR) controller was added to the current loop. The combination of these two components could reduce the 3rd, 5th, and 7th harmonics of the grid current and the output power fluctuation. Then, the parameters of the inverter controller were identified by the adaptive differential evolution (ADE) algorithm based on the sensitivity analysis. The effectiveness of the proposed method was compared with two other strategies under the asymmetric grid faults. The suppression of DC bus voltage fluctuation, power fluctuation, and low-order harmonics of the grid current all had better results, ensuring the safe and stable operation of the PV plant under grid faults.

scholarly journals Control Strategy of Three-Phase Photovoltaic Inverter under Low-Voltage Ride-Through Condition

2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
Xianbo Wang ◽  
Zhixin Yang ◽  
Bo Fan ◽  
Wei Xu
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Drop ◽  
Stable Operation ◽  
Power Fluctuation ◽  
Negative Sequence ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Grid Side

The new energy promoting community has recently witnessed a surge of developments in photovoltaic power generation technologies. To fulfill the grid code requirement of photovoltaic inverter under low-voltage ride-through (LVRT) condition, by utilizing the asymmetry feature of grid voltage, this paper aims to control both restraining negative sequence current and reactive power fluctuation on grid side to maintain balanced output of inverter. Two mathematical inverter models of grid-connected inverter containing LCL grid-side filter under both symmetrical and asymmetric grid are proposed. PR controller method is put forward based on inverter model under asymmetric grid. To ensure the stable operation of the inverter, grid voltage feedforward method is introduced to restrain current shock at the moment of voltage drop. Stable grid-connected operation and LVRT ability at grid drop have been achieved via a combination of rapid positive and negative sequence component extraction of accurate grid voltage synchronizing signals. Simulation and experimental results have verified the superior effectiveness of our proposed control strategy.

A Control Strategy for DFIM to Minimize DC Bus Voltage Fluctuations and Torque Oscillations

2017 ◽  
Vol 5 (2) ◽  
pp. 277
Author(s):  
G. Venu Madhav ◽  
Y. P. Obulesu
Keyword(s):  
Stable Operation ◽  
Doubly Fed Induction Generator ◽  
Position Sensor ◽  
Integral Control ◽  
Rotor Resistance ◽  
Sequence Components ◽  
Dc Bus ◽  
Bus Voltage ◽  
Proportional Integral Control ◽  
Doubly Fed

The Direct Power Contro; has many advantages like it avoids the usage of integration of PWM voltages which leads to stable operation even at zero rotor frequency, it is position sensor less and hence will not depend on machine parameters like stator or rotor resistance. In case of network unbalance, if the system is operated with constant active and reactive powers, it leads to oscillations in the electromagnetic torque and currents exchange with the grid will become non- sinusoidal, which is not good for the system as it increases the mechanical stress. In this paper, both the rotor connected converter and grid connected converter are fed with DPC strategy along with that a Torque Oscillations Cancellation scheme is applied to RSC and Proportional Integral control based power references generation strategy without calculating the sequence components and with elimination of DC bus voltage oscillations is applied to stator-side converter in order to achieve non-oscillating torque accompanied by quality improved current exchange with the grid. The simulation results of Doubly Fed Induction Generator with and without fault clearly shows that the performance of the proposed scheme is validated.

Research on Optimal Application of SVG in Substation Regulated Voltage

2014 ◽  
Vol 602-605 ◽  
pp. 2970-2973
Author(s):  
Ying Nan Wang ◽  
Feng Li Han ◽  
Zhe Ren ◽  
Peng Jin ◽  
Hai Sheng Li ◽  
...  
Keyword(s):  
Low Voltage ◽  
Voltage Drop ◽  
Power Grid ◽  
Voltage Stabilization ◽  
Entire Line ◽  
Bus Voltage

In order to solve the problem of low voltage at a terminal rural power grid 66kV substation, a 5000-kilovar SVG is arranged in the substation to elevate and stabilize the 10kV bus voltage. Since put into operation, SVG runs well, solving the problem of low voltage while lowering the loss of the entire line. However, in some cases, people find that while stabilizing the bus voltage, SVG causes voltage drop in adjacent substation, and act of the intelligent capacitor unit in the adjacent substation, thus leading to opposite reactive response of SVG, affecting voltage stabilization of the two substations and adding up to equipment loss. This paper analyzes this phenomenon and has proposed an approach of correction.

Comparative Study on Low Voltage Ride-Through Test Methods for Grid-Connected Photovoltaic Inverter

2014 ◽  
Vol 590 ◽  
pp. 495-499
Author(s):  
Wen Jin Wu ◽  
Jian Hui Su ◽  
Hai Ning Wang
Keyword(s):  
Large Scale ◽  
Low Voltage ◽  
Voltage Drop ◽  
Power Grid ◽  
Design For Test ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Technical Requirements ◽  
Test Platform ◽  
The Stability

The large scale photovoltaic plants have more effects on the stability of regional power grid with the rapid increase of photovoltaic generation ratio in some areas. According to the grid guideline, the photovoltaic inverter is required to maintain the running status even the grid voltage drops and needs to have the capability to contribute towards the stability of power grid voltage and to support the grid voltage ride through. To test the ability of photovoltaic inverter low voltage ride through (LVRT), the test platform to simulate all kinds of fault for voltage drop needs to be set up. By the low voltage through technical requirements, this paper puts forward three kinds of design for test platform and analyzes respective work principle and characteristics, in order to provide optimization solution for the low voltage ride through test work.

Control Strategy of Low Voltage Ride-Through for Grid-Connected Photovoltaic Power System Based on Predictive Current

2014 ◽  
Vol 556-562 ◽  
pp. 1753-1756
Author(s):  
Ming Guang Zhang ◽  
Xiao Jing Chen
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Photovoltaic System ◽  
Stable Operation ◽  
Voltage Sags ◽  
Low Voltage Ride Through ◽  
Pv Inverter ◽  
Current Instruction ◽  
Voltage Recovery

The control strategy based on predictive current is proposed to solve problems that destruct stable operation of grid-connected photovoltaic system during asymmetrical fall. A mathematical model of PV inverter is established to calculate current instruction; a method of tracking based on predictive current is proposed to reduce the fluctuations of 2 times frequency. In the meantime, PV inverter provides reactive power to support voltage recovery according to the depth of grid voltage sags and realize LVRT. The result also shows that the proposed control strategy can reduce wave of DC voltage and provide reactive power to support voltage recovery.

scholarly journals Multi level Transformer less PV Inverter with Reduced Switching Losses and Elimination of CM leakage Current

2020 ◽  
Vol 9 (11) ◽  
pp. 223-228
Keyword(s):  
Leakage Current ◽  
Low Voltage ◽  
Stable Operation ◽  
Efficient Operation ◽  
Low Voltage Ride Through ◽  
Point Tracking ◽  
Pv Inverter ◽  
Switching Losses ◽  
Power Point Tracking ◽  
Power Point

In order to have efficient operation of grid connected Photovoltaic (PV) inverter, the issue of leakage current must be completely eliminated. For this new transformerless multilevel inverter is proposed in this paper with (k-1) levels in which k denotes the number of switches. The inverter provides zero common mode leakage current and also capable of operating under half of rated PV voltage, hence make this proposed inverter topology as LVRT (low voltage ride through) capable. Different modes are employed for the stable operation of the proposed inverter with varying input PV voltage. Simulation work is carried out for three, five and seven level proposed inverter topologies in MATLAB/Simulink software which determines its maximum power point tracking performance. Here the THD (Total Harmonic Distortions) of 3, 5 and 7 levels are compared.

scholarly journals Adaptive Control of Fuel Cell Converter Based on a New Hamiltonian Energy Function for Stabilizing the DC Bus in DC Microgrid Applications

Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 2035 ◽  
Author(s):  
Phatiphat Thounthong ◽  
Pongsiri Mungporn ◽  
Serge Pierfederici ◽  
Damien Guilbert ◽  
Nicu Bizon
Keyword(s):  
Fuel Cell ◽  
Energy Function ◽  
Low Voltage ◽  
Hydrogen Gas ◽  
Hydrogen Fuel Cell ◽  
Dc Microgrid ◽  
Power Load ◽  
Dc Bus ◽  
Bus Voltage ◽  
Multi Phase

DC microgrid applications include electric vehicle systems, shipboard power systems, and More Electric Aircraft (MEA), which produce power at a low voltage level. Rapid developments in hydrogen fuel cell (FC) energy have extended the applications of multi-phase parallel interleaved step-up converters in stabilizing DC bus voltage. The cascade architecture of power converters in DC microgrids may lead to large oscillation and even risks of instability given that the load converters considered as loads feature constant power load (CPL) characteristics. In this article, the output DC bus voltage stabilization and the current sharing of a multi-phase parallel interleaved FC boost converter is presented. The extended Port-Hamiltonian (pH) form has been proposed with the robust controller by adding an integrator action based on the Lyapunov−Energy function, named “Adaptive Hamiltonian PI controller”. The stability and robustness of the designed controller have been estimated by using Mathematica and Matlab/Simulink environments and successfully authenticated by performing experimental results in the laboratory. The results have been obtained using a 2.5 kW prototype FC converter (by two-phase parallel interleaved boost converters) with a dSPACE MicroLabBox platform. The FC main source system is based on a fuel reformer engine that transforms fuel methanol and water into hydrogen gas H2 to a polymer electrolyte membrane FC stack (50 V, 2.5 kW).

Low Voltage Ride through (LVRT) Control of Double-Fed Wind-Driven Generator

2012 ◽  
Vol 499 ◽  
pp. 400-404
Author(s):  
Jian Hong Zheng ◽  
Jie Feng Li ◽  
Yu Zhi Gao
Keyword(s):  
Power System ◽  
Wind Turbine ◽  
Wind Power ◽  
Control Method ◽  
Low Voltage ◽  
Voltage Drop ◽  
Power Grid ◽  
Rapid Development ◽  
Low Voltage Ride Through ◽  
The Impact

With the rapid development of the wind power, it is no longer an isolated power system and gradually incorporated in the local power grid. However, as the increasing proportion of the installed wind power capacity in the power grid, the affection of the wind turbine to the region power system is getting heavier, which inevitably bring some new problems to the power system. The low voltage ride through (LVRT) is the direct embodiment of the power quality. In this paper, we fist analyze the impact of the voltage drop on the double-fed wind turbine. Then, a LVRT control method is proposed based on hardware realization. The detailed explanation of the proposed control method is given at last.

DC-Bus Voltage Control Strategy Based on Low-Pass Filter for Three-Phase Four-Wire APF

2013 ◽  
Vol 732-733 ◽  
pp. 1167-1170
Author(s):  
Xia Feng ◽  
Xiao Jian Zhong ◽  
Qun Wei Xu ◽  
Guo Zhu Chen
Keyword(s):  
Voltage Control ◽  
Stable Operation ◽  
Voltage Control Strategy ◽  
Signal Model ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Three Phase ◽  
Low Pass ◽  
Dc Bus ◽  
Bus Voltage

The DC-bus voltage control is critical for stable operation of the three-phase four-wire Active Power Filter. DC-bus stable voltage loop and balance voltage loop are established based on the small signal model. Considering the disadvantages of the traditional PI control, second-order low-pass filter is introduced into the proposed controller. Simulation and experimental results are conducted to validate the effectiveness of the proposed strategy.

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