A cascaded high frequency AC link system with reduced switch count and low-voltage ride-through capability for large-scale PV systems

2017 ◽  
Author(s):  
Nour Elsayad ◽  
Osama A. Mohammed
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Low Voltage ◽  
Pv Systems ◽  
Low Voltage Ride Through ◽  
High Frequency Ac

scholarly journals Influence of Parasitic Parameters on DC–DC Converters and Their Method of Suppression in High Frequency Link 35 kV PV Systems

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3743
Author(s):  
Rui Li ◽  
Fangyuan Shi ◽  
Xu Cai ◽  
Haibo Xu
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Pv System ◽  
Zero Voltage Switching ◽  
Pv Systems ◽  
Magnetic Inductance ◽  
Parasitic Parameters ◽  
Saturable Inductor ◽  
Secondary Side ◽  
Pv Power Generation

Photovoltaic (PV) power generation has shown a trend towards large-scale medium- or high-voltage integration in recent years. The development of high-frequency link PV systems is necessary for the further improvement of system efficiency and the reduction of system cost. In the system, high-frequency high-step-up ratio LLC converters are one of the most important parts. However, the parasitic parameters of devices lead to a loss of zero-voltage switching (ZVS) in the LLC converter, greatly reducing the efficiency of the system, especially in such a high-frequency application. In this paper, a high-frequency link 35 kV PV system is presented. To suppress the influences of parasitic parameters in the LLC converter in the 35 kV PV system, the influence of parasitic parameters on ZVS is analyzed and expounded. Then, a suppression method is proposed to promote the realization of ZVS. This method adds a saturable inductor on the secondary side to achieve ZVS. The saturable inductor can effectively prevent the parasitic elements of the secondary side from participating in the resonance of the primary side. The experimental results show that this method achieves a higher efficiency than the traditional method by reducing the magnetic inductance.

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.

scholarly journals Fault Ride-Through Capability Enhancement for Microinverter Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Sajad Arab Ansari ◽  
Amir Reza Mizani ◽  
Siamak Ashouri ◽  
Javad Shokrollahi Moghani
Keyword(s):  
Power Systems ◽  
Single Phase ◽  
Low Voltage ◽  
Pv Systems ◽  
Low Voltage Ride Through ◽  
Fault Ride Through ◽  
Three Phase ◽  
Future Challenges ◽  
Wind Power Systems ◽  
Conduction Mode

Due to the fast growth of single-phase grid-connected photovoltaic (PV) systems, the existing grid codes are expected to be modified to guarantee the availability, quality, and reliability of the electrical system. Therefore, the future single-phase PV systems should become smarter and support low voltage ride-through (LVRT) capability, which are required for three-phase wind power systems. In this paper, the operation principle of a flyback inverter in a low-voltage ride-through operation is demonstrated in order to map future challenges. The steady state performance of the flyback inverter under voltage rise and drop conditions at boundary conduction mode (BCM) and discontinues conduction mode (DCM) is studied theoretically. The simulation results of the flyback inverter for various grid faults are presented to verify the theoretical analyses. The results indicate the fact that the flyback inverter at BCM condition can provide LVRT capability for photovoltaic microinverter applications in distributed generation (DG) systems, even though it does not need any auxiliary control branches and any limitations in components design.

scholarly journals Low-Voltage Ride-Through Capability of a Single-Stage Single-Phase Photovoltaic System Connected to the Low-Voltage Grid

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Yongheng Yang ◽  
Frede Blaabjerg
Keyword(s):  
Distribution System ◽  
Single Phase ◽  
Control Method ◽  
Low Voltage ◽  
Photovoltaic System ◽  
Pv System ◽  
Pv Systems ◽  
Low Voltage Ride Through ◽  
Three Phase ◽  
Future Challenges

The progressive growing of single-phase photovoltaic (PV) systems makes the Distribution System Operators (DSOs) update or revise the existing grid codes in order to guarantee the availability, quality, and reliability of the electrical system. It is expected that the future PV systems connected to the low-voltage grid will be more active with functionalities of low-voltage ride-through (LVRT) and the grid support capability, which is not the case today. In this paper, the operation principle is demonstrated for a single-phase grid-connected PV system in a low-voltage ride-through operation in order to map future challenges. The system is verified by simulations and experiments. Test results show that the proposed power control method is effective and the single-phase PV inverters connected to low-voltage networks are ready to provide grid support and ride-through voltage fault capability with a satisfactory performance based on the grid requirements for three-phase renewable energy systems.

Simulation Research on Improving Low Voltage Ride through of a Wind Farm by SVC

2013 ◽  
Vol 339 ◽  
pp. 608-613 ◽  
Author(s):  
Yan Shi ◽  
Chun Xu Zhang ◽  
Guang Lei Li ◽  
Yan Cheng ◽  
Shu Min Sun
Keyword(s):  
Large Scale ◽  
Wind Farm ◽  
Fault Location ◽  
Reactive Power ◽  
Low Voltage ◽  
Negative Impact ◽  
Simulation Models ◽  
Simulation Research ◽  
Low Voltage Ride Through ◽  
The Stability

Large-scale wind farm connecting to the grid will affect the stability of the grid, therefore dynamic reactive power compensation devices need to be installed at the wind farm in order to reduce the negative impact after connecting to the grid, andimprove the low voltageridethrough capability of the grid system wind turbine. Simulation models of a wind farm and SVCare built in PSCAD. In different fault location, simulations are carried out respectively to analyze the effect of SVC on LVRT. The results show that SVC can effectively improve the LVRT capability.

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