scholarly journals Presynchronous Grid-Connection Strategy of Virtual Synchronous Generator Based on Virtual Impedance

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Guanfeng Zhang ◽  
Junyou Yang ◽  
Haixin Wang ◽  
Jia Cui
Keyword(s):  
Reactive Power ◽  
Power Grid ◽  
Synchronous Generator ◽  
Synchronization Control ◽  
Distributed Power Generation ◽  
Grid Connection ◽  
Power Exchange ◽  
Phase Amplitude ◽  
Virtual Impedance ◽  
Virtual Synchronous Generator

The virtual synchronous generator (VSG) technology of inverter is widely used to provide the inertia and damping support for power system. However, an additional measurement device PLL (phase-locked loop) is required in the virtual synchronous generator grid connection to track the voltage phase, amplitude, and frequency, which restricts the flexible output of the distributed power generation system. To tackle this challenge, a method for grid-connected control of virtual synchronous generator based on virtual impedance is proposed. It is assumed that there is a virtual power exchange between the synchronous machine and the power grid when the virtual synchronous generator is off-grid, the virtual impedance is developed to calculate the virtual current, and when the virtual current is zero, the output voltage of the VSG can be synchronized with the voltage of the power grid, thereby seamlessly switching between off-grid and grid-connected VSG. A semiphysical simulation platform is built based on RT-LAB; simulation and experimental results show that the proposed grid synchronization control strategy of the VSG can achieve seamless transform between different VSG modes, which is simpler than the conventional synchronization control, while having a good active and reactive power tracing performance.

Adaptive Virtual Impedance-Based Reactive Power Sharing in Virtual Synchronous Generator Controlled Microgrids

2021 ◽  
Vol 57 (1) ◽  
pp. 46-60
Author(s):  
Xiaodong Liang ◽  
Chowdhury Andalib-Bin-Karim ◽  
Weixing Li ◽  
Massimo Mitolo ◽  
Md Nasmus Sakib Khan Shabbir
Keyword(s):  
Reactive Power ◽  
Synchronous Generator ◽  
Power Sharing ◽  
Virtual Impedance ◽  
Virtual Synchronous Generator

scholarly journals A Flexible Control Strategy for Shore-to-Ship Power System in Terms of Grid-Connected and Off-Grid Switch

2018 ◽  
Vol 25 (s2) ◽  
pp. 139-148
Author(s):  
Zhendong Ji ◽  
Zhihong Zhao ◽  
Jianhua Wang ◽  
Zhipeng Lv
Keyword(s):  
Power Supply ◽  
Control Method ◽  
Power Grid ◽  
Pollution Prevention ◽  
Synchronous Generator ◽  
Grid System ◽  
Grid Connection ◽  
Shore Power Supply ◽  
Virtual Synchronous Generator ◽  
Flexible Grid

Abstract There are promising application prospects for applying the shore power technology to the ships in the port for the purpose of pollution prevention. However, the grid-connection of the shore power supply to the ship power grid leads to current surges, damages the ship power consumption equipment, and results in the instability of the ship power grid system, which will seriously affect the reliability of the operation of the ship power grid system. In order to address this problem, the mathematical model of virtual synchronous generator is introduced in this paper. Then, a control method for the flexible grid-connection of the shore power supply to the ship power grid based on the virtual synchronous generator is proposed. Next, the output characteristics of the shore power supply are optimized to match the characteristics of the ship generator, which contributes to the flexible grid-connection of the shore power supply to the ship power grid system. The effectiveness and the feasibility of this method are verified by simulation and experiments.

scholarly journals A Novel Pre-Synchronization Control for Grid Connection of Virtual Synchronous Generator

2020 ◽  
Vol 26 (6) ◽  
pp. 25-31
Author(s):  
Xuhai Chen ◽  
Yiwang Zhang ◽  
Jiqing Dong ◽  
Xingkui Mao ◽  
Jiaqiao Chen ◽  
...  
Keyword(s):  
Phase Difference ◽  
Synchronous Generator ◽  
Phase Lock Loop ◽  
Synchronization Control ◽  
Frequency Regulation ◽  
Rotational Inertia ◽  
Large Power ◽  
Grid Connection ◽  
Tracking Time ◽  
Virtual Synchronous Generator

The virtual synchronous generator (VSG) introduces rotational inertia and damping through the droop control to take part in frequency regulation of the grid. By building the VSG model, the VSG controller, including both the frequency controller and the excitation controller, are analysed and designed. The analysis shows that the large phase difference Δθ between the VSG voltage and the grid voltage at the grid-tied moment may produce large power and damage the VSG. The proposed pre-synchronization control minimizes the phase difference, which is implemented by replacing Δθ with sinΔθ to avoid any step change from Δθ. The proposed method is able to simplify control, shorten pre-synchronization tracking time, and achieve high accuracy without a phase-lock loop. The built 12 kW VSG simulation and prototype verify the theoretical analysis, the proposed control and its associated design.

The Study of Chopper in the LVRT of Direct-Drive Wind Energy Generation System

2014 ◽  
Vol 950 ◽  
pp. 314-320 ◽  
Author(s):  
Jun Jia ◽  
Xin Xin Hu ◽  
Ping Ping Han ◽  
Yan Ping Hu
Keyword(s):  
Power System ◽  
Wind Power ◽  
Wind Turbines ◽  
Reactive Power ◽  
Power Grid ◽  
Synchronous Generator ◽  
Direct Drive ◽  
Fault Ride Through ◽  
Wind Power System ◽  
The Stability

With the scale of wind farm continuously increasing, when grid fault, the influences of the wind turbines connected to the grid on the stability of the power grid can never be ignored. Therefore, there are higher standards of the wind turbines’ abilities of fault ride-through (FRT) and producing reactive power. This paper studies the direct-drive wind power system, and the main point is the fault ride-through (FRT) of the permanent magnetic synchronous generator (PMSG) with Chopper. By establishing the dynamic model of PMSG under the environment of DigSILENT, this paper simulates the fault ride-through (FRT) of the direct-drive wind power system connecting into power grid. During the research, we focus on the stability of voltage about the Chopper to the DC bus under faults. What’s more, in this paper, we analysis the data about how the Chopper help the DC bus to improve its stability. The simulation results show that: when there is a fault on the point of common coupling, the permanent magnetic synchronous generator has the capability of fault ride-through (FRT). Especially when there is a voltage dip on the grid side, the permanent magnetic synchronous generator could produce reactive power for power grid, effectively preventing the system voltage from declining seriously, so as to improve the system stability under faults.

scholarly journals Frequency Modulation Method and System of Photovoltaic Virtual Synchronous Generator Based on Computer Technology

2021 ◽  
Vol 2143 (1) ◽  
pp. 012028
Author(s):  
Jiangfeng Zhang ◽  
Ye Su ◽  
Keke Zheng ◽  
Liyun Hua
Keyword(s):  
Power Generation ◽  
Power Grid ◽  
Synchronous Generator ◽  
Clean Energy ◽  
Voltage Regulation ◽  
Frequency Regulation ◽  
Important Research ◽  
Photovoltaic Power ◽  
Primary Frequency ◽  
Virtual Synchronous Generator

Abstract With people’s attention to environmental protection, clean energy has become an important research and development direction. Among them, photovoltaic power generation has many advantages, such as simple process, no fuel consumption, no noise, no pollution and so on. The power grid capacity is becoming larger and larger, and has a great impact on the environment. Therefore, the grid connection of photovoltaic power generation will cause major problems for the planning, operation and dispatching of power grid. Virtual synchronous generator (hereinafter referred to as VSG) technology can simulate the inertia, primary frequency regulation and voltage regulation characteristics of synchronous generator, which has become an important way to improve the dynamic frequency response ability of the system. Therefore, VSG technology has become an important research technology of photovoltaic grid connected system, among which FM method will also become an important research direction. Firstly, this paper analyzes the VSG algorithm and its basic characteristics. Finally, this paper analyzes the control scheme of overall primary frequency regulation of photovoltaic power station (hereinafter referred to as PPS).

scholarly journals Virtual Synchronous Generator Grid Connected Control Method Based on Virtual Impedance

2019 ◽  
Vol 1187 (2) ◽  
pp. 022026
Author(s):  
Bao-zhu Shao ◽  
Guan-feng Zhang ◽  
Jun-you Yang ◽  
Fei-fei Gao ◽  
Feng Sun ◽  
...  
Keyword(s):  
Control Method ◽  
Synchronous Generator ◽  
Virtual Impedance ◽  
Virtual Synchronous Generator

Distributed Virtual Synchronous Generator approach versus Singular Virtual Synchronous Generator approach: A dynamic stability evaluation

2020 ◽  
pp. 0309524X2097546
Author(s):  
Abdul Waheed Kumar ◽  
Mairaj ud din Mufti ◽  
Mubashar Yaqoob Zargar
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Reactive Power ◽  
Magnetic Energy ◽  
Dynamic Performance ◽  
Synchronous Generator ◽  
Rate Of Change ◽  
Clearing Time ◽  
Magnetic Energy Storage ◽  
Virtual Synchronous Generator

This paper reports the modeling and dynamic performance of a wind penetrated multi-area power system incorporating a Singular Virtual Synchronous Generator (SVSG)/Distributed Virtual Synchronous Generator (DVSG). The active and reactive power controls are achieved by using Superconducting Magnetic Energy Storage (SMES) as Virtual Synchronous Generator (VSG). SMES based VSG control parameters are tuned offline using genetic algorithm (GA). Two topologies of VSGs are considered in this paper: SVSG at lowest inertia generator bus (SVSGGENBUS), SVSG at load bus (SVSGLOADBUS) and DVSG of comparatively smaller rating at three lowest inertia generator buses. A modified 18 machine, 70-bus power system is simulated in MATLAB/Simulink environment. System performance is assessed for two different types of disturbances: step wind disturbance and three-phase fault. The simulation results show that rate of change of frequency (ROCOF), deviations in frequency and voltage are minimized with DVSG. Transient stability measured in terms of critical clearing time (CCT) verifies that CCT is increased by DVSG topology.

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