scholarly journals Improved Operation Strategy with Alternative Control Targets for Voltage Source Converter under Harmonically Distorted Grid Considering Inter-Harmonics

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1236 ◽  
Author(s):  
Bo Pang ◽  
Heng Nian
Keyword(s):  
Control Strategy ◽  
Control Method ◽  
Control Object ◽  
Current Control ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Pass Filter ◽  
Control Gain ◽  
Distorted Grid ◽  
The Stability

This paper proposed an improved control method for grid-connected voltage source converter (VSC), when the grid voltage consisted of the integer harmonics and inter-harmonics. Control object of the proposed control can be alternated to achieve the sinusoidal current or smooth output power, which enhances the operation adaption of VSC under the harmonically distorted grid. On the basis of a PI regulator in the fundamental current control loop, the novel control strategy was proposed with a supplementary controller which consisted of a prepositive high-pass filter and a modified proportional-derivative controller. In the proposed control, the inter-harmonics could be suppressed without detecting frequency, while the traditional resonator was effective in the premise of knowing the harmonics frequency. Also, the influence of control gain on the steady performance and the stability of VSC was analyzed, and the influences on the fundamental control caused by the proposed controller were also analyzed to verify the practicability of the proposed control strategy. Finally, the effectiveness of the proposed strategy was verified by the experiments.

scholarly journals Luenberger Position Observer Based on Deadbeat-Current Predictive Control for Sensorless PMSM

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1325 ◽  
Author(s):  
Yuan Zhu ◽  
Ben Tao ◽  
Mingkang Xiao ◽  
Gang Yang ◽  
Xingfu Zhang ◽  
...  
Keyword(s):  
Predictive Control ◽  
Control Strategy ◽  
High Speed ◽  
Control Method ◽  
Permanent Magnet Synchronous Motor ◽  
Current Control ◽  
Luenberger Observer ◽  
Control Step ◽  
The Stability ◽  
Discrete Mathematical Model

Two problems can cause control performance degradation on permanent magnet synchronous motor (PMSM) systems, namely, fluctuation of PMSM parameters and the time delay between current sampling and command value update. In order to reduce the influence of these problems, a new current-predictive control strategy is proposed in this article for medium- and high-speed PMSM. This strategy is based on the discrete mathematical model of PMSM. This new control strategy consists of two main steps: First, an integrator is applied to calculate current compensation value; second, the predictive current value is obtained through deadbeat-current predictive method. The stability of predictive control system is also proved in the article. With this deadbeat-current predictive control scheme, the real current can reach the desired value within one control-step. Based on this new current control method, Luenberger observer and phase-locked loop position tracker is applied in this article. Experimental results for 0.4 kW surface-mounted PMSM confirm the validity and excellent performance for parameters fluctuation of new current predictive control.

Fuzzy Control of Supercapacitor Current in Hybrid Diesel Generator/Fuel Cell Marine Power System

2015 ◽  
Vol 12 (2) ◽  
Author(s):  
Amin Hajizadeh ◽  
Amir Hossein Shahirinia ◽  
David C. Yu
Keyword(s):  
Fuel Cell ◽  
Fuzzy Control ◽  
Power System ◽  
Control Strategy ◽  
Current Control ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Diesel Generator ◽  
Storage Unit ◽  
Power Sources

This paper presents a power control strategy for a marine power system made up of a hybrid diesel generator, a fuel cell, and an energy storage unit. For this purpose, a self-tuning fuzzy control is designed to manage the power generation between power sources during different maneuverings and voltage disturbances (both balanced and unbalanced) in an AC system. As a solution, a current control strategy using a voltage source converter is presented. Simulation results show the response of the whole system under a test driving cycle and this variety of voltage disturbance conditions. They illustrate the performance, including power flow control and voltage disturbance ride-through capability, of the proposed control strategy.

scholarly journals POWER SYNCHRONIZATION CONTROL OF VSC-HVDC TRANSMISSION FOR WEAK AC SYSTEM

2013 ◽  
pp. 221-225
Author(s):  
SEENA. K. R ◽  
SINDHU.T. K
Keyword(s):  
Control Method ◽  
Short Circuit ◽  
Vector Current ◽  
Current Control ◽  
Voltage Source ◽  
Synchronization Control ◽  
Voltage Source Converter ◽  
Hvdc Transmission ◽  
Ac Systems ◽  
Weak Ac System

In this paper voltage source converter based HVDC transmission system is used for connecting two ac systems. The control method used is power synchronization control. This method is different from other control methods and it uses the internal synchronization mechanism in ac systems. It is applied for all grid connected VSC’s especially for HVDC application. This control method gives strong voltage support to a weak ac system. It shows that the proposed control allows 0.86 p.u power to be transferred from a system with short circuit ratio of 1.2 to a system with an SCR of 1.The result is compared with the vector current control for the same ac system where it can transfer only 0.4 p.u. The simulations in MATLAB/Simulink are done to demonstrate the system and observe the system behavior under three phase AC faults.

scholarly journals Control Strategy for Grid Connected Inverters Under Unbalanced Network Conditions - A DOb Based Decoupled Current Approach

2017 ◽  
Author(s):  
Emre Ozsoy ◽  
Sanjeevikumar Padmanaban ◽  
Lucian Mihet-Popa ◽  
Viliam Fedák ◽  
Fiaz Ahmad ◽  
...  
Keyword(s):  
Control Strategy ◽  
Current Approach ◽  
Current Control ◽  
Positive Sequence ◽  
Voltage Source ◽  
Renewable Sources ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Negative Sequence ◽  
Low Pass

Penetration of grid connected inverters (GCI) has arisen in power systems due to increasing integration of renewable sources. However, restrictive grid codes require that renewable sources connected to the grid with power electronic systems must be properly connected and appropriate currents must be injected to support stability of the grid under grid faults. Simultaneous injection of symmetrical positive and negative sequence currents is mandatory to support stabilization of grid at the instant of grid faults. Conventional synchronously rotating frame dq current controllers are insufficient under grid faults due to low bandwidth of PI controllers. This paper proposes a new grid current control strategy for grid connected voltage source inverters under unbalanced grid voltage conditions. A proportional current controller with a first order low pass filter disturbance observer (DOb) is proposed which establishes positive sequence power requirements and independently control negative sequence current components under unbalanced voltage conditions. The method does not need any parameter, since it estimates nonlinear terms with low pass filter DOb. Simulations are implemented in Matlab/Simulink platform demonstrating the effectiveness of proposed method.

Research on Practical Control Circuit of SVG in Single-Phase Low Voltage Field

2013 ◽  
Vol 694-697 ◽  
pp. 1469-1472
Author(s):  
Cong Mei Zha ◽  
Yan Dong
Keyword(s):  
Circuit Design ◽  
Control Strategy ◽  
Single Phase ◽  
Reactive Power ◽  
Control Method ◽  
Low Voltage ◽  
Current Control ◽  
Control Circuit ◽  
Voltage Source ◽  
Static Var Generator

For the use of Static Var Generator (SVG) in dynamic reactive power compensation of low voltage field, this paper proposes a reactive current control strategy suitable for single-phase bridge voltage source SVG and gives the main control circuit of this control method. The experimental results verify the effectiveness and practicality of this control strategy and the circuit design.

scholarly journals A Full-bridge Director Switches based Multilevel Converter with DC Fault Blocking Capability and Its Predictive Control Strategy

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 91 ◽  
Author(s):  
Jin Zhu ◽  
Tongzhen Wei ◽  
Qunhai Huo ◽  
Jingyuan Yin
Keyword(s):  
Predictive Control ◽  
Control Strategy ◽  
Control Method ◽  
Experimental Studies ◽  
Low Frequency ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Multilevel Converter ◽  
High Voltage Direct Current ◽  
Dc Fault

Voltage source converter-based high-voltage direct current transmission system (VSC-HVDC) technology has been widely used. However, traditional half-bridge sub module (HBSM)-based module multilevel converter (MMC) cannot block a DC fault current. This paper proposes that a full-bridge director switches based multi-level converter can offer features such as DC side fault blocking capability and is more compact and lower cost than other existing MMC topologies. A suitable predictive control strategy is proposed to minimize the error of the output AC current and the capacitor voltage of the sub-module while the director switches are operated in low-frequency mode. The validity of the proposed topology and control method is demonstrated based on simulation and experimental studies.

scholarly journals Operation Zone Analysis of the Voltage Source Converter Based on the Influence of Different Grid Strengths

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 153
Author(s):  
Wenning Wang ◽  
Kejun Li ◽  
Kaiqi Sun ◽  
Jianjian Wang
Keyword(s):  
Renewable Energy ◽  
Control Strategies ◽  
Short Circuit ◽  
Vector Current ◽  
Current Control ◽  
Voltage Source ◽  
Synchronization Control ◽  
Voltage Source Converter ◽  
Operating Stability ◽  
The Stability

With the increasing penetration of renewable energy into the power system, the voltage source converter (VSC) for integrating renewable energy has become the most common device in the electric network. However, the operating stability of the VSC is strongly dependent on its operating control strategy, which is also highly related to the strength of the AC system. Choosing the control strategy of VSC for different strengths of AC systems becomes an essential issue for maintaining the symmetry between high proportion of renewable energy integration and stable operation of AC system. In order to obtain the operation zones of the control strategies of the VSC under different strengths of AC system, in this paper, the two common VSC control strategies, vector current control (VCC) and power synchronization control (PSC), are compared. Firstly, the principle of VCC and PSC are introduced. Then, based on the short circuit ratio (SCR) and the power limit calculation under steady-state conditions of the VSC, the operation zones of the vector current control and power synchronization control are proposed. Finally, a medium voltage modular multilevel converter (MMC) system was built in PSCAD/EMTDC and the proposed operation zones of the VCC and PSC were tested by changing the SCR of the modified IEEE 33 bus system and analyzed via the critical short circuit ratio (CSCR) analysis, the small-signal stability analysis, and transient stability analysis. The results indicate that, as the SCR decreases, the VSC based on VCC is gradually worked into unstable conditions, while the stability of VSC based on PSC gradually increases. The analysis results provide a criterion for the converter operation strategy change that could significantly improve the operating stability of the VSC in the power system and realize the symmetry of the stability of the converter and the change of the strength of the AC system.

Inductor Saturation Compensation in Three-Phase Three-Wire Voltage-Source Converters via Inverse System Dynamics-I

2020 ◽  
Author(s):  
Ziya Özkan ◽  
Ahmet Masum Hava
Keyword(s):  
Dynamic Model ◽  
Dynamic Performance ◽  
Current Control ◽  
Inverse System ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Two Phase ◽  
Inverse Dynamic ◽  
Three Phase ◽  
Steady State Current

In three-phase three-wire (3P3W) voltage-source converter (VSC) systems, utilization of filter inductors with deep saturation characteristics is often advantageous due to the improved size, cost, and efficiency. However, with the use of conventional synchronous frame current control (CSCC) methods, the inductor saturation results in significant dynamic performance loss and poor steady-state current waveform quality. This paper proposes an inverse dynamic model based compensation (IDMBC) method to overcome these performance issues. Accordingly, a review of inductor saturation and core materials is performed, and the motivation on the use of saturable inductors is clarified. Then, two-phase exact modelling of the 3P3W VSC control system is obtained and the drawbacks of CSCC have been demonstrated analytically. Based on the exact modelling, the inverse system dynamic model of the nonlinear system is obtained and employed such that the nonlinear plant is converted to a fictitious linear inductor system for linear current regulators to perform satisfactorily.

scholarly journals A Unified Control Strategy of Distributed Generation for Grid-Connected and Islanded Operation Conditions Using an Artificial Neural Network

2021 ◽  
Vol 13 (11) ◽  
pp. 6388
Author(s):  
Karim M. El-Sharawy ◽  
Hatem Y. Diab ◽  
Mahmoud O. Abdelsalam ◽  
Mostafa I. Marei
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Control System ◽  
Distributed Generation ◽  
Control Strategy ◽  
Current Control ◽  
Operating Conditions ◽  
Pi Controllers ◽  
Artificial Neural ◽  
The Stability

This article presents a control strategy that enables both islanded and grid-tied operations of a three-phase inverter in distributed generation. This distributed generation (DG) is based on a dramatically evolved direct current (DC) source. A unified control strategy is introduced to operate the interface in either the isolated or grid-connected modes. The proposed control system is based on the instantaneous tracking of the active power flow in order to achieve current control in the grid-connected mode and retain the stability of the frequency using phase-locked loop (PLL) circuits at the point of common coupling (PCC), in addition to managing the reactive power supplied to the grid. On the other side, the proposed control system is also based on the instantaneous tracking of the voltage to achieve the voltage control in the standalone mode and retain the stability of the frequency by using another circuit including a special equation (wt = 2πft, f = 50 Hz). This utilization provides the ability to obtain voltage stability across the critical load. One benefit of the proposed control strategy is that the design of the controller remains unconverted for other operating conditions. The simulation results are added to evaluate the performance of the proposed control technology using a different method; the first method used basic proportional integration (PI) controllers, and the second method used adaptive proportional integration (PI) controllers, i.e., an Artificial Neural Network (ANN).

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