A Unified Control Structure for Grid Connected and Islanded Mode of Operation of Voltage Source Converter Based Distributed Generation Units Under Unbalanced and Non-Linear Conditions

2020 ◽  
Vol 35 (4) ◽  
pp. 1758-1768 ◽  
Author(s):  
Noel Richard Merritt ◽  
Chandan Chakraborty ◽  
Prabodh Bajpai ◽  
Bikash C. Pal
Author(s):  
Akram Qashou ◽  
Sufian Yousef ◽  
Abdallah A. Smadi ◽  
Amani A. AlOmari

AbstractThe purpose of this paper is to describe the design of a Hybrid Series Active Power Filter (HSeAPF) system to improve the quality of power on three-phase power distribution grids. The system controls are comprise of Pulse Width Modulation (PWM) based on the Synchronous Reference Frame (SRF) theory, and supported by Phase Locked Loop (PLL) for generating the switching pulses to control a Voltage Source Converter (VSC). The DC link voltage is controlled by Non-Linear Sliding Mode Control (SMC) for faster response and to ensure that it is maintained at a constant value. When this voltage is compared with Proportional Integral (PI), then the improvements made can be shown. The function of HSeAPF control is to eliminate voltage fluctuations, voltage swell/sag, and prevent voltage/current harmonics are produced by both non-linear loads and small inverters connected to the distribution network. A digital Phase Locked Loop that generates frequencies and an oscillating phase-locked output signal controls the voltage. The results from the simulation indicate that the HSeAPF can effectively suppress the dynamic and harmonic reactive power compensation system. Also, the distribution network has a low Total Harmonic Distortion (< 5%), demonstrating that the designed system is efficient, which is an essential requirement when it comes to the IEEE-519 and IEC 61,000–3-6 standards.


Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1363
Author(s):  
Harith R. Wickramasinghe ◽  
Pingyang Sun ◽  
Georgios Konstantinou

This paper demonstrates the interoperability of an emerging alternate arm converter (AAC) with the state-of-the-art modular multilevel converter (MMC) in high-voltage direct current (HVDC) systems based on a hybrid VSC-HVDC system. The paper also showcases the parameter derivation of the hybrid HVDC system and its detailed control structure. The study provides preliminary steps towards detailed analysis of AAC interoperability in complex hybrid dc grid configurations. A detailed set of results based on the 800 MVA hybrid voltage source converter (VSC)-HVDC system showcases the interoperability performance of the AAC under different operating scenarios and verifies its associated control functions.


Author(s):  
Ameerul A. J. Jeman ◽  
Naeem M. S. Hannoon ◽  
Nabil Hidayat ◽  
Mohamed.M.H. Adam ◽  
Ismail Musirin ◽  
...  

<span>Voltage-source converter (VSC) topology is widely used for grid interfacing of distributed generation (DG) systems such as the photovoltaic system (PV). Since the operation of the VSC is essential to ensure quality of active and reactive power injected to the grid, a control approach is needed to deal with the uncertainties in the grid such as faults. This paper presents a non-linear controller design for a three-phase voltage source converter (VSC). The dynamic variables adopted for the VSC are the instantaneous real and reactive power components. The control approach that interface the VSC between the PV system and the grid are subjected to the current-voltage based. PV system injects active power to the grid and local load while utility grid monitors the power compensation of load reactive power. The proposed non-linear control strategy is implemented for the VSC to ensure fast error tracking and finite convergence time. The adaptive nature of the proposed non-linear control provides more robustness, less sluggish fault recovery compared to conventional PI control. The comprehensive numerical model is demonstrated in MATLAB script environment with power system disturbances such as faults in the grid. The simulation of proposed system is being carried out in MATLAB/SIMULINK environment to validate the control scheme. The proposed control system regulates the VSC ac side real and reactive power component and the dc side voltage.</span>


2018 ◽  
Vol 7 (2.8) ◽  
pp. 673
Author(s):  
Savitha Venkatesan ◽  
Booma Nagarajan

Due to unpredicted non-linear loads, power quality problems, a raise in the transmission system. One such problem is voltage sag. Voltage sag is caused by the non-linear load which demands reactive power, but the balanced 3F source provides required reactive power of the load with reduced voltage at the receiving end. In this paper, simulation study has been performed to reducethe voltage sag issue. A transmission system with generation source with different loading conditions is considered and study has been done. A 3F medium P model transmission line is designed with a power source of 11kV.  A shunt connected compensation unit called Static Synchronous Compensator (STATCOM) reduces the voltage sag in the transmission line. STATCOM provides the required reactive power demanded by the non-linear load along with the source for compensation of voltage sag. The STATCOM circuit comprises of Voltage source converter(VSC) unit and a DC source. Reactive power compensation is done by VSC unit firing angle control. The source of the STATCOM can also be from renewable energy system. This AC source is converted by a AC-DC-AC converter unit.The firing angle is controlled by the control unit which ensures the continuous and balanced power flow even under sudden change in load conditions. The simulation results depict the characteristics of the developed STATCOM.


2009 ◽  
Vol 57 (4) ◽  
pp. 337-343 ◽  
Author(s):  
M. Bobrowska-Rafał ◽  
K. Rafał ◽  
G. Abad ◽  
M. Jasiński

Control of PWM rectifier under grid voltage dipsThis paper investigates control structure for grid connected three-phase two-level Voltage Source Converter (VSC) under distorted grid voltage conditions. Grid voltage is distorted by balanced and unbalanced voltage dips and higher harmonics. To address the problem, the control structure of converter is presented. The control system is a modification of Voltage Oriented Control (VOC) based on Dual Vector Current Controllers (DVCC). Grid synchronization under distorted voltage is achieved by employing Phase Locked Loop (PLL). Simulation and experimental results, which illustrate properties of proposed system, are presented.


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