scholarly journals The new power sharing method for threephase parallel inverters with nonlinear loads

2015 ◽  
Vol 18 (1) ◽  
pp. 16-28
Author(s):  
Phuong Minh Le ◽  
Dai Tan Le ◽  
Hoa Thi Xuan Pham
Keyword(s):  
Reactive Power ◽  
Energy System ◽  
Active Power ◽  
Power Sharing ◽  
Control Loop ◽  
Output Impedance ◽  
Nonlinear Loads ◽  
Control Scheme ◽  
Virtual Impedance

This paper presents a new method for controling parallel inverters to share active power and reactive power in the energy system with non-linear loads. In these systems, the virtual output impedance is usually added to the control loop of each inverter to improve the active power and reactive power sharing as well as the quality of the voltage system. Paper also proposes a kind of virtual impedance as a second-order general-integrator (SOGI) scheme. The simulation results in Matlab Simulink show the ability of the proposed controller to good share power P-Q, when connected with unbalanced and nonlinear loads. By using the proposed algorithm allows to reduce the voltage THD to 1.9% and 1.2% for unbalanced and nonlinear loads according by comparision with traditional control scheme.

scholarly journals Hysteresis Control for Shunt Active Power Filter under Unbalanced Three-Phase Load Conditions

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Z. Chelli ◽  
R. Toufouti ◽  
A. Omeiri ◽  
S. Saad
Keyword(s):  
Reactive Power ◽  
Harmonic Distortion ◽  
Active Power Filter ◽  
Active Power ◽  
Harmonic Suppression ◽  
Nonlinear Loads ◽  
Shunt Active Power Filter ◽  
Power Filter ◽  
Three Phase ◽  
Control Scheme

This paper focuses on a four-wire shunt active power filter (APF) control scheme proposed to improve the performance of the APF. This filter is used to compensate harmonic distortion in three-phase four-wire systems. Several harmonic suppression techniques have been widely proposed and applied to minimize harmonic effects. The proposed control scheme can compensate harmonics and reactive power of the nonlinear loads simultaneously. This approach is compared to the conventional shunt APF reference compensation strategy. The developed algorithm is validated by simulation tests using MATLAB Simulink. The obtained results have demonstrated the effectiveness of the proposed scheme and confirmed the theoretical developments for balanced and unbalanced nonlinear loads.

SPV-Based UPQC with Modified Power Angle Control Scheme for the Enhancement of Power Quality

2019 ◽  
Vol 29 (04) ◽  
pp. 2050064 ◽  
Author(s):  
A. Gowrishankar ◽  
M. Ramasamy
Keyword(s):  
Power Quality ◽  
Reactive Power ◽  
Dynamic Performance ◽  
Digital Simulation ◽  
Energy System ◽  
Active Power ◽  
Solar Irradiation ◽  
Prototype Model ◽  
Synchronous Reference Frame ◽  
Control Scheme

Unified Power Quality Conditioner (UPQC) with a modified Power Angle Control (PAC) scheme is presented for effective interconnection of renewable energy system into the grid. The UPQC consists of both shunt and series Active Power Filters (APFs). The shunt and series APF is one of the most effective custom power devices, which provides compensation for current and voltage-based disturbances, respectively. The shunt APF supplies active power to the load from the Distributed Generation (DG) in addition to reactive power demand supplied by it. Because of this functionality, the Volt–Ampere (VA) burden increases along with the rating of the shunt inverter. The PAC scheme aims to effective utilization of series and shunt APFs through sharing of reactive power to reduce VA burden on shunt APF. The PAC scheme is based on Synchronous Reference Frame (SRF) theory, which has simple computations, is robust and uses existing measurements of Solar Photovoltaic (SPV)-integrated UPQC. The performance of the proposed SPV-integrated UPQC is verified with the manifestation of nonlinear loads and reactive burdens with the SPV power generating system. The dynamic performance of the PV-UPQC is verified under the grid disturbances such as voltage sag, swell, varying load and change in solar irradiation. The effectiveness of the proposed control scheme is evaluated through the digital simulation and hardware experimental prototype model.

scholarly journals Autonomous microgrid based parallel inverters using droop controller for improved power sharing

2020 ◽  
Vol 9 (6) ◽  
pp. 2302-2310
Author(s):  
Siddaraj Siddaraj ◽  
Udaykumar R. Yaragatti ◽  
Nagendrappa H. ◽  
Vikash Kumar Jhunjhunwala
Keyword(s):  
Energy Source ◽  
Reactive Power ◽  
Active Power ◽  
Power Sharing ◽  
Voltage Source ◽  
Voltage Source Inverters ◽  
Distributed Generators ◽  
Current Controller ◽  
Power Frequency

The existing microgrid has become a challenge to the sustainable energy source to provide a better quality of power to the consumer. To build a reliable and efficient microgrid, designing a droop controller for the microgrid is of utmost importance. In this paper, multiple voltage source inverters connected in parallel using an active power-frequency/reactive power-voltage droop scheme. The proposed method connected to two distributed generators local controllers, where each unit consists of a droop controller with an inner voltage-current controller and a virtual droop controller. By adding this controller to the microgrid reliability and load adaptability of an islanded system can be improved. This concept applied without any real-time communication to the microgrid. Thus, simulated using MATLAB/Simulink, the obtained results prove the effectiveness of the autonomous operation's microgrid model.

scholarly journals Multiloop low bandwidth communication-based power sharing control for microgrids

2020 ◽  
Vol 21 (2) ◽  
pp. 682
Author(s):  
Erum Pathan ◽  
Afarulrazi Abu Bakar ◽  
Mubashir Hayat Khan ◽  
Muhammad Asad ◽  
Haider Arshad
Keyword(s):  
Reactive Power ◽  
Power Sharing ◽  
Control Technique ◽  
Voltage Source ◽  
Computational Burden ◽  
Voltage Source Inverters ◽  
Control Techniques ◽  
Equivalent Impedance ◽  
Control Scheme ◽  
Virtual Impedance

<span>In parallel-connected inverter-based microgrids, the reactive power sharing accuracy can not have satisfactory results effortlessly. Mismatch in feeder impedances of the parallel-connected inverter-based microgrids is a significant cause of inaccurate reactive power-sharing. In voltage source inverters (VSI) based microgrids, especially for the islanded mode of operation, the conventional centralized or decentralized control techniques are not much helpful to control the voltage deviations due to impedance mismatch. Mismatch of the feeder impedance is compensated by the addition of fixed virtual impedance. Whereas, the change in the virtual impedance is compensated by adaptive virtual impedance-based control techniques which are helpful to mitigate power-sharing errors, but in most of the control schemes virtual impedance-based control mechanism needs pre-knowledge of feeder impedance which increases the computational burden. This paper presents a decentralized virtual impedance-based power sharing control. In the proposed control solution to mitigate reactive power sharing errors in distributed generation (DG) units, mismatch of the parallel-connected feeder impedance is equalized by regulating the addition of equivalent impedance to each DG inverter. Proposed control technique offers an independent implementation without any pre-knowledge of the feeder impedance. Hence, the implementation of the control scheme is a straightforward and computational burden is also reduced. Simulation results show the effectiveness of the control scheme. </span>

scholarly journals Coordinated Control for Large-Scale Wind Farms with LCC-HVDC Integration

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2207 ◽  
Author(s):  
Xiuqiang He ◽  
Hua Geng ◽  
Geng Yang ◽  
Xin Zou
Keyword(s):  
Large Scale ◽  
Reactive Power ◽  
Wind Farms ◽  
Coordinated Control ◽  
Active Power ◽  
Phase Plane Analysis ◽  
Control Loop ◽  
Control Loops ◽  
Hvdc Transmission ◽  
Control Scheme

Wind farms (WFs) controlled with conventional vector control (VC) algorithms cannot be directly integrated to the power grid through line commutated rectifier (LCR)-based high voltage direct current (HVDC) transmission due to the lack of voltage support at its sending-end bus. This paper proposes a novel coordinated control scheme for WFs with LCC-HVDC integration. The scheme comprises two key sub-control loops, referred to as the reactive power-based frequency (Q-f) control loop and the active power-based voltage (P-V) control loop, respectively. The Q-f control, applied to the voltage sources inverters in the WFs, maintains the system frequency and compensates the reactive power for the LCR of HVDC, whereas the P-V control, applied to the LCR, maintains the sending-end bus voltage and achieves the active power balance of the system. Phase-plane analysis and small-signal analysis are performed to evaluate the stability of the system and facilitate the controller parameter design. Simulations performed on PSCAD/EMTDC verify the proposed control scheme.

Effective Communication-Based Reactive Power Sharing Scheme for Meshed Microgrid in an Islanded Mode

2021 ◽  
Author(s):  
Anitha Daniel ◽  
Suchitra Dayalan
Keyword(s):  
Power System ◽  
Reactive Power ◽  
Local Area ◽  
Power Sharing ◽  
Matlab Simulation ◽  
Distributed Generators ◽  
Control Scheme ◽  
Islanded Mode ◽  
Radial Network ◽  
Virtual Impedance

Microgrids (MGs) are the most sought out and feasible solution for the present energy crisis. MG is a group of Distributed Generators (DGs) interacting with each other to provide energy to a defined local area. The inclusion of DGs into the conventional power system at various voltage levels has altered the topology of the power system and their control techniques. Hence, the MGs can no longer be considered as a traditional radial network but rather a meshed network. The control and operation of such practical MGs become a challenge, especially when operated in the islanded mode. This research paper considers a realistic meshed MG operating in an islanded mode for study. In an islanded MG, the issues of real and reactive power sharing among DGs are addressed so that the power contribution of each DG is proportional to its rating, thus preventing overload and ensuring reliable operation. A communication-based virtual impedance estimation is proposed in addition to the droop controller for proportionate real and reactive power sharing among DGs in a meshed MG. With the increased complexity of meshed MG, the proposed communication-based control scheme offers an efficient reactive power sharing between DGs without the feeder and network impedance requirements. A MATLAB simulation study proves the effectiveness of the proposed control strategy for a meshed MG with equal DG ratings and unequal DG ratings under changing load conditions.

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