Secondary Control for Voltage Quality Enhancement in Microgrids

IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society

Guerrero

et al. 2017

Self Cite

Abstract-Fault current limiters (FCLs) are one class of solutions to cope with the upcoming challenges in microgrid protection. Considering high penetration of distributed generations (DGs) in microgrids, the necessity of designing cheap and effective FCL is getting higher. This paper attempts to fill this gap by proposing an embedded FCL operating based on modifying the secondary control of DGs. As this method is designed for fourwire system, besides cost-effectiveness, it has independency and flexibility to only limit the fault current of DG. In order to validate the proposed method, different types of faults are examined through an extensive simulation study.

Section: A Three-phase Four-wire Control Systemmentioning

confidence: 99%

A secondary-control based fault current limiter for four-wire three phase inverter-interfaced DGs

Beheshtaein

IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society

Guerrero

et al. 2017

Self Cite

“…In addition, a feedforward loop is included in order to take the small variations of dc link voltage (V dc ) into account. Details about droop controllers and voltage/current loops can be found in [9] and [11].…”

Section: Proposed Control Structurementioning

confidence: 99%

“…The methods presented in [5]- [8] are designed for compensation of voltage unbalance or harmonics at each DG terminal while usually it is preferred to have a good power quality at "Sensitive Load Bus (SLB)" of the microgrid. Based on this, a hierarchical structure is presented in [9] to enhance voltage quality at SLB.…”

Section: Introductionmentioning

confidence: 99%

“…This way, the voltage quality after the LCL filter is improved, noticeably. Moreover, the control structure is much simpler than hierarchical scheme of [9]. However, the quality of SLB voltage is not controlled in [10] and it can be a problem, if SLB is electrically far from the LCL filter output.…”

Section: Introductionmentioning

confidence: 99%

“…In the proposed scheme, secondary controller determines the virtual capacitances which should be inserted for negative sequence of fundamental component and for main harmonic orders (here 3 rd , 5 th and 7 th harmonics) in a selective way. Note that in the case of unbalanced loading, triplen harmonics will also have positive and negative sequences [9]. The control objective is to reduce SLB voltage distortion to the desired level.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Adaptive virtual impedance scheme for selective compensation of voltage unbalance and harmonics in microgrids

2015 IEEE Power &Amp; Energy Society General Meeting

Shafiee

Vasquez

et al. 2015

Self Cite

Abstract-This paper presents a two-level hierarchical control approach for voltage source inverters used to interface Distributed Generators (DGs) in microgrid applications. The control structure comprises primary and secondary levels. The primary level is a local controller, which consists of voltage and current inner control loops in order to fix the filter capacitor voltage and a virtual impedance loop mainly for voltage harmonics and unbalance compensation. The virtual impedance is set by the central secondary controller to mitigate the voltage distortion at sensitive load bus (SLB). Secondary controller is connected to a measurement unit to obtain the data of voltage harmonics and unbalance at microgrid SLB and broadcasts the commands for adjusting the virtual impedance of each unit. A general case with a combined voltage harmonic and unbalance distortion is considered. In such a case, voltage distortion is mitigated by selective insertion of capacitive virtual impedances for negative sequence of fundamental component as well as positive and negative sequences of main harmonics. The values of virtual capacitances are determined based on the required voltage quality at the load bus; thus, this scheme is titled as adaptive virtual impedance. Experimental results are presented to demonstrate the effectiveness of the proposed control approach.

Distributed optimal voltage control in islanded microgrids

Mobashsher

Keypour

Int Trans Electr Energ Syst

2021

Self Cite

This paper introduces an optimal voltage control (OVC) framework for islanded microgrids (MGs) as a unified hierarchical control scheme, started from bus voltage set-points optimization at tertiary level, then effectively followed by secondary control, which controls the distributed energy resources via their primary level controllers. The distributed control structure is proposed here for both tertiary and secondary levels to benefit from higher reliability, avoidance of a single point of failure, and a relatively simple communication system. At the tertiary level, a new distributed voltage protocol, based on the Lyapunov theory, is proposed to optimize power losses and voltage profile deviations in the MG. The obtained optimal voltage references are passed to the secondary level, in which a modified distributed protocol (MDP) is utilized to ensure the OVC and dynamic stability. In addition, the proposed MDP can maintain the critical bus voltage against load changes until the next optimal set-point updates. The performance of the MDP is examined for different scenarios such as load changes and DGs plug and play operation in the MATLAB/Simulink environment.