1551-3203 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TII.2018.2856852, IEEE Transactions on Industrial Informatics Abstract—For transient stability studies of power systems with high penetration of microgrids, models of the connected microgrids must be used. In this paper, a novel dynamic equivalent model is proposed for grid-connected microgrids using measurement data of point of common coupling (PCC). The proposed equivalent model includes electrical components such as synchronous generator (SG), voltage source converter (VSC), active and reactive loads. The proposed equivalent model contains different controllers such as excitation system (EXS), governor and VSC’s controllers. All SG-based distributed generation (DG) units of the microgrid are represented by one equivalent SG while an equivalent VSC represents converters-based DGs. Similarly, a parallel active and reactive static load is considered in the equivalent model to represent the static loads of the microgrid. In order to make the equivalent model more efficient, accurate and valid at different operating points, a series resistance and reactance are utilized to connect the equivalent generator to the PCC. The final goal is to identify the parameters of the equivalent components such that the equivalent model behaves as like as the detailed microgrid facing different disturbances. The identification procedure is carried out by means of Genetic Algorithm (GA) using measurement data at the PCC. To show the effectiveness and accuracy of the proposed model, the identified equivalent model is studied at different operating points and the results are compared with the original detailed model. Index Terms—Equivalent model, Microgrid, Parameter estimation, Synchronous generator, Voltage source converter. NOMENCLATURE SG ω,δ Rotor speed and rotor angle. φ d , φ q Flux linkage of direct and quadratic axis. φfd Flux linkage of excitation winding. φ KD , φ KQ Flux linkage of d-q damper windings. H, D Rotor inertia and damping factor. Tm, Te, TD Mechanical, electrical and friction torque. ωb Base speed. v d , v q Voltage of direct and quadratic axis. i d , i q Currents of direct and quadratic axis. Efd, Ifd Voltage and current of excitation winding. iKD, iKQ Currents of d-q damper windings. x ld , x lq Leakage reactances of direct and quadratic axis. x lfd Leakage reactance of excitation winding. B. Zaker, G. B. Gharehpetian, and M. Karrari are with the Electrical Engineering Department of Amirkabir University of Technology, Tehran, Iran (e-mail: zaker.behrooz@aut.ac.ir, grptian@aut.ac.ir, karrari@aut.ac.ir). x lKD , x lKQ Leakage reactances of d-q damper windings. X d , X q Total reactances of direct and quadratic axis. X’d Transient reactance of direct axis. X”d, X”q Subtransient reactances of direct and quadratic axis. x fd Total reactance of excitation winding. x KD , x KQ Total reactances of d-q damper windings. xmd, xmq Mutual reactances of direct and quadratic axis. rs, rfd Resistances of stator and excitation windings. r KD , r KQ Resistances of d-q damper windings. T’ do Open circuit transient time constant. T”do T”qo Open circuit subtransient time constant. P g , Q g Generated active and reactive powers of SG. EXSs Tr Transducer time constant. Ki, Kir Regulator integral gains. K p , K pr Regulator proportional gains. K d , T d Regulator derivative gain and time constant. Km, Kff Inner loop forward and pre-control gains. Kg, Tg Regulator feedback gain and time constant. K im , K pm Inner loop proportional and integral gains. T a Controller time constant. GOV T 1 , T 2 , T 3 Controller first, second and derivative time constants. T 4 , T 5 , T 6 Actuator first, second and derivative time constants. Tdelay Combustion delay. Te Power feedback time constant. VSC K p , K q Proportional gain of power controllers. Tp, Tq Integral time constants of power controllers. Kpc, Kqc Proportional gain of current controllers. T pc , T qc Integral time constants of current controllers. P VSC , Q VSC Generated active and reactive powers of VSC. General R eq , X eq Resistance and reactance of the series branch. P ex , Q ex Signals of exchanged active and reactive powers at PCC of the simulated detailed microgrid. Pex ’ , Qe ’ Signals of exchanged active and reactive powers at PCC of the simulated equivalent model. P dgi , Q dgi Active and reactive generated powers of ith DG. cp, cq Equivalent load correction factors. NDG Number of DGs. N Number of samples. , SS  Pure and noisy signal. A Novel Measurement-Based Dynamic Equivalent Model of Grid-Connected Microgrids B. Zaker, G. B. Gharehpetian, Senior Member, IEEE, and M. Karrari, Senior Member, IEEE