5048 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 59, NO. 4,JULY/AUGUST 2023 Small Hydro Based Grid Forming Converter Having Power Sharing and Synchronization Capability With DFIG Based WECS Shalvi Tyagi , Member, IEEE, Bhim Singh , Fellow, IEEE, and Souvik Das , Member, IEEE Abstract—In the presence of the utility grid, the inverter based resources such as wind, hydro and photovoltaic operate in the grid following mode, as the voltage and frequency are assigned by the utility grid. However, in remote areas, where the presence of grid is challenging, it is required to maintain stiff voltage and frequency at the point of common interconnection of loads in standalone mode. In this work, a unique configuration comprising doubly fed induction generator (DFIG) based wind energy conversion system (WECS), small hydro-solar photovoltaic (SH-PV) based hybrid microgrid is presented, where the local grid is formed by the SH-PV system combined with a battery energy storage (BES). Switching logics are developed for the small hydro based grid forming, machine side and load side converters in such a way that synchronization of the WECS with the SH-PV is smooth. Besides, active filter operation of the load side converter is also demonstrated. The proposed microgrid is tested under various transitional modes and gives an insight of interactions between these inverter based renewable energy sources. The hybrid mi- crogrid presented depicts bidirectional flow of power. This way uninterrupted power is supplied to the local loads and also supports noncritical loads. The work concludes with a laboratory prototype to illustrate the operation of hybrid microgrid in numerous modes. Index Terms—Batteries, microgrid, small hydro power generation, solar photovoltaic (spv) power generation synchronization, wind power generation. NOMENCLATURE P h ,v habc ,i habc Small hydrogenerator power, voltages, currents. V DC1 DC link-I voltage. V ∗ hm ,V hm ,V ∗ hme Reference amplitude of small hydrogen- erator voltage, estimated amplitude of PCL voltage, error in voltage. Manuscript received 3 December 2022; revised 27 January 2023; accepted 24 February 2023. Date of publication 27 March 2023; date of current version 19 July 2023. Paper 2022-IACC-1479.R1, presented at the 2022 IEEE Global Conference on Computing, Power and Communication Technologies (Glob- ConPT), New Delhi, India, Sept 23–Sept 25, 2022, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Industrial Automation and Control Committee of the IEEE Industry Applications Society [DOI: 10.1109/GlobConPT57482.2022.9938186]. This work was supported in part by the SERB-NSC Fellowship, Department of Science and Technology, Government of India, for project SERI-II under Grant RP03357 and in part by the FIST under Grant RP03391G. (Corresponding author: Shalvi Tyagi.) The authors are with the Department of Electrical Engineering, In- dian Institute of Technology Delhi, New Delhi 110016, India (e-mail: tyagi.shalvi@gmail.com; bsingh@ee.iitd.ac.in; souvik.das.926@gmail.com). Color versions of one or more figures in this article are available at https://doi.org/10.1109/TIA.2023.3261863. Digital Object Identifier 10.1109/TIA.2023.3261863 x pv ,x iv Proportional and integral gains of voltage controller. f ∗ h ,f h ,f he Reference small hydrogenerator fre- quency, sensed small hydrogenerator fre- quency, error in frequency. x pf ,x if Proportional and integral gains of PCL frequency controller. ω href , θ h fixed frequency of small hydrogenerator, phase angle of small hydrogenerator. v ∗ GF C ,m ql Reference PCL voltages, output of volt- age feedback loop. S s Synchronizing signal. v sabc ,i sabc , θ s Three phase stator voltages, stator cur- rents, phase angle of DFIG. i rabc , θ r , θ slip Three phase rotor currents, phase angle of rotor, slip angle of DFIG. v w Wind speed in m/s. V sm Amplitude of stator voltage of DFIG. Δv, Δθ Error between reference and sensed am- plitude of voltage at PCL, error between small hydrogenerator phase angle and sta- tor phase angle of DFIG. I ∗ dr ,I ∗ qr Reference reactive and active compo- nents of rotor current of DFIG. x pvt ,x ivt Proportional and integral gains of voltage controller. ω ref , ω c Reference frequency, compensating fre- quency. x pθ ,x iθ Proportional and integral gains of phase controller. ω est , ω er Estimated frequency, error in reference frequency and estimated frequency. x pω ,x iω Proportional and integral gains of fre- quency controller. Q ∗ s ,Q s ,q err Reference reactive power, sensed reactive power, error in reactive power. x pq ,x iq Proportional and integral gains of reactive power controller. ω ∗ r ,ω r ,ω re Reference rotor speed of DFIG, sensed rotor speed of DFIG, error in rotor speed. x pωr ,x iωr Proportional and integral gains of speed controller. V ∗ DC2 ,V DC2 ,V DCe Reference DC link-2 voltage, sensed DC link-2 voltage, DC link-2 voltage error. 0093-9994 © 2023 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See https://www.ieee.org/publications/rights/index.html for more information. Authorized licensed use limited to: INDIAN INSTITUTE OF TECHNOLOGY DELHI. Downloaded on November 29,2023 at 12:09:47 UTC from IEEE Xplore. Restrictions apply.