An improved power control strategy for grid‐connected hybrid microgrid without park transformation and phase‐locked loop system

Abstract

Summary Voltage source converters are important elements of grid‐connected microgrid, as these integrate distribution generators of microgrid with utility grid. Often due to lack of efficient and flexible control, these converters do not perform as per expectations. Many control methods based on dq current control theory had been developed for grid‐connected microgrids inverters to control power flow between microgrid and grid. However, all these controllers used phase locked loop systems for grid synchronization purposes, which possess slow dynamics and transient response. To overcome these issues, in this article, an improved real and reactive power control method for grid‐connected hybrid microgrid's bidirectional voltage source converter is proposed which is based on the dq current control theory without using phase locked loop system and Park transformation. The proposed power controller has possessed better dynamic performance compared with the conventional power controllers consisted of phase locked loop system. In addition, due to the elimination of phase locked loop system and park transformation not only the computational burden is reduced with the implementation of the proposed power controller, but also steady state performance is enhanced. The control hardware‐in‐loop real time simulation is carried out using real time digital simulator to validate the performance of the proposed power controller during transient state, steady state and power transfer mode by modeling a grid‐connected hybrid microgrid. From the simulation results, it has been observed that the settling time has improved to 0.08 second compared to 0.15 second of conventional controller, power ripples are significantly reduced, and total harmonic distortion of converter output current obtained is 2.226%.

Enhancing Stability of Grid-Supporting Inverters from an Analytical Point of View with Lessons from Microgrids

“…For this, the voltage at the inverter terminals is measured and then transformed via dq transformation to gain the phase angle as well as the PLL frequency used as the reference value for the f/P loop. The same voltage is also transformed via alpha-beta transformation to calculate V abs as the reference value for the V/Q relation, since alpha-beta transformation depicts better stability than dq transformation [25]. Pm and Qm are calculated with the power relation in the alpha-beta domain, following this formula:…”

Direct Power Control Based on Point of Common Coupling Voltage Modulation for Grid-Tied AC Microgrid PV Inverter

“…By using the available modules from RSCAD library for various MG components, the AC MG is modeled and these components mathematical modeling adopted from [26]. The specifications of all the MG components are presented in Appendix Table IA.…”

“…To circumvent the PLL system's limitations, some studies [23][24][25] proposed frequency locked loop (FLL)-based synchronization solution for the MG's VSI [23][24][25]. Power control approach based on PLL-less CCT is introduced in [26] for grid-tied hybrid MG's VSI. Although power tracking performance of these control systems have improved marginally, there are still undesired ripples observed in both real and reactive powers.…”

Application and Optimization of Luenberger Observer Phase-Locked Loop and Inductance-Free Vector Control Method for Aviation Three-Phase Converter in Wearable Equipment

“…A small-signal model of the Luenberger observer phase-locked loop is established to collect main research data through real-time operation during the stability analysis and parameter design of the Luenberger observer phase-locked loop. Figure 5 shows the small-signal model of the phase-locked loop of the Luenberger observer designed here [ 23 ].…”