Abstract
This paper proposes a symmetrical phase-locked loop (PLL) that can eliminate the frequency-coupling terms caused by the asymmetric dynamics of conventional PLLs. In the approach, a concept of complex phase angle vector with both real and imaginary phase components is introduced, which enables to control the direct-and quadrature-Axis components with symmetrical dynamics. The small-signal impedance model that characterizes the dynamic effect of the symmetrical PLL on the current control loop is also derived, which, differing from the conventional multiple-input multiple-output impedance matrix, is in a single-input single-output (SISO) form based on complex transfer functions. This SISO representation allows for a design-oriented analysis. Moreover, the undesired sub-synchronous oscillation caused by the conventional asymmetrical PLL can be avoided, and the classical SISO impedance shaping can be utilized to cancel the negative resistor behavior caused by PLL; thus can greatly enhance the grid synchronization stability under weak grid conditions. The effectiveness of the theoretical analysis is validated by experimental tests.
Originalsprog | Engelsk |
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Artikelnummer | 8737995 |
Tidsskrift | IEEE Transactions on Power Electronics |
Vol/bind | 35 |
Udgave nummer | 2 |
Sider (fra-til) | 1473-1483 |
Antal sider | 11 |
ISSN | 0885-8993 |
DOI | |
Status | Udgivet - feb. 2020 |
Emneord
- Phase locked loops
- Impedance
- Stability analysis
- MIMO communication
- Power system stability
- Transfer functions
- Oscillators
- Frequency coupling
- PLL
- impedance modeling
- MIMO
- SISO impedance shaping