A New Frequency-Adaptive Phase-Estimation Method Based on a New PLL Structure for Single-Phase Signals

Phase, frequency, and amplitude of single-phase voltages are the most important and basic information required for single-phase grid connected applications. This paper proposes a new method for estimating instantly and adaptively phase, frequency, and amplitude of frequency-varying single-phase signals for such applications, which is a new PLL method based on a new structure. The proposed method has the following attractive features: 1) the estimation system results in a nonlinear system, but it can be stabilized; 2) all subsystems constructing the system can be easily designed; 3) two-phase signal generator can tune a single system-parameter adaptively to varying frequency of the injected signal; 4) high order PLL-controllers allowing fast tracking can be stably used; 5) even in hostile envelopments, favorable instant estimates can be obtained. This paper proposes the estimation method, and verifies its usefulness by extensive numerical experiments.