The invention discloses a
voltage frequency tracking method for
distributed power grid-connected
inverter protection. The method comprises steps: real-time sampling is carried out on
voltage at the port of the
inverter in the
distributed power grid, and the sampling frequency is fixed to be 600Hz; the
voltage sampling value is inputted to the
inverter in real time, iterative computation is carried out, and a frequency
estimation value is corrected; the frequency
estimation value is sent to an inverter protection circuit in real time for participating in logic judgment, and after the
system voltage frequency deviates from a
normal range and certain
delay is reached, the inverter protection action outlet isolates the
distributed power and a main
power grid system. The voltage frequency tracking method for distributed
power grid-connected inverter protection has the beneficial effects that compared with the traditional Fourier principle-based frequency measurement technology, the time
delay problem of frequency tracking can be solved from the aspect of the principle, tracking is stronger in real-time performance, convergence is quick and stable, and
time limit requirements on inverter protection can be reliably met. As the
fixed frequency is adopted for sampling, selection of the sampling frequency has little effect on calculation precision, and to a certain degree, calculation amount of the
algorithm is saved.