A frequency measurement method, comprising: sampling a voltage to be measured with a fixed sampling frequency; obtaining a positive-sequence voltage angle change amount for a predetermined operation interval time by using a sampling sample obtained by the sampling and based on a Discrete Fourier Transform, DFT, calculation; obtaining a frequency offset amount by using the positive-sequence voltage angle change amount; and obtaining a frequency-related measurement value by using the frequency offset amount, wherein the frequency-related measurement value comprises at least one of a group consisting of a frequency measurement value and a frequency change rate measurement value, and the frequency offset amount is a difference between a rated frequency and the frequency measurement value, wherein the frequency-related measurement value comprises the frequency change rate measurement value, the method further comprising: comparing the frequency change rate measurement value with a threshold change rate; updating the frequency-related measurement value when the frequency change rate measurement value is less than the threshold change rate; stopping updating the frequency-related measurement value when the frequency change rate measurement value is greater than the threshold change rate, and characterized in that the method further comprises continuing to update the frequency-related measurement value when each frequency change rate measurement value is greater than the threshold change rate within a consecutive predetermined number of power cycles. sampling a voltage to be measured with a fixed sampling frequency; obtaining a positive-sequence voltage angle change amount for a predetermined operation interval time by using a sampling sample obtained by the sampling and based on a Discrete Fourier Transform, DFT, calculation; obtaining a frequency offset amount by using the positive-sequence voltage angle change amount; and obtaining a frequency-related measurement value by using the frequency offset amount, wherein the frequency-related measurement value comprises at least one of a group consisting of a frequency measurement value and a frequency change rate measurement value, and the frequency offset amount is a difference between a rated frequency and the frequency measurement value, wherein the frequency-related measurement value comprises the frequency change rate measurement value, the method further comprising: comparing the frequency change rate measurement value with a threshold change rate; updating the frequency-related measurement value when the frequency change rate measurement value is less than the threshold change rate; stopping updating the frequency-related measurement value when the frequency change rate measurement value is greater than the threshold change rate, and characterized in that the method further comprises continuing to update the frequency-related measurement value when each frequency change rate measurement value is greater than the threshold change rate within a consecutive predetermined number of power cycles. comparing the frequency change rate measurement value with a threshold change rate; updating the frequency-related measurement value when the frequency change rate measurement value is less than the threshold change rate; stopping updating the frequency-related measurement value when the frequency change rate measurement value is greater than the threshold change rate, and characterized in that the method further comprises continuing to update the frequency-related measurement value when each frequency change rate measurement value is greater than the threshold change rate within a consecutive predetermined number of power cycles.