Abstract:

As the application of frequency converter in auxiliary power, the requirements of frequency conversion transformation of highvoltage motors and variable frequency differential protection are increasing. Taking the frequency conversion transformation of condensate pump motor as an example，this paper introduced the transformation scheme of differential protection and the nonpower frequency tracking sampling value differential algorithm it adopted, and verified its sampling performance and protection reliability by experiments, which provided a reference for the differential protection transformation of a highvoltage variablefrequency motor.

Key words: high voltage motor；frequency converter, frequency tracking, sampling value differential protection