Harmonic protection device for capacitor bank

The invention provides a harmonic protection device for a capacitor bank. The harmonic protection device comprises a CPU unit, a current and voltage sampling unit and a protection device, wherein the CPU unit calculates the true root mean square I of a current on the capacitor bank after obtaining the root mean square I1 of a fundamental current and the root mean square In of each subharmonic on the capacitor bank, and when I is larger than 1.3 IN, the capacitor bank is turned off by the protection device under the control of the CPU unit; IN is the rated current of the capacitor bank. The harmonic protection device not only can realize conventional protection functions on over-current, over-voltage and the like, but also can calculate 2-13 subharmonics in the current and voltage in real time, comprehensively provide harmonic protection functions on the single harmonic current, single harmonic voltage, full current, full voltage and the like, and better provide protection for the capacitor bank.