Patent ID: 8810976

Claim:
A harmonic protection apparatus for a capacitor bank, the harmonic protection apparatus including: a CPU unit; a current and voltage sampling unit coupled to the CPU unit and configured to provide current and voltage sampling of the capacitor bank; and a protection device controlled by the CPU unit and used for disconnecting the capacitor bank, wherein the CPU unit obtains effective value I 1 of fundamental wave current of the capacitor bank, and effective value I n of the n-th harmonic wave current of the capacitor bank, where n is harmonic order an ranges from 2 to ∞, and calculates the true effective value I of current of the capacitor bank according to the equation of I = I 1 2 + ∑ n = 2 ∞ ⁢ k n ⁢ I n 2 provided that k n =r n /r 1 , k n is the n-the harmonic coefficient, r n is power consumption equivalent resistance of the capacitor bank for the n-the harmonic, r 1 is power consumption equivalent resistance of the capacitor bank at a fundamental frequency; and when I≧1.3 I N , the CPU unit controls the protecting device to disconnect the capacitor bank, provided that I N is a threshold current of the capacitor bank.