The fundamental cause of harmonic generation is due to nonlinear loads. When the current flows through the load and does not have a linear relationship with the applied voltage, it forms a non sinusoidal current, resulting in harmonics. The suppression of harmonics in the power system is to reduce or eliminate the harmonic current injected into the system, in order to control the harmonic voltage within the specified value.

There are four main measures to suppress harmonic currents:

1. Reduce the harmonic content of the harmonic source. That is to take measures on the harmonic source to avoid the generation of harmonics. This method is more proactive, can improve the quality of the power grid, and can greatly save the cost of eliminating harmonic effects.

2. Adopting pulse width modulation (PWM) method. By using Pulse Width Modulation (PWM) technology, the DC voltage is modulated into a series of AC voltage pulses of equal amplitude but not equal width within the required frequency cycle. This method can greatly suppress the generation of harmonics.

3. Absorb harmonic current at the harmonic source. This type of method is an effective way to suppress existing harmonics, which is currently widely used in the power system to suppress harmonics.

4. Improve the power supply system and environment. For the power supply system, the generation of harmonics is inevitable, but measures such as increasing the short-circuit capacity of the power supply system, improving the voltage level of the power supply system, increasing the capacity of power supply equipment, and maintaining three-phase load balance as much as possible can all improve the ability of the power grid to resist harmonics. Choosing a reasonable power supply voltage and maintaining three-phase voltage balance as much as possible can effectively reduce the impact of harmonics on

the power grid. The harmonic source is supplied by a larger capacity power supply point or a higher voltage grid, and the ability to withstand harmonics will increase. Powering the harmonic source load through dedicated lines reduces the impact of harmonics on other loads, and also helps to concentrate the suppression and elimination of higher-order harmonics.