How to Deal with Harmonic Amplification After the Commissioning of Solar Power Generation Systems

1. Main Causes of Harmonic Amplification in Solar Power Generation Systems

1) Non-linear output of inverters

Solar power generation systems rely on inverters to convert DC power into AC power. During the high-speed switching process of inverters, a certain proportion of high-frequency harmonic components will be generated. When multiple solar power generation systems are connected in a concentrated manner, the harmonic currents may be superimposed and amplified.

2) Resonance caused by system impedance variation

After the grid connection of solar power generation systems, the original power grid impedance structure will be changed. If reactive power compensation devices or capacitor banks exist on site, new resonant frequency points may be formed, thereby amplifying specific-order harmonics.

2. Hazards of Harmonic Amplification in Solar Power Generation Systems

1) Increased temperature rise of electrical equipment

Harmonic currents will increase line losses and intensify the heating of transformers, cables and compensation capacitors. Long-term operation of solar power generation systems in a high-harmonic environment may significantly shorten the service life of equipment.

2) Deterioration of power quality

When the harmonic distortion rate exceeds the standard, malfunctions or unstable operation may occur in sensitive equipment. Although solar power generation systems improve energy utilization efficiency, inadequate harmonic control will instead affect the overall power supply quality.

3. Solutions to Harmonic Amplification in Solar Power Generation Systems

1) Installation of active filtering devices

For scenarios with high harmonic currents, active power filters (APF) can be installed at the grid connection point of the solar power generation system. This equipment can detect harmonic components in real time and output reverse compensation currents to effectively reduce the distortion rate.

2) Optimization of reactive power compensation configuration

If the original system is equipped with capacitor banks, the compensation capacity and reactance rate should be re-evaluated. Series reactors or adjusted compensation schemes can be adopted to avoid resonance between the solar power generation system and capacitors.

3) Analysis of grid-connected capacity and layout

In large parks or centralized photovoltaic projects, the grid-connected capacity and access location of solar power generation systems should be reasonably planned. Avoiding centralized access of multiple devices to the same node helps reduce the risk of harmonic superposition.