Harmonic pollution in power grids is primarily caused by nonlinear loads (such as power electronic equipment and inverters). These loads inject large amounts of harmonic current into the grid during operation, causing voltage waveform distortion and, in turn, impacting the normal operation of power equipment and grid stability.
The static var generator (SVG), as an advanced dynamic reactive power compensation device, effectively addresses harmonic pollution in power grids through its unique power electronics technology and control strategy. The core of the SVG lies in its use of turn-off power electronic devices (such as IGBTs) to form a self-commutated bridge circuit. By adjusting the amplitude and phase of the bridge circuit's AC output voltage or directly controlling its AC current, it achieves rapid and continuous reactive power regulation. This feature enables the SVG to not only track the inrush current of inrush loads but also dynamically track and compensate for harmonic currents. When harmonics are present in the power grid, the SVG monitors the harmonic components in real time and precisely generates a compensating current of equal magnitude and opposite phase to the harmonic current, thereby canceling the harmonic current and achieving harmonic mitigation.
The SVG's harmonic mitigation capabilities stem from its advanced control algorithms and detection technology. SVG typically uses algorithms such as Fast Fourier Transform (FFT) or Wavelet Transform to perform spectral analysis on current and voltage signals, accurately extracting the amplitude and phase information of each harmonic. Based on this information, the SVG's control strategy (such as deadbeat control, hysteresis control, or sliding mode control) adjusts the output voltage or current in real time to ensure precise matching of the compensation current with the harmonic current. This dynamic adjustment capability gives SVG a significant advantage in harmonic suppression, making it particularly suitable for power grids with complex and dynamically changing harmonic components.
Compared to traditional reactive power compensation devices (such as capacitor banks and SVCs), SVG offers unique advantages in harmonic mitigation. Traditional devices, due to their capacitive compensation, not only fail to filter harmonics but can even amplify them due to the resonant characteristics of the capacitors, leading to increased harmonic pollution.
As an active compensation device, SVG does not generate or amplify harmonics. It actively injects compensation current to directly offset harmonic components in the system, filtering out over 50% of harmonics. SVG also enables continuous reactive power regulation, providing stepless compensation starting from 0.1 kvar, completely avoiding the over- or under-compensation issues associated with traditional step-by-step switching, further improving power quality.
SVG's harmonic control capabilities are widely valuable in practical applications. In the industrial sector, a large number of nonlinear loads (such as inverters and arc furnaces) cause severe harmonic pollution. SVG significantly improves grid quality and ensures stable operation of production equipment by compensating for these harmonics in real time. In the renewable energy sector, with the widespread integration of new energy sources such as wind power and photovoltaics, harmonic issues in the power grid are becoming increasingly complex. The application of SVG in renewable energy power generation systems effectively suppresses harmonic propagation and improves the quality of renewable energy grid integration. In urban distribution networks, the use of SVG not only reduces harmonic damage to power equipment but also improves energy efficiency, providing strong support for the development of smart grids.
SVG's harmonic control effectiveness is also reflected in its comprehensive improvement of other grid issues. For example, SVG can monitor and adjust system voltage in real time to maintain voltage stability, thereby reducing the impact of voltage fluctuations and flicker on equipment and systems. Furthermore, when three-phase imbalance exists in the power system, SVG can independently adjust the current output of each phase to achieve a balanced three-phase current state, further improving grid stability and reliability.
The static var generator (SVG) effectively manages grid harmonic pollution through its advanced power electronics, control algorithms, and detection technologies. Its dynamic regulation capabilities, stepless compensation characteristics, and comprehensive improvements to other grid issues make SVG an ideal choice for addressing grid harmonic pollution.
