STATCOM and Voltage Flicker Mitigation

What is votlage flicker?

Voltage flicker refers to the rapid and repeated fluctuations in the voltage level of a power supply, which can cause noticeable changes in the intensity of lighting and can affect the performance of other electrical equipment. These fluctuations can be annoying and may lead to operational issues in sensitive equipment

Causes of Voltage Flicker

Rapidly Varying Loads:

Electric Arc Furnaces (EAF): These are common in steel manufacturing and cause significant flicker due to their highly variable load.

Welding Machines: Welding operations often involve rapidly changing current demands, causing voltage flicker.

Large Motors: The starting and stopping of large motors can create substantial changes in load, leading to voltage fluctuations.

Intermittent Renewable Energy Sources:

Wind Turbines: The power output from wind turbines can vary quickly with changing wind speeds, leading to flicker.

Solar Panels: Rapid changes in solar irradiance, such as passing clouds, can cause fluctuations in power output.

Faults and Switching Operations:

Short Circuits and Faults: Faults in the network can cause sudden drops or rises in voltage.

Switching Operations: Switching operations in the power network can lead to transient voltage variations.

Effects of Voltage Flicker

Lighting Fluctuations:

Visible Flicker: Changes in light intensity can be perceived by the human eye, which can be particularly annoying in environments with sensitive lighting, such as offices and homes.

Health Issues: Prolonged exposure to flickering lights can cause discomfort, headaches, and visual fatigue.

Equipment Performance:

Sensitive Equipment: Electronic devices, computers, and other sensitive equipment may malfunction or suffer from reduced performance due to voltage flicker.

Process Interruption: Industrial processes relying on stable power can be disrupted, leading to production losses.

Increased Wear and Tear:

Electrical Components: Frequent voltage fluctuations can lead to increased wear and tear on electrical components, reducing their lifespan and increasing maintenance costs.

Measuring Voltage Flicker

Pst (Short-Term Flicker Severity):

Pst is a measure of the perceptibility of flicker to the human eye over a 10-minute period. A Pst value of 1 indicates the threshold at which flicker becomes annoying to the average person.

Plt (Long-Term Flicker Severity):

Plt is the average value of Pst over a 2-hour period, providing a measure of the long-term impact of flicker.

How STATCOM Mitigates Voltage Flicker

Voltage flicker refers to the rapid and repeated changes in the voltage level of a power supply, which can cause noticeable changes in the intensity of lighting and other electrical equipment. These fluctuations can be caused by rapidly varying loads, such as electric arc furnaces, welding machines, and large motors starting and stopping. STATCOM (Static Synchronous Compensator) can effectively realize voltage flicker reduction and improve power quality.

Dynamic Reactive Power Compensation:

Rapid Response: STATCOMs provide fast and dynamic reactive power compensation. By quickly adjusting the amount of reactive power injected or absorbed, STATCOMs can smooth out voltage fluctuations.

Instantaneous Control: The voltage source converter (VSC) in a STATCOM can respond within milliseconds, which is essential for mitigating rapid voltage changes that cause flicker.

Voltage Stabilization:

Voltage Support: STATCOMs stabilize the voltage at the point of common coupling (PCC) by maintaining the voltage within specified limits. This helps in reducing the amplitude of voltage fluctuations.

Steady Voltage Levels: By providing continuous voltage support, STATCOMs ensure that the voltage remains steady even when there are rapid changes in load.

Harmonic Filtering:

Reduction of Harmonics: Although primarily designed for reactive power compensation, STATCOMs can also help in reducing harmonic distortions that might accompany voltage flicker.

Cleaner Waveform: By reducing harmonics, STATCOMs contribute to a cleaner voltage waveform, which can help mitigate flicker caused by distorted waveforms.

Load Balancing:

Phase Balancing: STATCOMs can help in balancing the load across different phases in a three-phase system, which can reduce voltage imbalances that contribute to flicker.

Even Distribution: Ensuring an even distribution of loads helps in maintaining a stable voltage profile, thereby reducing flicker.

Applications of STATCOM for Flicker Mitigation

Industrial Plants:

Electric Arc Furnaces (EAF): In steel plants, EAFs are significant sources of voltage flicker. STATCOMs are commonly used to stabilize voltage and reduce flicker during the melting process.

Welding Operations: Welding machines can cause rapid voltage changes. STATCOMs provide the necessary reactive power support to mitigate flicker in welding operations.

Renewable Energy Integration:

Wind Farms: The intermittent nature of wind energy can cause voltage fluctuations. STATCOMs help in smoothing these fluctuations and maintaining voltage stability.

Solar Farms: Rapid changes in solar irradiance can lead to voltage flicker. STATCOMs assist in stabilizing the voltage output of solar farms.

Urban and Residential Areas:

Grid Stability: In areas with a high density of sensitive electronic equipment, STATCOMs ensure stable voltage levels, reducing flicker and protecting equipment.

Benefits of Using STATCOM for Flicker Mitigation

Improved Power Quality: By reducing voltage flicker, STATCOMs enhance overall power quality, which is crucial for the reliable operation of sensitive equipment.

Increased Equipment Lifespan: Reducing voltage fluctuations decreases the stress on electrical equipment, leading to longer operational life and reduced maintenance costs.

Enhanced Comfort: In residential and commercial areas, mitigating voltage flicker improves the comfort and satisfaction of occupants by providing stable lighting and power supply.

Compliance with Standards: Using STATCOMs helps in complying with power quality standards and regulations, avoiding potential penalties and ensuring the reliability of the power supply.

STATCOM are highly effective in mitigating voltage flicker by providing dynamic reactive power compensation, stabilizing voltage, reducing harmonics, and balancing loads. Their rapid response and ability to maintain steady voltage levels make them indispensable in industrial applications, renewable energy integration, and urban power networks. By improving power quality and ensuring voltage stability, STATCOMs contribute significantly to the reliable and efficient operation of electrical systems.