Reactive Power

Reactive power is the electricity that flows through the grid to create magnetic fields in equipment such as cables, motors and transformers, but does not deliver usable energy itself.

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What is reactive power in the electricity grid?

To understand reactive power, it helps to look at how alternating current (AC) works.

In the Netherlands, we use AC, where the current direction changes 50 times per second (50 Hz). Both voltage (Volt) and current (Ampere) follow a sinusoidal wave.

In an ideal situation, voltage and current are perfectly aligned—in phase. All supplied power is then converted into usable energy.

In practice, many installations contain:

• inductive components (coils), such as motors and transformers
• capacitive components, such as electronics or compensation systems

These components create a phase shift between voltage and current:

• with inductive load, current lags behind voltage
• with capacitive load, current leads voltage

This phase shift results in reactive power.

Reduced usable power

The larger the phase shift (and thus the reactive power), the less efficiently the grid is used:

• more current is required for the same amount of useful energy
• cables and transformers reach their limits faster
• voltage quality can deteriorate
• additional losses occur in the grid

That is why improving the power factor—reducing or compensating reactive power—is essential.

Reactive power also affects voltage

Maintaining a consistent voltage (e.g., 230 V or 10,000 V) in the electricity grid is vital, as equipment is designed to operate within specific voltage ranges. Significant deviations—whether too high or too low—can lead to:​

• Malfunctioning equipment​
• Increased wear and tear​
• In severe cases: failures or damage​

Reactive power contributes to these voltage problems because it affects the total current flowing through the grid, influencing voltage levels and stability.

Impact on voltage drop and rise

When electricity flows through a cable, a voltage drop always occurs. This depends on:

1. the amount of current
2. the cable properties (resistance and inductance)

Reactive power increases the current without adding useful power. This amplifies voltage deviations:

• inductive reactive power (e.g. from motors) often causes voltage drops
• capacitive reactive power (e.g. from inverters or long cables) can cause voltage rise

In a well-balanced grid, this remains manageable. But in congested areas, excessive reactive power can lead to significant voltage issues.

An Example

In a neighbourhood with a lot of solar generation inverters may produce capacitive reactive power. Local demand is low. As a result:

• high (reactive) currents flow to the medium-voltage grid
• voltage at transformers increases
• other users in the area may experience voltage problems

Conversely, a factory with high inductive load during peak demand can cause voltage to drop too far, increasing the risk of failures.

Reducing reactive power

Large-scale energy users can actively contribute to managing reactive power. With the right settings and smart control, it’s possible to:

• Reduce reactive power (generate less of it)
• Compensate for it (supply negative reactive power when the grid demands positive, or vice versa)

Do you have:

• large electric motors or pumps?
• industrial processes with high inductive load?
• heat pumps, compressors or variable loads?
• controllable inverters (e.g. in BESS, solar or wind parks)?

Then you likely have flexible capacity that can help manage reactive power on the grid.

Interested in participating? Visit this page.

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