How to effectively manage reactive power?

There are two main types of reactive power:

• Inductive reactive power (inductance – L) – generated in devices with inductive components such as motors, transformers, chokes, or induction furnaces. It is characterized by a phase shift where current "lags" behind voltage.
• Capacitive reactive power (capacitance – C) – generated by electronic devices and systems with high electrical capacitance, such as inverters, cables, UPS units, or modern LED lighting. In this case, current "leads" voltage.

An excess of either inductive or capacitive reactive power results in additional charges under the tariffs of distribution system operators and increases transmission losses, and can sometimes lead to grid overload.

Modern plants, where the load profile changes and various devices generating both types of reactive power are used intensively, need tailored solutions to compensate for its excess as efficiently as possible.

The most common mistakes in managing reactive power are:

• overcompensation – incorrect power factor settings of installed capacitor/choke banks can lead to an excess of capacitive/inductive power and additional charges,
• lack of source localization – installing capacitors in one part of the plant while the source of reactive power is located elsewhere,
• lack of automation – manual control of compensation under variable load conditions results in under- or overcompensation,
• failure to modernize the compensation system after plant upgrades, e.g., after adding modern motors, LEDs, inverters,
• lack of measurements – managing reactive power without prior data analysis can lead to costly and ineffective solutions.

In industrial plants where the load varies over time, automatic compensation systems with step or smooth regulation are the most effective. They consist of capacitors, chokes, and controllers with automation that selects compensation power in real time. This allows maintaining tgφ at the level required by the DSO, without overcompensation.

tgφ is a coefficient used by grid operators to settle reactive power consumption. Its level usually must not exceed 0.4 (sometimes it is even more restrictive) – this means that consuming more than 40 kvarh of reactive power per 100 kWh of active power results in an additional charge from the operator.

There are situations where traditional solutions for reactive power compensation, such as switching individual capacitor/choke stages, may be insufficient. In such cases, active compensators (SVG – Static Var Generator) are used – electronic systems that dynamically compensate both inductive and capacitive power, and often higher harmonics as well.

In large-scale plants or where large individual sources of reactive power are present (e.g., motors over 200 kW), local compensation – directly at the receiver – is worth considering. This reduces reactive power flow in supply lines, limits transmission losses, and locally improves voltage levels.

Effective reactive power management requires reliable data. To obtain it, the following are used:

• network parameter analyzers – enable tracking active power, reactive power, harmonics, surges, voltage asymmetry, and other power quality parameters in real time,
• disturbance recorders and long-term data logging – useful for analyzing load variability and assessing the effectiveness or selection of compensation,
• SCADA or EMS systems – allow full visualization, analysis of historical data, and remote control of compensation devices.

Such solutions allow for a quick response in case of parameter exceedance and maintaining high energy efficiency without the need for constant manual control.

Failure to act on reactive power management results in more than just higher electricity bills. It involves a range of risks that can negatively impact the operation of the entire plant:

• additional costs – charges for excessive reactive power consumption, often amounting to several or even tens of thousands of zlotys per month,
• risk of overloading the internal grid – especially in older installations,
• voltage and power quality issues – leading to flickering lights, inverter failures, and malfunctions of other sensitive power electronic devices,
• shortened equipment lifespan – overheating of transformers and lines, as well as excessive operation of cooling equipment,
• difficulties in meeting ISO 50001 standards – regarding monitoring and improving energy efficiency.

In extreme cases, excess reactive power can lead to production downtime or costly upgrades of the internal power network.

In a modern approach to energy efficiency, managing reactive power is not a one-time action but part of a systemic strategy. It should be included during energy audits and installation inspections, when planning investments in new equipment, or as part of the company’s energy policy aligned with ESG and decarbonization strategies.

Integrating reactive power management systems with comprehensive EMS (Energy Management System) platforms enables ongoing monitoring and reporting of efficiency indicators, resulting in long-term savings and improved plant reliability. Reactive power is not only a matter of fees but also reliability, power quality, and equipment durability. Lack of action can have financial and operational consequences. Therefore, reactive power management should be based on accurate measurements, properly selected technologies, and continuous monitoring.