Reactive energy – what is it and how to solve the problem of its consumption

Reactive energy is energy that is necessary to maintain the functioning of power systems but is not converted into useful work, such as mechanical or thermal energy. Reactive power (Q) is the part of electrical power that circulates between the energy source and the receiver without performing useful work. The unit of reactive power is var - Volt-Ampere Reactive.

We distinguish between inductive and capacitive reactive power, depending on the receiving device. Reactive power causes additional load on the power grid, leading to fees aimed at encouraging users to reduce its amount. It affects the capacity of the distribution network and can have negative effects, such as causing failures and overloads. Effective management of reactive energy is a solution that allows for the reduction of additional fees and improves voltage stability in the electrical system.

The coefficient used by operators to calculate the consumption of inductive reactive energy is tgφ. Its level in most cases cannot exceed the value of 0.4 (in areas with infrastructure in worse technical condition, this coefficient is even more restrictive). This means that the consumption of more than 40 kvarh of reactive energy for every 100 kWh of consumed active energy results in an additional fee.

Reactive power is the result of the presence of reactive elements in electrical circuits:

• Inductive reactive power (L) is generated by devices with inductive elements that store energy in a magnetic field. Examples include induction motors, transformers, transmission lines, lighting installations, induction furnaces, and chokes. This type of reactive power causes the current to lag behind the voltage in the phase.
• Capacitive reactive power (C) is generated by devices with capacitive elements that store energy in an electric field. Examples include computers, welders, inverters, live cables, UPSs, and damaged capacitor banks. This type of reactive power causes the current to lead ahead of the voltage in the phase.

The most common method of managing reactive power is reactive power compensation. This involves using devices that can neutralize excess reactive power, such as:

• Capacitors – used to compensate for inductive reactive power.
• Chokes – used for capacitive reactive power compensation.

A very important issue is the appropriate selection of power and individual stages of the reactive power compensation system to avoid undercompensation or overcompensation. It is advisable to perform appropriate measurements.

Modern electrical devices often have built-in reactive power management systems, which allow for more efficient use of energy. Investing in such devices can significantly reduce the amount of reactive power generated. You can also optimize the operation of inductive and capacitive devices. For example, synchronizing the operation of large electric motors can minimize the generated reactive power.

Another solution is advanced energy monitoring and control systems, which can help identify sources of reactive power and optimize their operation. Such systems automatically control compensation devices in real-time. In the case of dynamic changes in reactive power, an advanced active SVG compensator based on thyristors may also be considered.

What Are the Benefits of Reducing Reactive Power?

• Financial savings: reducing reactive power can significantly lower electricity bills, as many energy tariffs include additional charges for excess reactive power drawn from the grid.
• Increased energy efficiency: effective reactive power management increases the overall energy efficiency of the plant, leading to reduced operating costs.
• Reduced risk of network overloads: reducing reactive power decreases the load on the power grid, which can prevent overloads and failures.
• Improved electrical system stability: effective reactive power management improves voltage stability in the electrical system, which is crucial for the proper operation of equipment.
• Increased equipment life: optimizing reactive power reduces the risk of overheating and damage to electrical equipment.

Reactive energy is an important, though often overlooked, element of energy efficiency management. Effective management of reactive power, through compensation, the use of modern devices, and process optimization, can bring significant financial and operational benefits. If a company incurs costs of at least EUR 100 net per month for the consumption of inductive or capacitive reactive energy beyond the contract and these are continuous charges, then reducing its consumption will be a good solution for the company. Usually, undertaking such action results in immediate savings and is characterized by a very short payback period of even less than half a year.

Thinking about the energy efficiency of a company begins with a look at internal processes, measurements, and the reduction of unnecessary energy drawn from the network.