Capacitors for medium voltage

Taking reactive power compensation efficiency to a higher level

Medium and high voltage capacitor banks allow for central compensation of large reactive power levels up to 100MVAr. These capacitors are available in ratings up to 150kV and can be connected at the primary side of the transformer. This means smaller currents need to be compensated for the same amount of reactive power. Capacitors connected to medium voltage operate on the same principles as low voltage capacitors.

Advantages of reactive power compensation on medium voltage

  • Suitable for loads connected directly to medium voltage.
  • Large power applications
  • Higher energy density, therefore requiring less room for the same amount of reactive power compensation.
  • Cost effective for larger compensations.

Application

Capacitors connected to medium voltage are often applied at central reactive power compensation. This is an appropriate solution if large numbers of loads, or dispersed loads, are present at the plant. Furthermore, medium voltage compensation is available for higher reactive power compensation than is the case for low voltage.

HyTEPS delivers customized solutions

Several examples in which HyTEPS can support the design process with customization:

  • High altitudes (1000m above sea level)
  • Salty air (offshore)
  • Extreme temperatures
  • 3 phase (wye or delta) compensation
  • With or without internal fuses
  • Unbalance protection
  • Servicing protocols without loss of production

Each installation is unique. However, all installations share certain properties. HyTEPS has the experience to find these similarities and come up with a cost-effective solution. An all-in-one solution, for example, where all components, capacitors, regulators and security are mounted in a rack or cabinet.

Capacitors with built-in fuses

One of the decisions that needs to be made is whether to use capacitors with or without built-in fuses. The advantage of built-in fuses is the fact that the capacitor bank will continue to function in the event of a small defect. The only cost is an extremely small amount of capacity loss. However, these capacitors are slightly less efficient due to additional losses within the fuses.

Power factor correction controller

A capacitor bank is introduced when reactive power needs to be compensated. However,  reactive power consumption in your installation may change over time. Loads on the grid change continuously. Think of switching large motors on or off, day/night cycles in your production, or - even simpler - an increased load during working hours. To provide the right amount of compensation for every moment of every day, regardless of the circumstances, it is important to apply a power factor correction controller. This controller will engage or disengage additional capacitors. This is also important for the voltage level in the installation. A capacitive grid often has a raised voltage, which might lead to new problems.

Sustainability

HyTEPS works exclusively with market-leading manufacturers, for who product sustainability, as well as financial, technical and ecological sustainability, are of the utmost importance. Examples include self-developed electrolytes, which are non-toxic, biodegradable and maintenance-free. Or, for example, built-in discharge resistors, which ensure a capacitor becomes harmless to (maintenance) personnel after a short duration.

Medium voltage capacitors and other Power Quality phenomena

Unbalance

By continuously measuring unbalanced current, internal failure of the capacitors can be detected on time, at which point the capacitors shut down the installation. This prevents dangerous situations, such as fires or explosions caused by worn out capacitors. Measurement also provides real time insight into the condition of the components. Therefore preventive maintenance can be executed, preventing larger damages.

Harmonic voltages

Capacitors are sensitive to harmonic voltages. Compared to low voltage grids, harmonics are on the medium voltage grid are relatively smaller. There are two methods for further decreasing the effect of harmonic voltages on the capacitors. When only small harmonic voltages are present, the capacitor banks will be “detuned”. This prevents amplification of the harmonics. When a significant amount of voltage harmonics are already present, the capacitors will be tuned to act as a filter. This is also known as a a passive filter and can be engaged for any frequency.

Resonance

Adding capacitance changes the grid impedance. The higher the frequency, the lower the capacitor impedance. Combined with the inductance of other components in the grid, this can lead to resonance within the installation. It is also of importance to account for all modi operandi, such as emergency operations on generators.

Voltage level

In general, the voltage level of an installation rises when a capacitor bank is added. This can lead to unnecessary wear on the capacitors, as well as other parts of the installation. Research prior to installing a capacitor bank, by means of measurement or simulation,  determine the necessary preventive actions to be taken, as well as the appropriate capacitor bank dimensions.

HyTEPS has been an expert in reactive power compensation for over 10 years.

 

HyTEPS offers customized solutions. Thanks to our extensive knowledge of Power Quality phenomena are we able to prevent problems in your complex installation. Reactive power compensation has a direct effect on the efficiency of your installation. It can lower costs, and increase the capacity of your installation. In case of large- or dispersed installations it can be cheaper to compensate the reactive power centrally on the medium voltage.

Ask an Power Quality Expert