Static reactive power controller STELCOM®

Static reactive power controller for photovoltaic power plants and other diffuse sources with an output above 100 kW


  • A fixed value of the specified power factor cos φ
  • The power factor as a function of cos φ = f (P)
  • The specified value of reactive power (incoming / outgoing) within the operating diagram machine
  • Voltage at the delivery point or node in a pilot distribution system (DS)
  • The active element of intelligent networks (Smart Grids)


  • The device is dimensioned according STELCOM power transformer to connect the source into the grid

Power line

  • Standard is produced in power for transformers 400, 630, 800, 1000,1250 and 1600 kVA


  • Communication with the control system of the distribution system according to IEC 870-5-104, IEC 61850 or other operator requirements

The physical problem of mass deployment of diffuse sources

Few people realize the physical problem of mass deployment of multiple sources of electrical energy into the grid. Distribution system with the regulation was originally designed for traditional power distribution from defined sources to appliances. In the case of diffuse sources of electricity and especially practical impossibility affect production time, problems arise with voltage regulation in distribution networks (DN). Distribution system as such, it is necessary to reshape the future of so-called Smart Grids (intelligent network), which itself handles sparse production, accumulation and consumption of electrical energy. The future of these networks is still far away, but the problem with voltage regulation in DN is sometimes necessary to deal with today. One option is to use modern power electronic devices - STELCOM, which can be considered one of the first performance features of future Smart Grids.

The principle of electronic compensator reactive power

Compensator is current source, supplying a network of such size reactive current to be achieved the desired power factor. Current generation is in principle ensured control voltage source connected across the inductance of the network. Default is three-phase compensator. If necessary it can be modified to single phase.


Fig. 2: Simplified single-line diagram of the compensator


Fig. 3: Vector diagram of the capacitive current mode


Fig. 4: Vector diagram of inductive current mode

Vector diagrams in Figures based on the replacement scheme will help to explain the principle function of the compensator when the reactive power control by changing the amplitude of voltage compensator UComp. If this voltage is higher than the voltage, occurs on the XR reactance voltage drop with the same phase as the voltage compensator and flows into the network capacitive current compensator behaves like a capacitor. When the compensator voltage lower than the voltage, the reactance loss in the opposite direction and current flow direction is reversed, that is inductive in nature.

How to dimensioning of the compensator?

Proper sizing of any device is always important. This is done so that the system worked perfectly and also to fulfill the economic requirements, Thus the lowest possible price. Nevertheless, it is possible for each type of controller STELCOM reactive power production in many state performance in this more appropriate to state the product range relative to the power transformer, through which PVP Is a connected to the network HV. Power series distribution transformers Is a standardized and therefore these transformers also compiled a number of manufacturing facilities STELCOM. 

Development of product line

Assembly production line equipment STELCOM a purely practical reason. Designers need not difficult to count the required reactive power and try to optimize price, sometimes unnecessary risks, not have the power reserve. Simply select the product line according to the performance distribution (connection) and the current transformer and switchgear project the size and location of connection to the substation STELCOM PV power plants. It is important that STELCOM was placed as close to a distribution transformer due to the lower sizing wires to PV power plants and reduce line losses.

STELCOM product line designed to control the reactive power of photovoltaic power plants connected to the HV network.

Parameter/Model 181- t400 285- t630 362- t800 452- t1000 565- t1250 725- t1600
Power transformer to the distribution network [kVA] 400 630 800 1000 1250 1600
Voltage [V] 3x400
Current (at a voltage 3x400 V) [A] 181 285 362 542 565 725
Connectable PV power [kWp] 380 600 760 950 1190 1520
Regulating range [cos φ] 0.95 capacitive to 0.95 inductive
Response rate [ms] Optional parameter (minimum 20 ms)
Dimensions [2200 mm (H) x 800 mm (h) x W] 800 800 1600 1600 2400 2400
Frequency [Hz] 50 (optionally 60)
Communication protocol IEC 60870-5-104 or IEC 61850
Communication connection Ethernet, GSM or RS485 for diagnostics
Maximum losses [W] 5200 7800 10400 12400 15500 20800
Execution Internal (optional external)
The total harmonic current distortion 5 %
Weight [kg] 350 460 690 780 1030 1320


Additional features electronic compensator

  • Control of cos φ - STELCOM is essentially a power generator with power control the size and direction of current flow first harmonic of capacitive or inductive. Its basic feature is the power factor cos φ control.
  • Harmonic Filtering - Another additional function device STELCOM then more related to the overall requirements of the quality of the mains voltage. If the voltage is distorted by harmonics, then you can use the advanced features STELCOM move to suppress certain harmonics and thus improve the power factor ? real. The device then behaves simultaneously as a parallel active filter, which eliminates the deformation performance of the network.
  • Reduce Flicker - One additional feature is the possibility of equipment STELCOM mitigate flicker in the power network. A sophisticated control system in the monitored network node enables the power of the installation options to mitigate the unpleasant flicker, thus fulfilling the operator DN as one of the conditions of the standard DIN EN 50160
  • Current symmetrization - Last STELCOM additional device features is the ability to ensure the symmetry of current drawn. It can be as large importance of PV power plants, which consist of multiple single-phase inverters. Here it is advisable to use this additional function to ensure the additional current consumption in the symmetric three-phase system.
  • Voltage Stability - It is obvious that all the previous features in the total mean improvement in the quality of the mains voltage.