SMA SUNNY TRIPOWER, SUNNY HIGHPOWER Technical Information
Technical Information
Integrated Plant Control and
QonDemand 24/7
SUNNYTRIPOWER / SUNNY HIGHPOWER
1 Function Availability
Reactive power is necessary for the stability of the utility grid. With the functions "IntegratedPlantControl" and
"QonDemand 24/7", SMA SunnyTripower inverters can feed reactive power into the grid during operation and
overnight. This document provides basic information on reactive power and how to configure the inverter in order to
provide reactive power in compliance with standards and demand.
The following table provides an overview of the device types and firmware versions for which the various functions are
available. Please note that the complete firmware version of the inverter can only be displayed via a communication
product.
SMA inverter
(Device type)
STP 50-40/
STP 50-US-40/
STP 50-JP-40
STP 33-US-41/
STP 50-US-41/
STP 62-US-41
STP 60-10/
STP 60-US-10
STP 60-JP-10 from firmware version 1.80 from firmware version 1.80 not available
SHP 75-10 from firmware version 1.91 from firmware version 1.91 not available
SHP 75-JP-10 from firmware version 2.0 from firmware version 2.0 not available
STP15000TL-10/
STP17000TL-10
Reactive power provision 0
overexcited
0
underexcited
from firmware version
1.03.04
from firmware version
1.09.03.R
from firmware version 1.60 from firmware version 1.60 not available
from firmware version
2.60.02
to
QonDemand 24/7 IntegratedPlantControl
from firmware version
1.03.04
from firmware version
1.09.03.R
from firmware version
2.60.02
from firmware version
1.03.04
from firmware version
1.09.03.R
from firmware version
2.62.04
STP15000TLEE-10/
STP20000TLEE-10
STP20000TL-30/
STP25000TL-30
STP 12000TL-US-10/
STP15000TL-US-10/
STP20000TL-US-10/
STP24000TL-US-10/
STP30000TL-US-10
from firmware version
2.61.06
from firmware version
2.80.04
from firmware version
2.80.00
from firmware version
2.61.06
from firmware version
2.82.03
from firmware version
2.80.00
IPC-QoD24-7-STP-TI-en-17 | Version 1.7ENGLISH
from firmware version
2.63.03
from firmware version
2.81.03
from firmware version
2.80.00
2 Definition of Active Power, Reactive Power and Apparent Power
SMA Solar Technology AG
2 Definition of Active Power, Reactive Power and Apparent Power
Electrical power is the product of current and voltage. While current and voltage have stable values with direct current,
the strength and the direction of both current flow and voltage change regularly in alternating current. In the utility grid,
current and voltage have a sinusoidal progression, meaning that their product, electrical power, is also sinusoidal. In
DC systems, the sign of the power indicates the direction in which the electrical energy, in the form of active power, is
transported. In general, this also applies in an AC circuit. However, the power may not always be constantly positive
or constantly negative, but rather its sign can fluctuate periodically, causing the power to oscillate back and forth. This
oscillating power does not do any work and is therefore referred to as reactive power. The time delay between the
current and voltage curve - the so-called phase shift - is a value which is easy to measure and characteristic of the
relationship between active power and reactive power at the point under consideration in the electric circuit.
2.1 Active Power P
With no phase shift between the progression of current i(t) and voltage v(t) over time, both always have the same sign
and simultaneously reach their maximum and minimum values. The power oscillates between zero and the positive
maximum value. Averaged over time, this results in a positive power value P (unit: W; watt) and only active power P is
generated. This behavior only occurs when ohmic loads are the only loads in the electric circuit. In a real utility grid,
however, the line inductances and capacitances alone result in the active power always being accompanied by a
small amount of reactive power.
Figure 1: Pure active power: current and voltage are in phase
Technical InformationIPC-QoD24-7-STP-TI-en-172
SMA Solar Technology AG
2 Definition of Active Power, Reactive Power and Apparent Power
2.2 Reactive Power Q
With a phase shift phi of 90°, the maximum current occurs precisely when the voltage crosses zero, resulting in the
power oscillating between positive and negative values. The average over time is therefore zero. This is known as pure
reactive power Q (unit: Var, from the French volt-ampère-réactif), which moves "back and forth" in the lines.
Figure 2: Pure reactive power: current and voltage are out of phase by 90°
2.3 Apparent Power S
In real AC circuits, there is a mix of active power and reactive power. This behavior occurs if there are lagging or
leading loads in the utility grid. The shift between current and voltage is denoted by the displacement power factor
cosφ.
Figure 3: In real AC grids, current and voltage are slightly out of phase and reactive power occurs together with active power
Technical Information 3IPC-QoD24-7-STP-TI-en-17
2 Definition of Active Power, Reactive Power and Apparent Power
SMA Solar Technology AG
Calculating Apparent Power
The sum of active power and reactive power is the so-called apparent power S (unit: VA; volt-ampère). It should be
noted that the values are not simply added arithmetically, rather the geometric sum must be calculated: active and
reactive power form the adjacent and opposite sides of a right-angled triangle respectively, the hypotenuse
corresponds to the apparent power. The cosine of the angle between the active power and the apparent power is the
displacement power factor.
Figure 4: Geometric addition of active and reactive power
2.4 Reactive Power Compensation and Control with SunnyTripower
Compensating for Reactive Power Demand with QonDemand24/7
Leading or lagging loads (e.g. cables, transformers) require reactive power. Transporting reactive power from the
power plant to the load places a burden on the utility grid. It is therefore expedient to install a compensation system
that provides reactive power at sites where there are many leading or lagging loads. In order to ensure the stability of
the utility grid, grid operators demand that energy producers participate in reactive power compensation. A PV system
can complement or replace such a compensation system.
Due to their design, large PV farms have a certain demand for reactive power that can be compensated for with
SunnyTripower inverters. At the same time, SunnyTripower inverters can make reactive power available for the utility
grid. Compensation can take place both during and outside of feed-in operation via the "QonDemand24/7"
function. Via this function, the SunnyTripower inverter provides reactive power for the PV farm equipment without
placing an appreciable burden on the utility grid.
Controlling the Q(V) Characteristic Curve with IntegratedPlantControl
The SunnyTripower inverter can provide reactive power to the utility grid with the "IntegratedPlantControl" function.
The grid operator specifies via which process the inverter is to provide reactive power to the utility grid. In many cases,
the grid operator will request control in accordance with a Q(V) characteristic curve.
SMA inverters with "IntegratedPlantControl" are capable of reproducing this Q(V) characteristic curve without
performing any measurement at the grid-connection point. The inverter can automatically compensate for equipment
installed between the inverter and the grid-connection point.
The function "IntegratedPlantControl" is not capable of compensating for irregular or fluctuating reactive power
demands due to, for example, connected machinery, if the machinery is connected between the inverters and the gridconnection point. If the machinery is connected directly at the grid-connection point, it is possible to dynamically
determine the additional reactive power demand of the machines using additional measurement equipment and then
to provide this value as an offset to the Q(V) control.
Technical InformationIPC-QoD24-7-STP-TI-en-174
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