EASY COMMISSIONING GUIDE – FRONIUS PV-SYSTEM CONTROLLER
Reading this document does not substitute for user’s reference to CIRCUTOR CDP-DUO user-guide.
1.1 Scope
Using Fronius grid-tie inverters in remote energy distribution systems that are powered by fossil-fuel powered Gensets require an appropriate/optimal control to maintain stable
grid. This is achieved by maintaining a minimum load level at the Genset, in order to always have enough spinning reserve in the system, and to also attain good power
quality. Typically, such a minimum load level is about 30% of the Gensets nominal power, to avoid an increase in excessive wear-and-tear of the Genset components. The
associated control algorithm is implemented in the Fronius PV System Controller. The power analyzer measures the load to calculate the maximum power target values for
PV-inverters in order to reduce the load on the Genset to a minimum acceptable level, but not below the desired/pre-defined minimum.
1.2 Overview Fronius PV-System Controller
/ Digital Inputs
/ Terminals for CTs
/ Relais Outputs
/ Terminals for communication to inverter (RS-485)
/ Terminals for voltage measurement
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1.2.1 Current Transducers (CTs)
The CTs for Fronius PV System Controllers are customised transducers with a secondary current of 250mA. This customisation is considered to achieve highest accuracy
for measurement purposes.
Standard 5A/1A CTs cannot be used in the standard setup.
CTs are available for the following maximum amperage:
/ MC-3 250A/3-phase (43,0010,0407)
/ MC-1/55 500A/1000A/1500A/1-phase (43,0010,0323)
/ MC-1/80 1000A/1500A/2000A/1-phase (43,0010,0322)
Do note that the amperage of the CT’s must be able to withstand the maximum amperage of the applied diesel generators.
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Use of standard CT’s
The use of Standard CT’s is possible by using a special external measurement extension that is not sourced via Fronius. In that case any standard 1A/5A CTs – even split
core can be used. Do note that this setup might slightly increase response times for communication signal delay reasons.
/ Alternative measurement extension: CVM MINI-ITF-RS485-C2 (Code: M52021)
/ Current transducers: Any standard 1A/5A CTs will do
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Terminals
RS-485
D+
D-
GND
1.2.2 Communication
The following communication channels are provided by the Fronius PV System Controller:
/ R1: Ethernet Modbus TCP (CDP is Server) – optional, see Circutor manual for register specification and details
/ R2 (pins 1-5): RS-422, RS-485, RS-232 Modbus RTU (CDP is Master) – mandatory, to exclusively connect to the Fronius Datamanager 2.0
/ R3 (pins 5-7): RS-485 only Only used for optional Circutor measurement extension (CVM Mini)
(Channel R2)
(FRONIUS MODBUS)
1
2
3
4
5
/
2-wire MODBUS RTU (twisted pair) for connection to Fronius Datamanager 2.0.
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1.3 How can minimum Genset loading be achieved?
/ Place the Fronius PV System Controller along the path of consumption.
/ Link Fronius PV System Controller for MODBUS RTU communication to the Fronius Datamanager 2.0.
/ The feed-in limit can be changed and the range can vary from -999 to 100% of the inverter’s nominal power.
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1.3.1 PV-Genset functional description
The control loop of Fronius PV System Controllers is based on the fast measurement of loads with a full scale power analyzer to realize a consumption based dynamic
curtailment of PV inverter power. The point of measurement has to be a pure path of consumption excluding the generation.
Furthermore the Fronius PV inverters can contribute to an improved power factor in the system by providing a part of the required reactive power.
The PV System Controller determines the setpoints within the range of a power factor (PF = ±0.8).
1.3.2 Compatibility with Fronius inverters
The Fronius PV System Controller can principally be used with all Fronius inverters that allow dynamic active power curtailment.
Nevertheless the desired product for three-phase inverters will be Fronius SYMO and ECO inverters.
/ Fronius Symo with Datamanager 2.0 and later
/ Fronius Eco with Datamanager 2.0 and later
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Terminals
RS-
485
D+
D-
GND
Terminals
RS-
485
D+
D-
-
1.4 Easy commissioning Fronius PV System Controller and Fronius Datamanager 2.0
1
2
3
4
5
(FRONIUS MODBUS)
Description
Modbus Data +
Modbus Data -
Signal GND always connect)
Fronius PV System Controller
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Fronius Datamanager 2.0
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