Integrating SIPROTEC Protection Relays via IEC 61850 Station Controller in SIMATIC PCS 7 PowerControl

In SIMATIC PCS 7 PowerControl architectures utilizing an IEC 61850 Station Controller to integrate SIPROTEC 5 protection relays, compiling the exported SCL source code in STEP 7 generates driver communication blocks but does not automatically construct CFC charts. Engineers must manually create a CFC chart for each electrical feeder or circuit breaker bay, instantiating the generated driver block (such as SG_Feeder from the Station Controller library) to handle raw communication and interconnecting it with the technological block (such as PC_Feeder from the PCS 7 PowerControl library) to provide APL faceplates, interlocking, and switching commands.

PCS 7 PowerControl and IEC 61850 Station Controller Architecture

In modern industrial process automation, integrating medium-voltage and high-voltage electrical distribution into the DCS is standardized through SIMATIC PCS 7 PowerControl. Protection relays—such as Siemens SIPROTEC 4 and SIPROTEC 5—communicate over Ethernet using the international standard IEC 61850 (Manufacturing Message Specification - MMS and GOOSE).

To interface IEC 61850 devices with a PCS 7 S7-400 or CPU 410 controller, Siemens deploys the Station Controller:
- An industrial communication gateway or embedded software driver that maps complex IEC 61850 data objects (Logical Nodes, such as CSWI for switch control, XCBR for circuit breaker status, and MMXU for electrical measurements) into controller memory structures.
- Compiling the substation engineering configuration generates an SCL source file containing data blocks and driver function blocks structured specifically for the engineered substation topology.

The Role of SCL Generation and Station Controller Driver Blocks

Compiling the generated SCL file in the STEP 7 Sources folder creates compiled blocks in the offline block container:
1. Data Blocks (DB): Serve as the raw memory image for cyclic communication telegrams exchanged between the AS and the Station Controller.
2. Driver Function Blocks (SG_Feeder, SG_DISC): Unpack raw data structures from the DBs, evaluate communication health, extract breaker positions, and format measurement integers into engineering units.
3. Manual CFC Step Required: The SCL compiler does NOT create CFC charts automatically. The engineering team must instantiate these blocks into the project's Plant Hierarchy.

CFC Engineering Workflow: Pairing SG_Feeder and PC_Feeder

For each physical circuit breaker bay or feeder, engineers implement a two-tier block structure in CFC:

Insert Driver Block (SG_Feeder):
- Place SG_Feeder on Sheet 1 of the feeder CFC chart.
- Assign the appropriate hardware communication DB address generated during SCL compilation.
Insert Technological Block (PC_Feeder):
- Place PC_Feeder (from the PCS 7 PowerControl Library) on Sheet 2.
- PC_Feeder provides the standardized Advanced Process Library (APL) operator interface, command authorization, synchro-check verification, and trip alarming.
Interconnect Driver and Technological Blocks:
- Wire status feedback: Connect SG_Feeder.PosBreaker to PC_Feeder.PosBreaker.
- Wire electrical measurements: Connect current, voltage, and power outputs from SG_Feeder to PC_Feeder.Current, PC_Feeder.Voltage, etc.
- Wire command outputs: Connect switching commands from PC_Feeder.CmdOpen and PC_Feeder.CmdClose to the command inputs of SG_Feeder.
Compile OS: Compiling the OS automatically generates the PowerControl block icons and multi-tab electrical faceplates.

Signal Mapping and Communication Interface Table

The following table details standard block interconnections between Station Controller drivers and PowerControl blocks:

Signal RoleDriver Block (SG_Feeder) PinTechnological Block (PC_Feeder) PinDirectionDescriptionBreaker PositionPosBreakerPosBreakerDriver -> Tech2-bit state: Open, Closed, Intermediate, FaultDisconnector PositionPosDisconnPosDisconnDriver -> TechPosition of upstream isolating disconnectorPhase Current (L1, L2, L3)AmpL1, AmpL2, AmpL3CurrentL1, CurrentL2, CurrentL3Driver -> TechReal-time feeder current measurement in AmperesBusbar VoltageVoltL1L2VoltageDriver -> TechReal-time voltage measurement in kVOpen CommandCmdOpenCmdOpenTech -> DriverTrip/Open circuit breaker pulseClose CommandCmdCloseCmdCloseTech -> DriverClose circuit breaker command pulseCommunication HealthComErrCSFDriver -> TechTriggers Control System Fault on MMS comm loss

Note: In safety-critical electrical distribution, ensure breaker trip circuits utilize hardwired trips alongside IEC 61850 commands.

Verification

Verify SIPROTEC integration and PowerControl faceplate operation:
1. In CFC test mode, confirm that SG_Feeder.ComErr reads False, indicating active IEC 61850 MMS polling.
2. Manually rack in and close the circuit breaker at the physical switchgear; confirm that PC_Feeder.PosBreaker updates immediately to 'Closed' (state 16#02).
3. In WinCC Runtime, open the electrical overview screen; confirm that the feeder block icon animates to closed (red symbol).
4. Click the block icon to launch the @PG_PC_Feeder_Standard.pdl faceplate; confirm real-time currents and active power render accurately.
5. Execute a supervised open command from the faceplate; verify that the relay operates and opens the breaker cleanly.

Limitations and Operational Precautions

Essential substation automation precautions:
- Fast trip signals (such as arc flash protection or differential trips) must execute via hardwired copper or IEC 61850 GOOSE messaging; do not rely on cyclic MMS polling for instantaneous protection tripping.
- Electrical switching operations from the DCS must adhere to strict interlocking (e.g. disconnector open before earthing switch close); enforce interlocking in both the SIPROTEC relay logic and PC_Feeder CFC interlocks.
- Ensure time synchronization between the PCS 7 system and SIPROTEC relays is locked to GPS or IRIG-B (or IEEE 1588 PTP) for sub-millisecond sequence-of-events analysis.

Engineer FAQ

Can I automatically generate CFC charts for 100 feeders?

Yes. By creating a Control Module Type (CMT) that contains the SG_Feeder and PC_Feeder blocks, you can use the Advanced Engineering System (AdvES) or Plant Automation Accelerator (PAA) to generate all feeder charts from an I/O list automatically.

What is the difference between Station Controller and DBA?

The Station Controller integrates IEC 61850 into the AS controller via CFC blocks. The alternative DBA (Direct Block Attachment) architecture routes IEC 61850 data directly from relays to WinCC OS without controller intervention.