Integrating Electrical Substation Protection via SICAM PAS and IEC 61850 into PCS 7

In SIMATIC PCS 7 V8.2, integrating medium and high-voltage electrical substation protection devices (such as SIPROTEC, Reyrolle, or Argus M relays) via SICAM PAS (Power Automation System) is achieved through two standard architectural pathways. For supervisory monitoring and alarming at the Human-Machine Interface layer, SICAM PAS acts as an OPC DA/UA server communicating directly with the WinCC OS redundant servers over the Terminal Bus. For deterministic, real-time protection interlocking and electrical control at the controller layer, the S7-400 integrates the SIMATIC PCS 7 Power Control Library communicating over Industrial Ethernet via CP 443-1 using IEC 61850 MMS and GOOSE protocols, providing native APL-style electrical faceplates.

Substation Automation System (SAS) Architecture in Industrial Plants

Modern chemical, oil and gas, and mining facilities operate large private electrical distribution networks (medium-voltage switchgear, transformers, generator breakers, and motor control centers). Electrical protection relays—such as SIPROTEC 4 / 5, Reyrolle, and Argus M—monitor currents, voltages, and frequencies to trip breakers under overcurrent, earth fault, or reverse-power conditions.

SICAM PAS (Power Automation System) serves as the specialized Substation Automation gateway. It concentrates heterogeneous electrical protocols (IEC 61850, IEC 60870-5-103, IEC 60870-5-104, and Modbus) from relays across the electrical substation and standardizes the data model. To provide plant operators with a unified control environment, SICAM PAS must interface seamlessly with the central SIMATIC PCS 7 V8.2 Distributed Control System.

Integration Architectures: HMI-Level OPC vs. Controller-Level IEC 61850

When integrating SICAM PAS into PCS 7, engineering requirements dictate one of two distinct methodologies:

HMI-Level Integration via OPC DA / OPC UA (Supervisory Architecture):
- How it works: SICAM PAS hosts an integrated OPC Server. The redundant WinCC OS Servers connect as OPC Clients across the plant Terminal Bus. Tags, alarms, and electrical single-line mimics are managed in WinCC.
- Suitability: Ideal for electrical monitoring, transformer temperature logging, energy metering, and operator breaker switching where sub-second deterministic interlocking with chemical processes is not required.
Controller-Level Integration via SIMATIC PCS 7 Power Control (Deterministic Architecture):
- How it works: The S7-400 controller connects directly to the substation Industrial Ethernet bus via CP 443-1 using the PCS 7 Power Control Library (6ES7658-7...). Communication uses IEC 61850 MMS (Manufacturing Message Specification) for cyclic telemetry and GOOSE (Generic Object Oriented Substation Events) for high-speed interlocking.
- Suitability: Mandatory for fast load shedding, emergency generator synchronization, and automated busbar transfer schemes executing within millisecond deadlines.

Communication Interface and Protocol Comparison Matrix

The following table compares the two integration pathways between SICAM PAS and SIMATIC PCS 7:

| Architectural Parameter | Option A: HMI-Level OPC Integration | Option B: PCS 7 Power Control (IEC 61850) |
|---|---|---|---|
| Communication Gateway | SICAM PAS OPC Server | Direct CP 443-1 to Substation Bus / SICAM PAS |
| Underlying Protocol | OPC DA / OPC UA over TCP/IP | IEC 61850 MMS & GOOSE over Ethernet |
| Connection Level | WinCC OS Server (Terminal Bus) | S7-400 AS Controller (Plant Bus / Substation Bus) |
| Deterministic Speed | 500ms to 1000ms polling latency | < 20ms (GOOSE) / 100ms (MMS) |
| Technological Faceplates| Custom WinCC graphics or OPC tags | Standard APL-Style Power Control Faceplates |
| Software License Required| WinCC OPC Channel License | PCS 7 Power Control AS/OS Engineering & RT |

Step-by-Step Procedure to Integrate SICAM PAS with PCS 7

To implement supervisory substation monitoring using the robust HMI-Level OPC integration architecture:

Configure Electrical Network in SICAM PAS UI:
- In the SICAM PAS Configuration UI, configure the serial and Ethernet communication lines to the Argus M and SIPROTEC relays.
- Map protection variables (breaker positions, voltage, active/reactive power, fault trips) into the SICAM PAS internal tag dictionary.
- Enable the SICAM PAS OPC Server daemon (opcePas.exe) and configure client security permissions.
Configure WinCC OPC Channel on the PCS 7 OS Server:
- Open the master OS Server project in WinCC Explorer.
- In Tag Management, right-click and select Add New Driver -> OPC.
- Under the OPC driver branch, expand OPC Groups and right-click System Parameter.
- Browse the local network or Terminal Bus to locate the SICAM PAS OPC DA Server.
- Test connection credentials; verify that the tag browser displays the hierarchical substation structure (Substation -> Bay -> Relay).
Import Substation Tags and Configure Alarms:
- Select and import the required electrical tags (e.g., Bay01_CB_State, Bay01_Current_L1, Bay01_Trip).
- In WinCC Alarm Logging, map digital trip tags to standard PCS 7 Electrical Alarm Classes with high audit priority.
Build Electrical Single-Line Graphics and Compile OS:
- In Graphics Designer, build electrical single-line diagrams using standard APL breaker symbols or customized objects.
- Connect dynamic color states to breaker status tags (0 = Open/Green, 1 = Closed/Red, 2 = Tripped/Flashing Yellow).
- Generate OS Server Data and download the updated configuration to redundant OS servers and clients.

Verification

Verify substation telemetry and alarming in PCS 7:
1. In WinCC Runtime, open the electrical substation overview graphic; verify that busbar voltages and feeder currents display live values matching physical relay displays.
2. Simulate a test breaker open/close status on an Argus M relay; confirm that the single-line diagram symbol updates within 1 second.
3. In the WinCC Alarm List, confirm that electrical protection trips generate high-priority alarm messages recording timestamps, bay names, and relay trip codes.
4. Disconnect the SICAM PAS network link; confirm that WinCC tags transition cleanly to bad quality code (16#00) without crashing the OS server.

Limitations and Operational Precautions

Fast Electrical Interlocking Prohibition via OPC: Never execute safety-critical electrical interlocking (such as arc-fault tripping or synchrocheck) across OPC; use hardwired I/O or IEC 61850 GOOSE.
Terminal Bus Network Isolation: Isolate the electrical substation network from corporate LANs using an industrial firewall to prevent broadcast storm interference.
Commercial Accuracy Disclaimer: Procurement of the SIMATIC PCS 7 Power Control Library (6ES7658-7...) and SICAM PAS licenses must be verified against authorized Siemens Energy distribution catalogs.

Engineer FAQ

Can PCS 7 communicate directly with IEC 61850 relays without SICAM PAS?

Yes, using the SIMATIC PCS 7 Power Control Library and CP 443-1, an S7-400 can communicate directly with IEC 61850 protection relays.

Why use SICAM PAS if PCS 7 can talk IEC 61850?

SICAM PAS serves as a multi-protocol gateway that integrates older legacy relays (such as serial IEC 60870-5-103 or Modbus) and provides dedicated substation disturbance recording.

Which protocol is used for millisecond electrical tripping?

IEC 61850 GOOSE (Generic Object Oriented Substation Events) provides peer-to-peer layer-2 Ethernet communication executing in under 10 milliseconds.

Does WinCC require a separate license to connect to the SICAM PAS OPC Server?

Connecting via standard WinCC OPC DA client uses the basic WinCC connectivity package, but high-performance integration typically uses the PCS 7 Power Control OS package.