Monday, January 14, 2013

IEC 61850 Extensions for Control Systems in Thermal Power Plant

Part 90-13 of the IEC 61850 series is under way. The draft document specifies the additional common data classes, logical nodes and data objects required for the use of IEC 61850 in Thermal Power Plants.

Some years ago the power plant control systems started to connect to the power plant internal power delivery system for the power loads inside a power plant.

In a whitepaper dated 2007 Joerg Orth, ABB AG, Mannheim, published an interesting white paper on the connection between the two systems based on IEC 61850: “Future power plant control - Integrating process & substation automation into one system”

“Today’s power plants are highly automated. All subsystems of large thermal power plants can be controlled from a central control room. One subsystems area is the electrical auxiliaries for the unit transformer, the grid connection, excitation, synchronization, generator/unit protection, auxiliary transformers, HV-, MV- and LV-switchgear. In the past, these electrical devices were all hardwired to the DCS and I/Os. To this day, horizontal communication between electrical devices is still hardwired. In the last decade, serial communication protocols were introduced. Unfortunately, standardization of these protocols went in different directions. Today there are several standards on the market. … The future is talking IEC 61850 providing solutions for seamless integration concepts for new and refurbishment projects.”

These days the development goes a step further: IEC 61850 extensions for power plant internal (!) control functions. This is a new approach for internal control functions, because it has an impact on the power plant control system – not only on the internal and external substations.

The current draft of IEC 61850-90-13 defines, for example the following specific Logical Nodes for Thermal Power Plants:

EJCL Power plant joint control function.
ESEQ Start / stop sequencer.
ESPD Speed monitoring.
EGTU Gas turbine production unit.
EUNT Thermal unit operating mode.
ESTU Steam turbine production unit.
For some data objects see below
EBCL Boiler control function.
MENV Environmental data
MGAS Gas-flow measurement.
MOIL Oil-flow measurement.
MSTE Steam-flow measurement.
MEXH Exhaust Gas Mass Flow.

Draft settings of the LN ESTU (Steam turbine production unit):

Turbine type (steam, gas, oil)
Turbine rated speed [s-1]
Turbine moment of inertia J [kgm2]
Maximum transient overspeed [s-1]
Runaway speed [s-1]
Rated power in turbine mode [MW]
Rated flow in turbine mode [kg/s]
High pressure inlet maximum pressure [Pa]
Intermediate pressure inlet maximum pressure [Pa]
Low pressure inlet maximum pressure [Pa]
High pressure control valve rated oil pressure [Pa]
High pressure control valve rated closing time [s]
Intermediate pressure control valve rated oil pressure [Pa]
Intermediate pressure control valve rated closing time [s]
Low pressure control valve rated oil pressure [Pa]
Low pressure control valve rated closing time [s]

As can be seen from this example, IEC 61850 arrived at the modeling and communication of the power plant internal control system level. More to come. The draft has been written by the IEC TC 57 WG 18. It will be discussed at its next meeting in March 2013 in Nice (France). WG 18 has already published the LNs for Hydro Power Plants (IEC 61850-7-410 Ed2).

ABB Whitepaper on IEC 61850 in Power Plants written in 2007 by Joerg Orth [pdf]

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