Areva MiCOM P441, Technical Manual

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Relay Description P44x/EN HW/E33
MiCOM P441/P442 & P444 Page 7/44
1.2 Software overview
The software for the relay can be conceptually split into four elements: the real-time
operating system, the system services software, the platform software and the protection
and control software. These four elements are not distinguishable to the user, and are all
processed by the same processor board. The distinction between the four parts of the
software is made purely for the purpose of explanation here:
1.2.1 Real-time operating system
The real time operating system is used to provide a framework for the different parts of the
relay’s software to operate within. To this end the software is split into tasks. The real-time
operating system is responsible for scheduling the processing of these tasks such that they
are carried out in the time available and in the desired order of priority.
The operating system is also responsible for the exchange of information between tasks, in
the form of messages.
1.2.2 System services software
The system services software provides the low-level control of the relay hardware. For
example, the system services software controls the boot of the relay’s software from the non-
volatile flash EPROM memory at power-on, and provides driver software for the user
interface via the LCD and keypad, and via the serial communication ports. The system
services software provides an interface layer between the control of the relay’s hardware and
the rest of the relay software.
1.2.3 Platform software
The platform software deals with the management of the relay settings, the user interfaces
and logging of event, alarm, fault and maintenance records. All of the relay settings are
stored in a database within the relay which provides direct compatibility with Courier
communications. For all other interfaces (i.e. the front panel keypad and LCD interface,
Modbus and IEC60870-5-103) the platform software converts the information from the
database into the format required. The platform software notifies the protection & control
software of all setting changes and logs data as specified by the protection & control
software.
1.2.4 Protection & control software
The protection and control software performs the calculations for all of the protection
algorithms of the relay. This includes digital signal processing such as Fourier filtering and
ancillary tasks such as the measurements. The protection & control software interfaces with
the platform software for settings changes and logging of records, and with the system
services software for acquisition of sample data and access to output relays and digital opto-
isolated inputs.
1.2.5 Disturbance Recorder
The disturbance recorder software is passed the sampled analogue values and logic signals
from the protection and control software. This software compresses the data to allow a
greater number of records to be stored. The platform software interfaces to the disturbance
recorder to allow extraction of the stored records.