Customer:
AC “Ukrtransgas” National Joint-Stock company (JSC) ”Naftogas of Ukraine”

Implementation:
Gas main compressor stations (CS) – CS “Hust”, CS “Ananiev”, CS “Orlovka” Gas Pipeline Division(GPD) “Prikarpattransgas” AC “Ukrtransgas” National Joint-Stock company (JSC) ”Naftogas of Ukraine”.

Functions:
            - automatic check of GCU operation ability;  
            - automatic (according to specified algorithms) and remote (at the shift engineer command) control of process equipment;
            - GCU protection in all operation modes including blower antisurge protection;
            - change of low-pressure turbine (LPT) rotor speed at the command of shift engineer or industrial control system of compressor department (ICS CD);
            - regulation of LPT rotor speed according to specification;
            - regulation of blower working point remoteness from surge area (antisurge regulation);
            - automatic indication, display and audible warning of process parameters runaway from set values;
            - registration and storing  retrospective information of process parameters,  equipment state and shift engineer actions;
            - generating, storing and printing  reports;
            - testing and autodiagnostics of ACS GCU  soft- and hardware;
            - control of transducers data consistency according to measurements results;
            - input, output analogue and discrete chains integrity control;
            - PLC modules operability and digital communication channels control;
            - supply units  consistency  control.

Simplified structure of ACS GCU

Technical solutions:
"SAS-GPA" is based on PLC RX7i, Rx3i, 90-70, VersaMax produced by GE Fanuc Automation. Soft- and hardware reliability is provided by:
            - reservation of LPT and HPT rotor rotation measuring channels;
            - reservation of supply units;
            - united reserved control board for units and adjacent systems of CD;
            - reservation and diagnostics of digital communication channels between control board and control system and transferring critical commands by physical circuits;
            - embedded selfdiagnostic aids and automatic control of input-output analogue and discrete circuits integrity .

Process equipment secure stop is provided by emergency stop unit functionally independent from control system with stand-alone protection channels at LPT limit rotor speed overrun. This unit provides main PLC operational integrity control and safe GCU stop displaying information about main parameters and stop valve position in case of main PLC failure.

“SAS-GPA” hardware provides signals reception from:             - pulse transmitters (0…20) kHz – 8;             - thermal electric transducers – 49;             - resistive temperature transducers – 40;             - transmitters with normalized signal (4-20) mA, (-10...+10) V, (0…+10) V – 48;             - discrete =24 V – 128.
“SAS-GPA”hardware provides control signals output:             - normalized current signals (4-20) mA, (-10...+10) V – 10;             - discrete – 96. Value of main reduced error of data-measuring and control channels (regardless of transmitters and connection lines errors):             - from pulse transmitters (0…20) kHz – 0,15%;             - from transmitters with normalized signal (4-20) mA, (-10...+10) V, (0…+10) V – 0,1%;             - from resistive temperature and thermal electric transducers – 0,2%;             - normalized current control signals (4-20) mA, (-10...+10) V – 0,1%.
"SAS-GPA" has following operation speed parameters:             - scanning period of transducers used in control algorithms (except thermal electric transducers and resistive temperature transducers) – not more than 0,03 sec;             - scanning period of transducers and alarm devices used in logic control and protection algorithms – not more than 0,1 sec;             - period of control signals generation at control channels – not more than 0,03 sec;             - period of control signals generation at control and protection channels – not more than 0,1 ñ;             - execution time for process parameters control modules – not more than 0,02 ñ;             - execution time for control and protection modules– not more than 0,02 ñ;             - period of data update at displays – not more than 0,5 ñ;             - waiting time for frame – not more than 0,5 ñ.