Te Mihi Commissioning Te Mihi Power Station 01 May 2014
Contents 2 Part 1: Overview and Features Station Overview Control and Features Built-in Test Facilities Lessons Learnt Part 2: Testing and Mathematical Modelling Governor Testing Frequency Injection Excitation Testing PSS Part 3: Market Unit Vs Station Risk SPD Modelling
Part 1 THI Station Overview
Name Plate Data 4 Steam Turbine Generator» Make Toshiba» KVA 108,706» Phase 3» Poles 2» Hz 50» Volts 11,800» Amperes 5,319» Power Factor 0.85» Insulation Class F
Name Plate Data 5 Steam Turbine» Make Toshiba» Rated Output 83,507 kw» Maximum Output 91,857 kw» Rated Speed 3000 rpm» IP Steam Pressure 5.20 bara» IP Steam Temperature 153 o C» LP Steam Pressure 1.14 bara» LP Steam Temperature 103 o C» Exhaust Pressure 65 mbar
Steam Turbine Generator Overview 6
D-EHC Controller System Configuration 7
D-AVR Controller System Configuration 8
Operating & Control Features 9 Turbine» Governor Control» Automatic Load Regulation (ALR)» Load Limiter (LL)» Load Limiter Follow-up Load Regulation» Governor Follow-up Load Regulation» Inlet Pressure Regulation» Initial Pressure Control protection function» Vacuum Unloader protection function Generator» Voltage Control» Power Factor Control» MVAR Control
Governor Follow-up Load Regulation 10
Load Limiter Follow-up Load Regulation 11
EHC & AVR Test Facilities 12 EHC» Built-in Frequency Injection Function» Built-in Frequency Step Function» Transient Recording Capability AVR» Built-in Voltage Step Function» Built-in UEL, OQL, VPFL & OCL functions» Transient Recording Capability
Frequency Injection 13
Frequency Injection Faceplate 14
Transient Recorder 15
AVR Test Facility 16
Transient Recorder 17 Toshiba is capable of recording up to 5 groups of transient parameters Each group can record 8 Analog data and 32 digital Data Records faults automatically in a cyclic manner Recording can be manually triggered Currently set-up at 2 millisecond scan time and a record time of 19 seconds.
% Valve Position Load (MW) Factors Affecting Unit Performance 18 110 100 90 80 70 60 50 40 30 20 10 0 Load vs Valve Position 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 110 Flow Demand / Governor Setting Position (Design) Load (Design) Change in Speed Flow Demand Valve Position
Factors Affecting Unit Performance Steam and Ambient condition factors.» NCG in Steam» Steam Flow» Steam Pressure» Power Factors» SGW Temperature» Power Factor» Ambient Wetbulb Temperature 19
Good Practices 20 Good safety practices - No significant safety incidents» Constant safety vigilance pays off» Knowledge and experience of workers are vital SO s site visibility» Better coordination equals quick responses and better outcomes Open line communication to SO» Good business relationships makes good business outcomes» Things gets resolved in a more timely manner
Good Practices 21 OEM s professionalism and commitment to help» Site engineers in-depth knowledge of their equipment» Willingness to make system modifications to satisfy the Contract requirements Toshiba s built-in test functions» Made current and future testing alot easier
Areas of Improvement 22 PRESENTATION TITLE Safety procedures and documentations» Contactors should have a well-tested safety procedure and documentations for Transpower-Project interface works No definite overall project schedule» Last minute test notifications to SO/Transpower Better information dissemination down to field engineers» Vital information to be made available to commissioning engineers
MW System Frequency 12 November 2013 System Disturbance 23 60 51 50 49.94 48.80 50.5 50 40 49.5 30 49 48.5 20 10 47.99 48 47.5 0 3.32 47 46.5-10 Time 46
Part 2 THI Turbine & Generator Tests and Mathematical Model
Governor Testing 25 EIPC requirement is to provide a verified set of modelling parameters Digital governor Therefore frequency injection selected Over frequency more relevant for geothermal Less influenced by steamfield performance
Frequency Injection 26
Gross Active Power & Speed Injection signal Turbine Speed (rpm) Over Frequency 27 140 Te Mihi Over Frequency Injection Test 3004 120 3002 100 3000 80 60 2998 2996 2994 Speed Injection Signal (rpm) Gross Active Power (MW) Turbine Speed (rpm) 40 2992 20 2990 0 2988 0 20 40 60 80 100 120 Time (s)
Excitation Testing 28 EIPC requirement is to provide a verified set of modelling parameters No significant difference for geothermal units to their hydro / thermal counterparts Step in AVR voltage setpoint tests both with PSS on and off Limiter tests (over & under excitation limits)
PSS Testing 29
Modelling Results 30
Modelling Results 31
Part 3 Market
Unit versus Station Risk 33 During commissioning both units are modelled as a Contingent Event (CE) risk status until each unit has passed its system ride through test (SRT). Proposed code changes in 2012 looked at causer pays for the additional reserves to cover unproven plant Contact went with unit risk and dispatch to offset the station risk - gap in the commissioning of the two units Downside is that metering changes are required
SPD Modelling 34 Post commissioning: Retain unit dispatch Move to station dispatch (metering changes required)