CASE STUDY:PARTIAL-LOAD HEAT RATEIMPROVEMENTREDUCES FUEL COSTS AND DELIVERSPOSITIVE CASH FLOWSTOMONI®
Performance Improvement andFlexible OperationTurbine Cooling Air Optimization
PLANT DETAILS• Genesis Energy Huntly Power
Station Unit 5 commissioned
in June 2007
• 385 MW CCGT,
originally base loaded• Huntly, Waikato, New Zealand
EQUIPMENT NOTES• Mitsubishi Power Turnkey
Plant Supply• M701F Gas Turbine andSteam Turbine• DIASYS Netmation®
Control Platform• TOMONI Solutions Installed:2021

CHALLENGE
The 385 MW CCGT unit #5 at Genesis Energy’s Huntly Power Station has been in service since June 2007, mainly in base-loadoperation. Due to the increase of renewable energy in the New Zealand market, operation of Huntly is shifting toward morepartial-load operation. Huntly needed to find ways to improve efficiency during partial-load and load-following operation. For
units such as Huntly intended for base-load operation, turbine cooling air (TCA) fans operate at a fixed speed, and rotor coolingair (RCA) temperature is set for the highest ambient temperature at base load to ensure safe operation. This results in a TCA
outlet temperature below the target temperature when the unit is at partial load or the ambient temperature is low, creating
an opportunity to improve plant efficiency.

SOLUTIONRESULT

Digital solutions can improve operational
flexibility and efficiency for partial-load
operation in several areas, and one
particularly beneficial application for
Huntly was upgrading the control of the TCA fans thatmanage rotor cooling air temperature. The original control
method provides enough cooling function to cover thevarious operational conditions from the point of view ofreliability of turbine parts. However, excessive coolingsometimes induces plant performance loss. The TOMONI
Turbine Cooling Air Optimization solution provides more
precise control of the TCA fans to optimize RCA
temperature through control logic modifications and powerelectronic inverters. This improves efficiency at all loads bymaintaining an optimum RCA temperature based onreal-time operating circumstances.

The solution achieved a partial-load combined-cycle heatrate improvement of up to 0.6%, which was consistent
with the forecast for this project and significantly reduces
fuel cost and emissions. Fuel cost savings from 0.6%partial load heat rate improvement vary, but can be in therange of 200,000-800,000 USD per year depending onfuel cost and unit dispatch. In addition, as the operatingload range changes during normal operation, the TOMONI
Turbine Cooling Air Optimization solution automaticallycomes in and out of service to maximize the economic
benefit. Genesis only uses the solution when they feel itis beneficial, based on the plant operational mode andestimated heat rate improvement. They have seen thebenefits and have continued to use the TOMONI solution.

Another important solution for the plant was the payment
method called “pay-as-you-go,” which was applied for theinitial capital investments for the upgrade of the TCA fansand control system. In this investment model, there iscost only when the digital solution is used, avoiding initialinvestment and maintaining positive cash flows.

DATA FOUNDATION& ENABLERS

FLEXIBLE
O&M
OPTIMIZATIONOPERATIONSSOLUTIONSPERFORMANCEIMPROVEMENTIMPROVEMENTSOLUTIONSFLEXIBLEOPERATIONSOPERATIONSSOLUTIONSDATAFOUNDATIONFOUNDATION& ENABLERS& ENABLERSTOMONI Turbine Cooling Air Optimization is one of manysolutions available from Mitsubishi Power to optimize
O&M of the entire plant. Other TOMONI solutions deployedat Huntly include KPI Analyst data visualization, Pre-ACT
anomaly detection and Post-ACT alarm guidance.

“All thermal generation throughout the world needs

to respond to the significant growth in renewablegeneration, by effectively and efficiently filling the gaps
which renewable generation can leave due to variableclimatic conditions, and to cover peak demands. TOMONITCA Optimization is an innovative solution provided byMitsubishi Power for partial load heat-rate improvement.
This has both reduced our fuel cost and reduced theenvironmental emissions without any major up-front
capital investment and only minimal expenses for on-siteenabling work such as cabling and installation support.”
O&M
OPTIMIZATIONPERFORMANCEPERFORMANCEIMPROVEMENTIMPROVEMENTSOLUTIONSFLEXIBLE
FLEXIBLE
OPERATIONSOPERATIONSSOLUTIONS Rob Schinkel
LTSA Manager, Huntly, Genesis Energy
TOMONI® is a suite of intelligent solutions that accelerates decarbonization with power plant design, O&M and system knowledge, together withstrong customer and partner collaborations. TOMONI leverages advanced controls, artificial intelligence and machine learning with multi-layered
cybersecurity to make energy systems smarter, more profitable and ultimately more autonomous on the road to a sustainable future.

O&M
OPTIMIZATION© Mitsubishi Heavy Industries, Ltd. All rights reserved. TOMONI® is a registered trademark of Mitsubishi Heavy Industries, Ltd.
Mitsubishi Power is a power solutions brand of Mitsubishi Heavy Industries.

Data Foundation & Enablers
O&M Optimization
Performance Improvement
Flexible Operations
METP-11DS43E2-A