Progressive OTS, Towards a Perfect Startup

The role of simulators in the power market is ever-expanding. In the 2012 report on operator training simulators, the ARC Advisory group declared:

“In the past, almost all simulators were purchased custom built for a new plant, used to train the operators, and then stored away for potential future use, since they were too costly to maintain. Today, organizations tend to take advantage of their investments in simulation models and OTS solutions over the lifespan of the plant, making both generic and plant-specific OTS systems more cost-effective investments.” 

-   ARC Advisory group, 2012


In addition to the traditional use for training, power plant EPCs and end-users alike are now able to utilize the same simulator platform to remove a large amount of risk and costs associated with some of the key factors in plant development. Today it is not uncommon for the cost of a well-planned simulator to be fully recovered before the plant comes online.

Having supplied high-fidelity simulators to the power market for over 30 years, Yokogawa has a great deal of experience in this area, and has played a major role in driving changes and innovation.

What follows is a short overview of DCS systems and high fidelity simulators, and a short case study of Loy Yang and their positive experience using this technology.

Integrated DCS and Simulator Development

Many years ago it was recognized that an integrated approach in both control system development and simulator development was necessary to realize the full potential of high-fidelity simulators. “Progressive OTS” as it is now known, is developing the OTS in parallel with the DCS design and configuration:

Figure 1: illustrates a full-integration model for consolidated DCS and replica simulator development.

In this approach, after an initial phase of independent development, control engineers and simulation engineers work together to verify the control logic design and implementation by using the simulator as a control test bed. This will allow the project team to:

  • Commission the DCS well in advance of being applied to the reference plant;
  • Develop and rigorously test high-level integrated control strategies;
  • Develop and rigorously test emergency control responses to plant disturbances or equipment failures;
  • Tune modulating control with a very high degree of accuracy.

Progressive OTS is a fully integrated development system – significantly reducing the time and cost associated with on-site commissioning – increasing efficiency. Furthermore, this ensures that the plant will operate consistently without interruption and manage disturbances without loss in generation, or damage to equipment.

It is important to note that several essential ingredients are required to successfully implement such a venture. This will need to be thought-out, strategically planned and implemented. The key ingredients are as follows:

The simulator as “Unit 0”

In order for the benefits of a high-fidelity simulator to be fully realized, it must be treated as “Unit 0” by all parties; the contract structure and schedule must support this. Companies that supply both high-fidelity simulators and control systems are able to offer a consolidated approach to simulator and DCS development, which allows end-users to reap the full benefits of simulator technology.

A stimulated control system

Virtual controller technology, such as Centum VP Test Function®, allows for transfer the DCS configuration, including graphics and logic, between the reference plant and simulator (and back) without the need for modification or translation. Once the logic is commissioned on the simulator, the DCS configuration folder can simply be copied to the plant platform and downloaded to the controllers – ready to begin commissioning.

High-fidelity process modeling software

In order to rigorously test the control system action, the process modeling software must be of a fidelity-level high enough to mimic actual plant behavior, based on design inputs only. Through a modular OTS, you are able to construct a full-scope replica of the reference plant; i.e. “Unit 0”. By simulating the individual characteristics of each piece of equipment in an integrated environment, the process model is able to accurately predict the dynamics of the plant to a degree of fidelity sufficient enough to conduct DCS development across all areas of control.

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Case study: Loy Yang

The AGL Loy Yang power station supplies approximately 30% of the power consumed in Victoria – the second largest state in Australia – through four 500+ MW conventional brown coal-fired power plants. Due to being a base load station and the inherent difficulties associated with transporting and burning coal with high moisture content – and with units having different turbine configurations – at Loy Yang station there is little margin for operation and control error in each unit. When the station moved from panel-based operation to DCS, three separate high-fidelity and full-scope simulators with the DCS were delivered. The project made significant achievements, including:

Figure 2: AGL Loy Yang Progressive OTS Simulator

  • Development and commissioning of all DCS logic and HMI for Loy Yang Unit 2 on a CS3000–based, full-scope high-fidelity replica simulator, including an emulated Siemens steam turbine control;
  • Development and commissioning of all DCS logic and HMI for the Loy Yang coal-handling plant (CHP) on a CS3000 – based, full-scope, high-fidelity replica;
  • Development and commissioning of all DCS logic and HMI for Loy Yang Unit 1 on a Centum VP R5-based full-scope high-fidelity replica simulator, including the Yokogawa Turbomachinery Control solution;
  • Training of all operators each of the plant areas prior to commissioning;
  •  Upgrade of the Unit 2 simulator to Centum VP R5
  • Combination of the Unit 1, Unit 2 and CHP simulators into a VMware ESXI-based single-server simulator solution;
  • Duplication of the single-server simulator to offer AGL Loy Yang two complete, full-scale replica simulators, each encompassing Unit 1, Unit 2 and CHP, allowing for parallel training courses to be run to meet AGL Loy Yang’s high requirement for operator accreditation.

To this day, the simulator is maintained by AGL Loy Yang and Yokogawa Australia including regular updates, enhancements, and control system testing. AGL Loy Yang believes the simulator to be an integral and critical part of their operations in power.