Solvina - Optimisation of Cogeneration Plants

Solvina is an expert in optimising the dynamic performance of cogeneration plants and the supply of heat, steam and power to production processes. We work in plants such as pulp and paper, steel, chemical and petrochemical. We focus on the following areas:

• Steam system control
• Turbine control / island operation
• Generator control
• Power grid operation
• Operator training

Solvina improves the performance of existing plants and ensures the right design in new build projects and refurbishment projects. Our process and power control experts design and implement superior systems and control for efficient and robust operation. Huge savings are achieved by decreasing outage time and energy losses.

Optimal steam system control

Solvina has developed advanced methods to increase the availability and stability of steam systems in cogeneration plants. The steam system of an industrial cogeneration plant is far more complex than the systems of a conventional power plant since the steam consumption varies a lot, often momentarily, and there are several steam grids with different pressure. This requires expert knowledge when designing the process and its controls.

By developing control strategies in dynamic simulators Solvina achieves fewer disturbances and more efficient commissioning after planned outages. Simulators are used for the design of process equipment since both steady state (BOP) and dynamic simulations reveal the required performance. Simulation is used in the whole project process, from conceptual design, purchase process, fine tuning and commissioning, to training.

Solvina develops and improves process control systems for boilers, steam bypass valves, turbines and steam accumulators. Our methods ensure the best possible process control for all the critical operating conditions and events in the actual plant.

Turbine control and island operation testing

During power system disturbances and interrupted power supply, a process plant can continue running if it can transfer to island operation and if its island operation capability is sufficient. However, as conditions can be tough and sensitive, islanding is complicated. Performing a black start can be even tougher. Solvina has unique experiences and knowledge of island and in-house operation. Our test methodology, using the real-time simulator SolvSim® Power Station, enables safe island and in-house operation testing and development.

A turbine governor has many control modes and functions for turbine protection. All these functions have an effect on plant performance. Solvina optimises the control modes for best possible performance and also tunes limiters and protections to allow the best possible dynamic performance while still maintaining the protective function. A simulator connected to the governor control is used for tuning frequency response in normal and in island operation.

This simulator is a hardware-in-the-loop simulator and allows fast and accurate tuning during full operation of the plant. Solvina has carried out successful tests in many industry sites and has achieved vastly improved island operation capability, saving millions in improved availability of the production process.

Generator control systems

The automatic voltage regulator (AVR) of generators has several control modes and modules for limitations and stabilisation. Solvina performs tuning of AVR systems and stabilisers to meet grid code requirements and local requirements due to parallel operation and load variations. Dynamic simulation of the surrounding power system is performed to get the best possible result. The settings are followed up in the commissioning phase.

Power system analysis

Using modern simulation tools, Solvina performs power system analysis as a part of system design, relay protection coordination and operation planning. In cogeneration plants it is also important to achieve the right control functionality to handle the different events that occur. By simulating these events, the control can be optimised to handle the events in the best possible way. Motor starts, turbine trips, island mode transition and motor shut down are important events that are considered.

Power plant operator training

Plant operation management is a critical factor for productivity and plant efficiency. Solvina conducts training programmes for operation and maintenance staff to increase the understanding of plant behaviour.

The main focus is to learn about the functionality of the processes and systems and the physical laws governing their behavior. Complex theory is explained in an intuitive and practical manner, and training simulators are used to visualise and verify the theory, and to do training. The goal is that operators will be able to take faster and more accurate decisions, based on profound knowledge of the plant, thereby achieving better productivity and efficiency.