Hydropower automation from a single source

Thyricon employs state-of-the-art industrial programmable logic controllers for performing the digital voltage regulation tasks, stator and rotor limiting functions, power system stabilizing and interface with other systems in the power plant. The regulation and control software are engineered according to IEEE standards, which guarantee the best system behavior as well as reliable and safe operation within the generator limits.

The controllers are based on standard Siemens electronic components and parts. The program language of the Thyricon controllers is identical to the Siemens automation product line, which facilitates the handling of the excitation system. Therefore, training and maintenance becomes easier and faster.

In HyCon Thyricon static excitation systems, the field winding of the generator is fed directly by a fully controlled thyristor rectifier bridge. The direct access to the rotor winding is the reason for the superior dynamic characteristics of such systems. State-of-the-art power electronics combined with a self-excited configuration enhance the reliability of the static excitation system, as its power part is independent from the rest of the power plant. The high ceiling voltage capacity and wide-range operating voltage of the rectifier bridge guarantee that Thyricon continues working even during severe voltage drops in the power system.

Benefits:

• Superior dynamic control characteristics
• Negative field forcing capabilities
• Rotor temperature estimation (field voltage and current)
• Static power part, no rotating machines required

Rotating exciters may be used instead of static exciters, in which case, a directly driven AC exciter machine with the rectifier mounted on the generator shaft is employed. The main advantage of this solution compared with DC exciters is that the problems associated with the commutator and brushes can be completely eliminated. The brushless system eliminates the slip rings and thus all current-carrying brushes. The brushless excitation system is used for high-speed synchronous machines with horizontal shafts as well as for hydropower generators. Although typically used in smaller generators, larger machines have also been employing such systems to pursue lower maintenance costs, if it fits to regional grid and customer requirements. Although typically used in smaller generators, depending on regional grid and customer requirements, larger machines can benefit from the use of such systems to pursue lower maintenance costs.

The outstanding feature of Kaplan and bulb turbines is their high efficiency in a wide head range thanks to adjustability of wicket gates and runner blades. The Kaplan optimization module corrects an inaccurate dependency automatically. The optimization is done during normal operation of the machine. The optimization method adds small changes to the wicket gate and runner blade opening. Thanks to the steady machine flow, the disturbance of the machine operation is negligible.

Voith offers a module to fully and automatically optimize the cam curve that directly results in optimizing the profitability of the hydropower plant.

The HyCon plant optimization distributes the power to the units in operation in the most efficient way, taking into consideration deviations in design, efficiency and water passages. Thus, plant optimization helps to save valuable water.

The optimization methods implemented in the HyCon plant optimization module are applicable for all types of hydraulic machines, whereas the expectable benefit by tendency is higher for Francis units than for Kaplan turbines. A detailed plant model with characteristic curves and physical models for turbine, generator, shut-off and closing devices as well as water passages is used to perform the optimization.

The Voith HyCon joint control (JC) is an integral part of the HyCon control system. It is the approved approach to optimize the active and reactive load distribution. Accordingly, the discharge distribution is optimized in plants with multiple units.

HyCon water management control is the central element in the management of your water storage facility. Water resource management employs weirs, locks and the turbines in hydroelectric plants. Efficient and optimized operation of these installations must always comply with governing water management regulations and should be automated to the greatest extent for efficient and optimized operation. Thanks to the many years of experience and gained expertise with its HyCon water management control, Voith can satisfy all requirements associated with stored water facility management.

The OnCare.Health Hydro monitoring module evaluates all measurements and characteristic values as a function of operation mode and operation point and includes logical functions based on parameters that generate trip signals to be transferred to the mechanical protection of the unit. The following monitoring functions are supported by the OnCare.Health Hydro concept:

• Shaft, bearing, turbine head cover, stator core, labyrinth, end-winding and axial vibration
• Partial discharge
• Generator air gap
• Magnetic flux
• Among others: temperature, pressure and shaft current 

Cavitation is an undesired hydraulic phenomenon that potentially limits the operational range of hydraulic turbines. It causes noise, vibrations and can even erode the surface of turbine components. OnCare.Health cavitation monitoring provides reliable online information about the cavitation state inside the hydraulic machine. This module helps you to find the right balance between operational requirements and economic performance.

Key benefits of OnCare.Health Hydro cavitation monitoring are

• Reduced maintenance costs by up to 30% thanks to extended maintenance intervals, early detection of initial cavitation damage and reduction of operation loss
• Increased availability by up to 0.5% with better planning of needed repairs and reduced inspection and maintenance stand-still time due to cavitation damages
• Optimization of operation and compensation through early detection of untypical behavior, avoidance of cavitation zones and quantification of cost for operation in cavitation condition

Voith is currently running co-developments with dedicated customers to continuously improve and extend the functionality of OnCare.Health Hydro cavitation monitoring.
Become one of our first pilot customers and benefit from additional, comprehensive benefits of cavitation monitoring.

In order to extend the benefit for the plant operator, the system must be able to efficiently support condition-based maintenance strategies. Our OnCare.Health Hydro modules are specifically designed to meet these advanced requirements:

• Highly sensitive measurement technology with adapted analysis techniques.
• Diagnostic intelligence for proper selection of specific parameters and comparison of the measured values with the expected behavior depending on specific plant conditions and machine operation modes.
• Tailor-made systems to meet specific conditions such as very low speed or various operating modes with highly volatile excitation requirements.
• Precise machine monitoring through intelligent measuring and analysis systems covering analytical evaluation of pre-processed values from the measurement device – as for example frequency analysis providing frequency selective observation results – and the calculation of further hydropower specific characteristic values.

OnCare.Health Hydro, with its flexibility and adaptive modular configuration, provides a powerful tool for reliable diagnostics for safe operation at all times, main component towards predictive maintenance. A knowledge database automatically processes the results of the analysis. The database is adapted individually to each power unit and is largely based on fully customized dynamic machine models. A mathematical model of the unit ensures quantitative and qualitative evaluations since it incorporates the highest process know-how and all existing mechanical couplings. In addition, operational experience can be integrated into the knowledge database.