Control System Upgrade


The challenge

Hydro-Electrical plants in Greece play a significant role in the coverage of the energy demand of the country.  Hydro power plants are fast responding plants that are interconnected to the central dispatching system of PPC and are the primary source of peak power coverage.  As such, it is expected that the respond instantly and with great accuracy.

Almost all high capacity hydro-electric plants in Greece were controlled by a system known as GUC (Generating Units Controller).  GUK was not only an old technology system but was also slow, inaccurate and lacking the operational logic required by modern standards.  In addition, the GUK system required the constant involvement of the operator at each station in order to correctly and safely execute corrective commands to the units.

The replacement of the whole GUK system with a new, latest technology, system was needed.   The new system aimed at providing increased speed and accuracy of each hydro unit as well as being able to operate safely the Hydro units completely unattended.

PPC Gavdos Plant Upgrade

MAS solution

MAS was selected due to the company’s proven know how and expertise in Generation Management systems and Unit Control solutions.  MAS’s proposal consisted of latest technology automation systems with advanced control and protection logic that would replace all exiting automation.  Through the new system, each unit was individual control and contained local that facilities its independent operation and execution of remote commands.  A local SCADA system enables the operator to have a high level supervision of the station operation and to give corrective instructions if needed.

The overall system offers:

  • Complete electrical power measurements for all units
  • Independent KW PID control for each unit
  • Automatic execution of setpoint when operating under AGC mode
  • Automatic execution of setpoint when operating under Market mode
  • Manual mode as a backup operation
  • Load sharing between units when in automatic mode with special logic to avoid critical operating areas of the units.
  • HMI/Scada application with user friendly graphical pages and full historical log.

The whole project was undertaken by MAS on a turn-key basis and included all needed Engineering, Procurement, Development, Installation and Commissioning services. The new system was fully tested under all possible scenarios with great success.


Today, more than 10 all high capacity hydro-electric stations (32 units totaling 2GW) are fully equipped with the latest type control system from MAS that ensures maximum operational reliability combined with optimum system performance.  Moreover, it offloads the station operators as all central dispatching commands are executed automatically without the need for them to interfere and gives them the time to focus to the rest of the station’s systems.

MAS Control Systems achieved:

  • 150% faster response to implementing central power distributor set points.
  • 50% better control accuracy. Special algorithms also take care of unit allocation efficiency
  • 100% less operator interference

This results to significantly better economical results for the station which operates as a power producer while eliminating the economical penalties from the power network manager of Greece.