Author: Alkiviadis Tromaras (CERTH)

On May 9th, 2024, the Di-Hydro Coordinator CERTH and partner ATLANTIS have carried out a technical visit to PPC’s Thissavros plant. Together with the Thisavros Plant Manager and Di-Hydro Partner PPC, the visit focused on discussing with the plant director the objectives of the Di-Hydro project and the activities that will need to be carried out in this specific plant within the project’s framework.

Specifically, PPC is participating in the Di-Hydro project in use cases related to digitisation of operations and maintenance with three different plants Ilarionas, Thisavros and Pournari. In fact, the activities cover the installation of a sensor node developed by CERTH that detects and records acoustic emission activity, vibration, magnetic flux variations, temperature and humidity. In addition, the CERTH sensor is capable of detecting crack growth formation for condition monitoring and structural health monitoring purposes on rotating machinery or infrastructure. ATLANTIS is participating in the development of diagnostic and prognostic AI-based models, based on historical and sensor data from the hydropower plants.

Figure 1. Penstock ball valve and flange

Figure 2. Oil pressure system motors

Di-Hydro’s Thissavros Use Case

Hence, the aim of the visit was to observe the characteristics of the Thisavros HPP and discuss with the plant director various operational and maintenance issues. This was crucial in order to identify the potential locations of where the sensors would be placed in the plant depending on the needs. In addition, underwater inspections using a remote underwater vehicle will be carried out by CERTH at the water intake tower.

Some of the potential locations for sensorisation where the following:

• Penstock ball valve (see Figure 1)
• Oil pressure system motors for controlling the Francis turbine fins ( see Figure 2)
• Air compressor units (see Figure 3)
• Water pumping system motors ( see Figure 4)
• Partial discharge on stator windings causing deterioration of the coating
• Transformer condition monitoring.

Figure 3. Air compressor units

Figure 4. Water pumping system motors

About the Thissavros Dam

The Thissavros Dam is a rock-fill dam on the Nestos River in the regional unit of Drama in the north-eastern portion of Greece. It is 21 kilometres (13 mi) north of Nikiforos, and 21 kilometres (13 mi) northeast of the town of Drama. The 172-metre (564 ft) high dam is the tallest in Greece. It was constructed between 1986 and 1996.

The purpose of the dam is irrigation and hydroelectric power production. Its reservoirs helps irrigate 80,937 hectares (200,000 acres) and its power station has a capacity of 384 megawatts (515,000 hp). The power station is a pumped-storage type, which allows it to not only generate power, but the turbines can reverse and pump water back into the reservoir. Power generation occurs during periods of high demand and pumping during those of low demand, such as at night.

Figure 6. Mock-up of the water intake tower