The New Role of Hydropower: Why Smart Monitoring is Now Essential

Thiago Kleis
3 days ago
3 min read

Updated: 12 hours ago

As the global energy transition accelerates, grid dynamics are rapidly changing. With more intermittent renewable energy sources like solar and wind coming online, hydropower is being pushed from its historic role as a baseload provider into a fast-response, grid-forming role.

From a grid perspective, this is a success story—hydropower is filling the gaps, absorbing volatility, and ensuring stability.

But for the asset owner? This shift comes with a silent cost: accelerated degradation of hydroelectric machinery.

From Baseload to Flexibility: A Mechanical and Thermal Shock

Hydropower machines—turbines, bearings, generators—were not historically designed for high-frequency cycling. They were engineered for long, stable operating periods. Today, due to solar and wind variability, hydro units may start and stop several times per day.

A real example: the chart below shows Portugal’s generation profile on August 27, 2025. Hydro output (blue) surges in the early morning and evening, bracketing the peak solar hours. That flexibility is critical—but it’s not free.

Power generation in Portugal 27/08/25 (Source: Antonio Vidigal)

What's Happening Inside the Machines?

Let’s break down what frequent cycling does to core components:

Generator Stator Winding

Every start and stop subjects stator windings to thermal cycling, causing expansion and contraction that leads to:

Low-Cycle Fatigue (LCF) — micro-cracks and delamination between copper and insulation.
Partial Discharge (PD) — initiated in micro-voids, eventually leading to insulation failure.

Ref: IEEE IEMDC (Kokko, 2011), Hydro Review (2021), CIGRE Technical Brochures

Hydro generator during maintenance (Source: IOP Science)

Turbine Runner and Bearings

Turbine Runner — faces mechanical stress and cavitation during transient flow conditions, accelerating fatigue.
Bearings — suffer wear during startup when hydrodynamic oil film is not fully formed, damaging Babbitt layers.

Ref: IOP Earth & Environmental Science (2023), Fusion Babbitting (2025), Int. Journal of Fatigue (2021)

This degradation leads to higher maintenance costs, increased downtime, and risks to grid reliability if units are unavailable during peak demand.

Hydro turbine runner with erosion (Source: Waterpower Magazine)

Condition Monitoring: The Shift to Predictive Maintenance

To adapt to this new operational profile, hydro operators need more than calendar-based maintenance. They need real-time, condition-based insight into their machines.

Key Monitoring Technologies:

Sensor Type	Targets	Detects
Vibration	Turbine, bearings, generator	Imbalance, misalignment, bearing fatigue, mechanical looseness
Air Gap	Stator / rotor	Core deformation, rotor eccentricity, insulation displacement
Magnetic Flux	Stator, rotor windings	Inter-turn shorts, winding degradation, rotor pole issues
Partial Discharge	Generator stator	Insulation aging, contamination, workmanship errors, loose contacts, voids, breakdown zones from thermal cycling

This isn’t just about collecting data—it’s about unlocking predictive intelligence that extends asset life and ensures generation readiness when it’s needed most.

Predictive maintenance in the context of the P-F curve (Source: ResearchGate)

AQTech + Megger: One Solution. Total Visibility.

Hydropower’s future depends on operational flexibility—but that flexibility must be sustainable. That’s why AQTech and Megger have partnered to offer a holistic condition monitoring solution, combining mechanical and electrical diagnostics in a single integrated platform.

Based on field data and industry research from CIGRE, the chart below provides a clear breakdown of the main failure mechanisms in hydrogenerators. As shown, insulation failures represent the majority at 56%, followed by mechanical damage (24%), thermal-related issues (17%), and bearing damage (3%).

source: CIGRE Study Committee SC11 (EG11.02)

This data reinforces the value of a comprehensive monitoring approach. By combining Megger’s expertise in electrical diagnostics, such as Partial Discharge and insulation condition assessment, with AQTech’s capabilities in mechanical and magnetic monitoring—including vibration, air gap, and magnetic flux—we offer a truly holistic condition monitoring solution. Together, we address the majority of failure modes that threaten hydrogenerator reliability.

A Unified CMS Approach:

Vibration Monitoring (AQTech) – Follows ISO 20816, targeting early-stage mechanical faults in turbines, bearings, and generators.

AQTech solution for bearing relative and absolute vibration

Air Gap Measurement (AQTech) – In compliance with ISO 19283, detects rotor eccentricity and core deformation.
Magnetic Flux Monitoring (AQTech) – Identifies inter-turn shorts and winding issues critical in high-cycling units.