Distribution networks are entering a phase of greater technical demand. They no longer transport energy in a single direction or serve relatively predictable consumption profiles. Today, they must accommodate new electrical uses, distributed generation, self-consumption, electric vehicle charging points and a growing presence of power electronics-based equipment. All of this is changing power flows, voltage levels and the operational behaviour of the grid.
In this context, ensuring continuity of supply is no longer enough. Distribution companies also need to understand how energy is being delivered: at what voltage level, with what stability, with what degree of distortion and under which real operating conditions.
This is why power quality has become a key indicator for operating safer, more efficient networks that are ready for the energy transition.
Power quality refers to the behaviour of the voltage supplied through the electricity network. It is not limited to checking whether there is supply or not, but analyses whether the waveform and its electrical parameters remain within suitable conditions for grid assets and connected equipment.
The most common phenomena associated with power quality include:
- Voltage variations.
- Voltage dips and overvoltages.
- Short interruptions.
- Phase imbalances.
- Harmonics.
- Flicker.
- Rapid voltage changes.
- Waveform distortion.
These phenomena can originate in the medium-voltage network, the low-voltage network, substations, switching operations, industrial loads, power electronics or customer installations. This is why their analysis requires an integrated view of the network.
Monitoring power quality enables a distribution company to move from a reactive model — based on complaints or failures — to a proactive, data-driven approach. Continuous monitoring of voltage levels, imbalances, dips, overvoltages, harmonics, flicker and other electrical phenomena helps identify abnormal patterns, locate critical areas and prioritise actions before problems escalate into major incidents.
From a technical perspective, power quality directly impacts three key dimensions of grid operation:
- Safety and reliability: it helps reduce the risk of failures, nuisance tripping, overheating and premature asset deterioration.
- Energy efficiency: it supports the identification of additional losses, phase imbalances and non-optimal operating conditions.
- Customer-perceived quality: it facilitates the explanation, prevention and resolution of incidents that may not appear as long outages, but still affect the operation of equipment and processes connected to the network.
From a regulatory perspective, quality of supply is framed within the European electricity market legislation, particularly through Directive (EU) 2019/944, which establishes common rules for the internal electricity market, and Regulation (EU) 2019/943 on the internal electricity market. These texts define the general framework, while the specific requirements related to power quality, continuity of supply, measurement methods, admissible limits, responsibilities and reporting obligations are developed through the national regulation of each country.
In addition, the technical assessment of power quality is commonly based on standards such as EN 50160, which specifies the main characteristics of the voltage supplied in public low-, medium-, high- and extra-high-voltage networks under normal operating conditions, and IEC 61000-4-30, which defines measurement and interpretation methods for power quality parameters.
Therefore, for a distribution company, it is not enough to simply record electrical events. It is necessary to work with traceable, comparable and contextualised data linked to the real operating state of the network and to the applicable regulatory framework in each market. Only then does power quality stop being an isolated monitoring signal and become a tool for diagnosis, justification of corrective actions, investment prioritisation and improvement of quality of supply.
1. Overloads and overheating in grid assets
Imbalances, overloads, harmonics or transformer saturation can increase the temperature of conductors, connections, fuses, low-voltage panels and transformers. Even when they do not immediately cause a failure, they can accelerate component ageing and increase the risk of faults.
In distribution networks, continuous data availability makes it possible to identify the most critical areas, prioritise preventive maintenance and reduce unnecessary field interventions.
2. Additional energy losses
An unbalanced network or one affected by waveform distortion may operate less efficiently. This can lead to higher-than-expected technical losses and reduced use of available network capacity.
Analysing power quality together with loads, phases, topology and real measurements helps identify where losses are concentrated and which actions can provide the highest technical and economic return.
3. Phase imbalances
Current imbalance in three-phase networks affects both system efficiency and the safety of connected equipment. It can increase the risk of overheating, conductor failures, harmonic distortion and protection trips.
For a DSO, identifying and correcting imbalances helps improve quality of supply, reduce losses and extend asset lifetime.
4. Voltage dips, overvoltages and flicker
Voltage dips, overvoltages and flicker can cause equipment resets, process interruptions, protection trips or unstable operation of sensitive loads. In industrial and commercial environments, or in automated processes, these phenomena can have a direct economic impact.
Having access to electrical records and correlating them with network events makes it possible to determine whether the issue originates from a switching operation, an upstream disturbance, a specific load or a local operating condition.
5. Power quality issues in medium-voltage networks
Although many of the effects of poor power quality are perceived in low-voltage networks, their origin is not always located there. Medium-voltage networks can be a major source of disturbances, especially in grids with high penetration of distributed generation, industrial loads, transformers operating under abnormal conditions or frequent switching operations.
In medium-voltage networks, voltage dips, transient overvoltages, imbalances, harmonics, flicker and rapid voltage changes may occur. These phenomena can propagate downstream through transformers and affect both end customers and utility assets.
The most common impacts include nuisance protection trips, unstable operation of sensitive industrial equipment, increased technical losses, higher electrical stress on transformers and lines, reduced asset lifetime and customer complaints even when there has been no clear interruption of supply.
For this reason, power quality must be analysed with an integrated MV+LV approach. It is not enough to study the point where the symptom appears. Utilities need to correlate medium-voltage data, low-voltage measurements, transformer information, smart meter data, sensors and operational systems to understand whether the problem originates in the customer installation, the LV network, the transformer or upstream in the MV grid.
6. Failures in customer equipment and complaints
Customers may perceive poor quality of supply even when there is no prolonged outage. Flickering, micro-interruptions, voltage fluctuations or repeated equipment malfunctions create a negative user experience and may lead to complaints.
For the utility, having access to measurements and analytics enables a more objective analysis of complaints, root cause identification and the provision of technical evidence.
7. Reduced capacity to integrate new loads and distributed generation
Electrification is bringing new loads and distributed energy resources to the grid: EV charging points, heat pumps, self-consumption systems, batteries, distributed generation and power electronic loads. These elements can modify power flows, load profiles and voltage conditions.
Without adequate power quality monitoring, it becomes more difficult to understand the real hosting capacity of the network, anticipate constraints or define efficient investment strategies.
Power quality monitoring only creates value when data is transformed into actionable information. Recording electrical events is not enough — they must be contextualised.
A distribution company needs to understand in which transformer substation the problem occurs, which feeder or phase is affected, which customers may be impacted, and whether the issue is related to overloads, phase imbalance, neutral loss, switching operations or upstream disturbances.
This is where distribution grid digitalisation becomes especially relevant. Combining data from smart meters, transformer substations, sensors, GIS, SCADA, AMI/MDM systems and advanced analytics makes it possible to build a much more accurate view of the real operating state of the network.
For years, advanced monitoring has mainly focused on medium- and high-voltage levels. However, many of the current challenges linked to the energy transition materialise in low-voltage networks and are closely connected to medium-voltage behaviour.
Low voltage is where many new electrical loads are connected, where much of the distributed self-consumption appears, and where the grid experiences the highest variability due to the aggregation of thousands of individual behaviours. Medium voltage, meanwhile, directly influences downstream stability and can be the origin of disturbances that eventually appear at supply points.
This is why combined MV and LV observability is essential to:
- detect incidents before they escalate;
- correlate power quality events with specific assets;
- reduce unnecessary field interventions;
- prioritise investments where they provide the highest value;
- improve continuity and quality of supply;
- optimise the lifetime of transformers, lines and equipment;
- prepare the grid for new demand, generation and flexibility scenarios.
Integrated power quality: from disturbance detection to operational action
Power quality should not be analysed as a collection of isolated electrical events. A voltage dip, overvoltage, phase imbalance, harmonic distortion or flicker event may have different causes and propagate differently across the network. For a distribution company, the real value lies not only in detecting the disturbance, but in understanding where it originates, which assets are affected, which customers may be impacted and which actions should be prioritised.
At Ariadna, power quality is integrated into the advanced analytics platform 🔸ariadna Smart IoT Platform🔸, combining data from sensors, smart meters, network topology and operational events. This approach enables utilities to move from simply “seeing alarms” to diagnosing, prioritising and acting on the issues that truly compromise quality of supply.
This holistic approach is especially relevant in increasingly dynamic distribution networks, where disturbances may be linked to overloads, phase imbalance, transformer saturation, incipient asset failures, power electronics, distributed generation or new loads connected to the grid.
By integrating power quality data with topology, network events and real field measurements, utilities can:
- contextualise each disturbance within the real operating state of the grid;
- distinguish between isolated incidents and recurring problems;
- identify whether the origin is located in LV, MV, the transformer substation or the customer installation;
- prioritise actions according to technical, operational and economic impact;
- reduce diagnosis times and unnecessary field interventions;
- improve quality of supply through data-driven decisions;
- aggregate power quality monitoring by geographical area.
Aggregated power quality monitoring by geographical area makes it possible to obtain comparable KPIs by region, transformer substation, feeder or municipality. This approach helps identify critical areas, analyse recurring disturbances, prioritise actions and provide traceable evidence to comply with regulatory reporting requirements and quality metrics.
In this way, power quality stops being only a monitoring metric and becomes an advanced operational tool. The goal is not simply to record events, but to transform electrical data into actionable decisions that help protect assets, improve continuity of supply and optimise network operation.
Conclusion: you cannot manage what you cannot observe
Power quality is a critical element for ensuring a safe, efficient electricity supply that is ready for new energy uses. Monitoring it helps protect assets, reduce losses, improve customer experience, optimise investments and move towards smarter grid operation.
The value is not only in measuring. It lies in turning dispersed data into diagnosis, priorities and decisions: what problem exists, where it occurs, why it happens and which action makes the most technical and economic sense.
In a scenario of growing electrification, distribution companies that monitor power quality more effectively across medium- and low-voltage networks will be better prepared to operate more complex grids, integrate new energy resources and maintain reliable supply over time.
