It is generally expected that power systems worldwide will experience an increase in harmonic distortion as the green transition progresses.

At lower voltage levels, an increase in harmonic generation is expected, caused by widespread photovoltaic (PV) generation, usage of energy storage, electric vehicle charging/discharging and increasing converter-interfaced loads at a domestic level.

Larger and more frequent voltage variations are to be expected that can lead to both undervoltages or overvoltages. This effect will be strongest in areas of the power system having low system strength.

In distribution networks, over voltage can lead to excess energy consumption, transformer core saturation and stressing of insulation, leading to premature failure.

Undervoltage can lead to reduced energy consumption, malfunctioning of high-intensity discharge lamps, reduction of torque developed by mains-connected motors as well as overcurrent with associated accelerated aging as a consequence.

The proliferation of converter-interfaced renewable generation connections, with intermittent power output, combined with a reduction in system strength through displacement of conventional plants, results in higher volatility in the system voltage at the transmission level.

Voltage dips, typically caused by system faults, transformer energization, or large motors starting, can become more frequent and severe in distribution networks.

Technologies such as photovoltaic systems at the LV level are taking place as single-phase connections, which introduces unbalances into the system.

They are most likely driven by:

• Asymmetrical three-phase loads or unequal distribution of single-phase loads.
• Intermittent loads at the low-voltage level - such as electric vehicle charging points and heat pumps - will have an increased power capacity and are likely to introduce more imbalance.

• Overheating of three-phase motors and stress leading to mechanical failure
• Reduced equipment lifetime
• Lights that dim every time a large motor starts, posing a safety concern and reduced productivity
• Poor power factor and penalties on electricity bills
• Higher CO₂ emissions due to inefficient operation
• Unwanted tripping of contactors and control relays
• Process stoppage, production losses and data corruption
• Non-compliance with grid codes
• Additional service and maintenance costs

• Derating of induction motors, increased heating and losses, and increased thermal stress on VSDs due to voltage unbalance
• Overheating of conductors, transformers, capacitor banks, motors and generators due to harmonics (especially with EV charging on the increase)
• Voltage variations that affect sensitive loads
• Power variation and load pulses (eg, due to solar disturbance / power intermittency in photovoltaic output)
  • Power disturbance (on the scale of seconds) causes flickers
  • Power disturbance (on the scale of minutes) requires immediate regulation using power generation reserve from the grid in on-grid mode, leading to wear and tear of the grid components and maintenance costs
  • Ramp up/ramp down of diesel generators in off-grid mode, which will lead to reduced efficiency of the diesel generator

• High stress on generators leading to premature failure and higher running costs
• Reduced lifetime of equipment (eg, overheating of transformer due to harmonics)
• Insulation breakdown
• Solar/wind generation inability to connect to the grid in case of overvoltage or undervoltage or if harmonic pollution emitted is too high
• Reduced efficiency and high cost of electricity due to losses on the grid
• Grid instability and reduced network capacity
• Increased downtime

• Malfunction of IT equipment and data corruption
• Tripping of VSDs and cooling systems
• Inefficient energy usage (ie, high PUE)
• Higher CO₂ emissions due to inefficient operation
• Increased downtime, penalties for outages and data loss
• Additional service and maintenance costs

• Malfunction of equipment (washing machines, dish washers, etc.)
• Overheating and increased stresses on motors, leading to failure of HVAC and pump systems
• Flicker on computer/TV screens
• Poor power factor
• Harmonics resulting in inefficiency and higher energy bills
• Lost power and data on critical equipment
• Electromagnetic interference with communication systems.
• Unbalanced loads
• Peak demands and their time of occurrence
• High neutral currents

• Non-compliance with grid codes
• Penalties on electricity bills
• Frequent outages and downtime
• Reduced operational efficiency

• Non-compliance with grid codes
• Not allowed to connect to the grid
• Increased on running costs
• Frequent outages and downtime