# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 2 Literature Review
### Environmental Impact  
The interaction between PQ and the environment is twofold: on the one hand, natural factors can cause PQ events, and on the other hand, there is also an anthropogenic component when PQ events affect the environment. The effects range from small voltage sags to power system blackouts and serious ecological consequences. PQ events can disable critical equipment whose operation is essential for human and environmental security. These include fire-fighting pumps, equipment preventing air pollution (such as electrostatic precipitators which remove particles from a flowing gas using the force of an induced electrostatic charge, and flue-gas desulfurization process during which sulfur dioxide is removed from exhaust blue gasses of fossil-fuel power plants as well as petroleum refineries, waste incineration, cement and lime kilns), wastewater treatment facilities, as well as nitrogen loops used for chemical inerting (to reduce and inhibit undesirable chemical reactions with oxygen), and cooling loops in nuclear power plants, nuclear waste repositories, and oil refineries [1,2]. To start with, among the primary causes of PQ events, in particular supply interruptions, are natural hazard events such as windstorm, lightning, earthquake, tsunami, and flood. The example of the Fukushima Daiichi nuclear disaster, which was caused by the 2011 Tohoku earthquake and tsunami as well as their impact on both the power grid supplying the power plant and the nuclear reactor cooling systems, has already been discussed in [2]. The impact of the extreme weather on the reliability of the United States power system, including the history of blackouts, is discussed in [41]: between 1984 and 2012, as can be seen from the graph given in [42] (p. 3), the annual number of the major outages (i.e., those that affected at least 50,000 customers) caused jointly by the categories labelled \"storms and severe weather\", \"cold weather and ice storms\", \"hurricanes and tropical storms\", \"tornadoes\" and \"extreme heat and wildfires\" increased drastically (including because of stricter reporting requirements), and between 2003 and 2012, \"80% of all  
Figure 4: Comparison of EN 50160:2010 voltage harmonic levels (up to the 25 th) with IEC 61800-3:2022 immunity requirements (up to the 40 th). The absence of a column means that there is no requirement—it is under consideration and therefore not yet given. outages were weather related\". In [43], a focus is made on a qualitative assessment of the impact of so-called Winter Storm Uri, a series of winter storms in Texas on 13-17 February 2021, on power system resilience: abnormally cold weather led to widespread disruption in electricity generation (particularly from natural gas) and to a spike in electricity demand (which exceeded the projected winter peak demand of 57.7 GW by over 10 GW), the grid operator enforced load shedding (which prevented the frequency from falling below 59.3 Hz), the state suffered a major power crisis. Analysis of severe scenarios and their consequences is very important in order to properly prepare for them and perhaps even to prevent (avoid) them: conceptually, [41] illustrates this process with the resilience trapezoid by dividing the timeline into the pre-disturbance resilient state, the disturbance progress, the post-disturbance degraded state, the restorative state, and the post-restoration state, while [43] illustrates this with a resilience curve by dividing the timeline into preparation, absorption, recovery, and adaptation phases. In addition to extreme situations, there are also smaller-scale but no less important events that cause short circuits and worsen grid reliability indexes. Thunderstorms are directly related to the occurrence of voltage spikes and transients, high winds and minor storms cause conductor gallop, increase a risk of tree toppling and their branches falling. However, this topic has not been deeply explored in the literature and remains an open research field [2,8].