# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 2 Literature Review
### Social Impact
* IEEE Std 1159-2019 and other IEEE PQ standards do not regulate PQ phenomena, except for IEEE Std 519-2022 [84] which sets limits for both voltage and current harmonics at a point of common coupling. Despite this, IEEE Std 1159-2019 is more informative than EN 50160:2010. * The harmonized standards under the EMC Directive 2014/30/EU contribute to PQ regulation. IEC 61000-2-2:2002 [85] specifies PQ requirements for public LV electricity networks and supplements EN 50160:2010 by expanding the requirements for voltage harmonic levels up to the 50 th, by introducing some requirements for inter-harmonics in the beat frequency range of 0.2-40 Hz (with the fundamental) based on a short-term flicker level of 1 for lamps operated at 120 V and 230 V, as well as by setting the requirements for ripple control system signals in the range of 110-3000 Hz. IEC 61000-2-4:2024 sets PQ requirements for industrial locations with a nominal voltage up to 35 kV, IEC 61800-3:2022--for current harmonic levels in networks with adjustable speed drives depending on the short-circuit power ratio at an agreed point of coupling (common or in-plant). IEC 61000-4-7:2002 [86], IEC 61000-4-15:2011 [87] and IEC 61000-4-30:2015 [88] define the methods for measurement and interpretation of PQ results and therefore play a central role in both EN 50160:2010 and IEEE PQ standards. In Lithuania, as in other European Union countries, EMC standards together with their normative references as well as IEC 61800-3:2022 are mandatory according to the principle of imperativeness of harmonized standards to ensure the compliance with the already mentioned EMC Directive 2014/30/EU. Probably the most famous example of PQ events is the voltage sag regulation in Sweden, at least just because it has been presented in the 5 th CEER Benchmarking Report [89] (2011). It is based on the so-called responsibility-sharing curve which divides the voltage-duration plane into three areas (Table 2): (1) voltage sags in Area A are considered as a normal part of operation, expecting that the equipment and installations are sufficiently resistant; (2) the network operator has responsibility to mitigate voltage sags in Area B as much as possible to achieve with state-of-the-art technology at reasonable cost, but no specific limit has been set for their quantity; (3) there shall not be any voltage sags in Area C. Additional information about PQ regulation in Sweden is given by [90] (2011)--the paper presents the division of the voltage-duration plane into three zones for voltage swell assessment in up to 1 kV networks, as well as requirements for the number of rapid voltage changes (taking into consideration both \(\Delta U_{\text{ss}}\) and \(\Delta U_{\text{max}}\) parameters) and duration of supply interruptions. The second example available in [91] (2023) is from the Netherlands. In this case, the voltage-duration plane is divided into four areas (Table 3) by setting a maximum number of voltage sags allowed based on a 5-year average: (1) sags in Area A are non-severe; (2) the limit in Area B1 for the MV grid is 3, and for the HV and EHV--1.2; (3) the limit in Area B2 for the MV grid is 4, and for the HV and EHV--1.2; (4) the limit in Area C for the MV grid is 4, and for the HV and EHV--0.4. When the limit is exceeded, the network operator shall carry out the investigation and find out the reasons. After the examining the examples provided, it is not difficult to understand that in order to define boundaries between a good, bad, and acceptable situation, a considerable amount of statistical data (monthly, annual) on the actual occurrence of voltage sags is required. Work towards this has already begun. For instance, the available statistical data of 2015-2018 are presented in the 7 th CEER Benchmarking Report [92] (2022, pp.