# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 2 Literature Review
### Social Impact
It is not a secret that AI-powered solutions, the internet of things, blockchain, digital twins, quantum computers, and many others are promising technologies for digitalization of energy systems [112; 113]. This should also be very useful for PQ monitoring systems. In addition to the internal functionality, in order to obtain more benefit, it is also necessary to ensure smooth interoperability with other Smart Grid applications, in particular advanced metering infrastructure (Figure 9), asset management, outage management, predictive maintenance, and relay protection and automation [1; 2; 8]. Despite the advantages provided, overreliance on digital technologies makes society more vulnerable in cases of their failure. Also, they are a potential target for cyberattacks. PQ application is not an exception--any part of a remote monitoring can be attacked, including data transmitters and receiver, communication channel, data processing and storage systems. For now, PQ data are only informative, but later, especially after integration with relay protection and automation, its importance will become critical, thus the strictest data security measures will have to be taken in order to ensure correct grid operation [1]. To continue, another aspect not explored in the literature is the role of PQ in ancillary and various other services. One of these is demand response, a service that provides an opportunity for customers to participate in power system operation by voluntary changing their consumption behavior, for example, in order to receive financial benefits. More information about demand response, its programs and effects on supply-demand graph can be found in various sources, for example, in [114]. The opposite of demand response  
Figure 9: An example of the system architecture of advanced metering infrastructure and its integration with PQ and other necessary Smart Grid applications [113]. is automatic frequency unloading (also known as load shedding), which is not voluntary. Considering the above, cases when PQ event caused damage can be divided into routine work mode and unplanned (voluntary) work mode. Despite the advantages provided, let us take a closer look at demand response through the prism of PQ by mentioning the following situations:  
* The increase in wind park generation during windy weather can increase flicker level. Although the flickers do not cause downtime [19], they affect occupational health. * The increase in solar park generation during sunny weather can correlate with the level of harmonics injected into the grid. * On request to increase consumption, the industrial company launched many electric motors, variable-frequency drives and electric arc furnaces, and its neighbors was affected by the caused voltage sags, produced harmonics and flickers (respectively). * After increasing the consumption of an industrial company, a short circuit occurred in its internal network, which affected both the company itself and its neighbors. * Increased consumption had need of additional staff. The lighting was switched off by a voltage sag and, as a result, an employee who worked extra hours was injured. * The consumption was increased due to the increase in wind park generation during stormy weather, and a lightning strike (voltage transient) damaged the additionally connected end-user equipment.