# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 2 Literature Review
### Social Impact  
From our point of view, the social impact of PQ can be explained through the prism of both responsibility and liability. It consists of at least three components: (1) responsibility for network pollution with conducted electromagnetic interference, as well as responsibility for ineffective mitigation of it; (2) responsibility dependence on PQ assessment methodology; (3) responsibility for malfunctioning or misfunctioning equipment. At the moment, attribution of legal liability for problems caused by PQ is not widely applied practice due to unfulfilled prerequisites, but individual cases sometimes take place. First, in the field of PQ, attribution of liability is not possible without a fully functioning PQ monitoring system and data analysis skills. Since it is not feasible or cost-effective to monitor every busbar in the grid, research on the propagation of PQ phenomena (including its partial case--identification of the pollution source side) plays a very important role by enabling the prediction of PQ propagation paths [1; 2]. In addition to the already mentioned wind and solar parks, there are many other PQ polluters, including variable-speed drives, electric arc furnaces, welding equipment, both AC and DC electrified railways, etc., and each network or device can potentially become a PQ polluter at least due to the unavoidable risk of short circuits. Next, attribution of liability requires fair and transparent legal framework. PQ legislation is mainly composed of standards and, in general, their application is not mandatory (i.e., is voluntary) unless they are mentioned in either national or international legal documents [1]. Harmonized standards have a slightly higher importance: this specific category of European standards can be used to demonstrate that products, services, or processes comply with mandatory technical requirements given in European Union legislation, but their application is also usually voluntary, thus another way can also be chosen to achieve the goal. To begin with, currently, it is not always possible to apply the PQ legislation due to undetermined limit values. In addition, regardless of the juridical side, the engineering question also arises of when (what) situation is good (acceptable) and when is not. Usually, it is possible to identify the fact of pollution due to a clear PQ definition, but this does not mean a complete quantitative assessment. A considerable amount of research and discussions is still needed in order to sensibly determine permissible limits for the quantity of PQ events and other necessary norms. A brief summary of the current situation is provided below:  
* EN 50160:2010 sets requirements for supply voltage and frequency in normal operation mode, flicker severity, voltage harmonics (up to the 25 th, but some levels are still under consideration), voltage unbalance (only negative sequence magnitude), and mains signaling voltage (up to 100 kHz) in public electricity networks with nominal voltages up to and including 150 kV. Limits for rapid voltage changes, voltage sags, voltage swells, supply interruptions, voltage transients, and inter-harmonics are not set. The standard has many gaps which hinder the development of both artificial intelligence (AI) algorithms for PQ assessment and legal acts--some of them are already discussed in [8]. In Lithuania, as in most European countries, this standard is mentioned in the national legal acts and thus is mandatory. In accordance with the Rules for the Supply and Use of Electricity of the Republic of Lithuania [83], the operator, failing to ensure PQ in accordance with EN 50160:2010, must compensate the consumer for the damage caused, excluding the cases of natural phenomena (flood, thunderstorm, frost, sleet, storm, squall, hail, etc. ), fire, war, terrorist attack, force majeure, state action, third party action, activation of accident prevention automation, circumstances of necessary action, and many other cases related to the actions or inactions of the electricity consumers.