# Analysis of Plasma Reactor Interaction with the Power Grid Depending on the Power Supply Design
## 1 Introduction  
Plasma is used in a number of technological processes, including cutting, sputtering of coatings, gas and surface decontamination, production of carbon nanotubes, and melting of steel. The parameters of the technological process dictate use of plasma. For technical purposes, low-temperature plasma is produced in devices called plasma reactors, of which there are many designs [1; 2; 3; 4; 5]. The predominant method of plasma generation in these devices is electrical discharge in a gas. Occasionally, microwave, laser, induction or capacitive plasma generators are encountered. The possibilities for modifying plasma parameters in plasma reactors are limited [6; 7; 8]. It is possible to modify the discharge parameters by: (1) changing the shape of the electrodes, (2) changing the distance between the electrodes, (3) choosing the material from which the electrodes are made, and/or (4) choosing the shape of the discharge chamber. These methods often involve redesigning the plasma reactor and making changes to it or building a new reactor. Additional possibilities for shaping the plasma parameters are provided by the plasma reactor's gas supply system. By: (1) controlling the inflow of plasma-generating gas, (2) selecting the chemical composition of the plasma-generating gas, and/or (3) changing the gas pressure in the discharge chamber [9; 10; 11], plasma parameters can be easily and continuously influenced. In the main, it is the power supply system that determines the plasma parameters and the application possibilities of the plasma reactor [12; 13; 14]. Shaping the plasma parameters is possible through: (1) selecting the voltage between DC and AC, (2) selecting the frequency of the supply voltage, (3) selecting the voltage value, (4) selecting the voltage shape, (5) selecting the current value, and (6) influencing the harmonic content of the voltage and current. A power supply system that would allow the regulation of all these parameterswould have a complex design, which would translate into high manufacturing costs, high failure rates, high troubleshooting costs, susceptibility to interference, and complex operation. In most processes in which plasma reactors are used, extensive adjustment of the power supply parameters is not required. With a well-recognised and repeatable plasma process, it is possible to design a power supply that does not require any adjustment. Low manufacturing costs, low failure rates and simple operation are the most appreciated features of plasma reactor power supplies. The design of the power supply system determines the correct operation of the plasma reactor, its interaction with the power supply grid, and its impact on other equipment and people. The selection of the power system is not simple, since plasma reactors are strongly non-linear loads with stochastically varying parameters. Plasma reactors generate strongly electromagnetic interference, significant overvoltage and a large number of higher harmonics in the voltage and current [15; 16; 17]. Due to their low arc resistance, plasma reactors strongly loading the power systems [18; 19]. Due to the structural diversity of plasma reactors, even within a single reactor type, and the variety of plasma processes carried out with them, it is difficult to rank these devices in terms of technical parameters. As a result, there are no guidelines for designing power systems for the entire multitude of plasma reactors. Plasma generation by electrical discharge requires careful selection of the power supply system topology, its operating characteristics, and values of currents, voltages and frequencies [20; 21]. In order to obtain good operation and control characteristics of a plasma reactor, specialised power supply systems, individually designed for a specific reactor and a specific plasma process, should be used [22; 23]. From an operational, engineering and economic point of view, such an approach is unfavourable.