DAMAGE AND DIAGNOSIS OF POWER TRANSFORMERS OF PHOTOVOLTAIC PLANTS

The damage to the equipment of photovoltaic plants (PHS) was studied. The main attention is paid to oil-filled transformers with a voltage of 10/.0.4 kV, 35/.0.4 kV, 35/10/.0.4 kV with a capacity of up to 5 MVA and the development of an algorithm for determining probable places of damage to photovoltaic modules, which allows you to choose diagnostic equipment. The use of such equipment will ensure the detection of damage to power transformers and photovoltaic modules at an early stage of their development, as well as timely measures aimed at preventive repairs, reduce the number of transformer damages, downtime and repair of damaged power transformers that were damaged during their operation on FES. Operation of power transformers at photovoltaic plants involves their frequent switching on and off. High-voltage vacuum switches designed for a voltage of 10 kV or 35 kV are used as high-voltage switching devices. The capacity of inverters, the inductance of the windings of power transformers, the inductance of the windings of measuring voltage transformers, the capacity of cable lines and inserts under the conditions of using vacuum switches create prerequisites for the occurrence of commutation overvoltages, the occurrence of resonances in circuits (power transformer, cable insert or cable line, measuring voltage transformer). Increased thunderstorm activity is observed in the places of operation of some photovoltaic plants. The electrical equipment of these stations is affected not only by switching (internal overvoltages), but also by atmospheric overvoltages. To protect against overvoltages, arresters (type RVO, RVS, etc.) and overvoltage limiters are used. The damage of these surge arresters and limiters indicates the existence and intensity of overvoltages. Damage to cable inserts and cable couplings, voltage measuring transformers at photovoltaic stations and in electrical networks near these stations also testify to the negative impact of overvoltages on the FES equipment, including power transformers of these stations.