1 st International Conference on Sustainable Materials, Manufacturing & Energy Technologies (SMMET 2022) June 24-25, 2022 Raj Kumar Goel Institute of Technology, Ghaziabad Page 865 “Fuzzy system and dq0 transformation for protection of power transformer " V. K. Sahu*, Y. Pahariya** *(Department of Electrical & Electronics, SOET, SUN, India Email: vijay25051991@gmail.com) ** (Department of Electrical & Electronics, SOET, SUN, India Email : yogesh.pahariya@sandipuniversity.edu.in) ABSTRACT The most important element of power system can be said is the power transformer. This important as well as essential element should have a continuous monitoring and also effective protection. For the protection of the power transformer number of methods are present. One of the common method is the differential logic as it can easily distinguish between normal operation and internal fault conditions. Some operating conditions of the power transformer have a significant effect on differential logic operation which also have effect on the stability of power system. The algorithm has been proposed to enhance the performance of protection used power transformer by using dq0 transformation and fuzzy system. MATLAB software was used to model a power system and to test the algorithm. Keywords - Differential protection, dq0 Transformation, Energization, Fuzzy logic system, Over-excitation. I. INTRODUCTION Power system is very important for the modern world as it absence can halt almost everything. So the protection of the same is very essential. Power transformer being an important equipment of power system, protection of the same is also essential to protect the power system eventually. Failure of power transformer protection can be interpreted as failure of the power system itself. Number of protection methods are available for the power transformer [1]. The basic technique used to protection the power transformer is percentage differential logic as shown in Fig. 1. The protection technique can differentiate between fault conditions and normal operation. Faults can be internal as well as external. But just by detecting the differential current shall not be enough so that it can differentiate between internal faults and certain operating situation which produce almost similar current. Operating condition which can produce similar current are over- excitation, magnetizing inrush current (energization current) and sympathetic inrush currents. These operating conditions can lead to abnormal tripping. So to develop a protection system which and distinguish between normal operation and mentioned operating situation is challenging. Many methods have been developed recently to protect the power transformer [1], [2]. Some methods to enhance the differential protection [3]- [11], are implemented for protection of power transformer. The wavelet transform [3]- [5] and other transforms [6], [7] are used for the protection purpose. Hybrid system as well as restraint methods were also used for the same purpose [2], [8]. To differentiate between magnetization current and internal fault is also required in transformer to improve reliability of the protection system designed [9]– [11]. Figure 1. Differential relay diagram. Dissolved Gas Analysis (DGA), a method in which the gas produced within the transformer is analyzed. This method has a limitation, the amount of gas produced depends om facto like loading, age of the transformer and even the thermal history of the transformer. Due to this reason no universally acceptable rules are available. Even with the limitation different methods are available with DGA [14]- [22]. A method for the protection of the transformer has been proposed using dq0 transformation and fuzzy system. Magnetizing inrush and over- excitation are considered so they don’t cause mis- Electronic copy available at: https://ssrn.com/abstract=4159622