Simulation of protection against unbalanced high-voltage asynchronous drive of recycle compressor in fuel hydrotreating unit

Abstract

In the oil and gas industry, continuous processes such as oil and gas refining play a great role and are sensitive to many external factors. Such processes require special procedures for stopping and restarting. In order to maintain a sustainable process, the entire system needs to be cleaned by removing of unreacted components. Rejected raw materials are often dumped into a flare leading to tangible environmental problems and significant economic disadvantages. Electrotechnical systems (ETS) play an important role in ensuring continuous technological processes in oil and gas industry. Electric motors are one of the key elements of ETS. The majority of the electrical machines used in industry today are Asynchronous motors (AM) – no less than 80 %. Ensuring their trouble-free operation is one of the key factors in the design, simulation, and analysis of asynchronous motor relay protection systems, including unbalanced conditions of their operation. These conditions can occur due to unbalanced AM connection circuits, supply voltage unbalance, or as any faults in a machine itself. Operating a motor under these conditions will result in shorter motor life, reduced power, wear and aging of the insulation. The study subject was an Asynchronous motor drive of a recycle compressor of a gasoline hydrotreating unit at the fuel hydrotreating integrated unit at the Astrakhan Gas Refining Plant (AGRP). The authors used Matlab simulations to study the facility and its protection systems/devices operation. The method of symmetrical components was selected as the main theoretical method. The authors developed a model of an asynchronous motor drive of a recycle compressor. This involved establishing a set of relay protections (RP) and developing the models of the following protections: sequence filter (symmetrical component filter) (SF), negative sequence (nps) O/C protection, and overload protection. It was demonstrated that the specified relay protection complex fully protects the motor from unbalanced operation conditions. The authors conducted a study of the protection complex operation under different supply voltage unbalances, with different motor loads. They formed a conclusion about the performance of the developed protection complex, and gave recommendations for its technical implementation in a business environment. The study findings can be used as a basis for the development and testing of relay protection components of the entire electrical system of the fuel hydrotreating unit at the Astrakhan Gas Refining Plant.