The dissertation is devoted to solving the scientific and technical problem of developing energy-based control systems for complex electrotechnical complexes in the direction of decomposing port-Hamiltonian (pH) systems that describe the operation of these complexes.
The increasing complexity of electrotechnical complexes complicates the mathematical description of such systems, and the nonlinearity of such systems causes a challenging task of synthesizing stable control systems for such objects. Therefore, from the perspective of electrical engineering and electromechanics tasks, it is relevant to study the possibility of applying decomposition to port-Hamiltonian (pH) systems that describe processes in electrotechnical complexes to simplify the subsequent synthesis of energy-shaping control systems (ESCS).
Аn analysis of literature sources on the topic of the work was carried out. A review of electrotechnical complexes and their components was made. The theoretical foundations of control systems based on energy approaches, their methodology, and the challenges related to synthesizing control systems for electrotechnical complexes were considered. An analysis of existing methods for decomposing complex nonlinear systems and their applicability to pH systems was carried out. The main objectives of the dissertation research were formulated.
А classification of prospective methods for decomposing pH systems describing the operation of electrotechnical complexes based on energy principles was conducted. These methods were divided into two groups: structural decomposition and mode decomposition. In turn, structural decomposition was divided into cascade, parallel, and combined types. The presented decomposition methods were analyzed, their implementation features were considered, and the advantages and disadvantages of each approach were substantiated. For each proposed method, an example of its application to an electrotechnical complex was provided, and the specifics of the subsequent synthesis of the ESCS was determined.
А structural decomposition was applied to the pH system of a complex autonomous electrotechnical complex that generates electricity from the renewable wind and solar sources and stores it in a hybrid battery-supercapacitor energy storage system. A seventh-order mathematical model was obtained for the general pH system of the complex and fifth- and second-order systems were obtained for three pH subsystems, into which the general system was decomposed. Structural syntheses of the ESCSs for the general and decomposed systems were carried out resulting in sets of control influence formers (CIF). In the MATLAB/Simulink environment, a computer modeling of the investigated complexes with synthesized ESCSs was performed, the best CIF structures were found, and their adaptive parametric syntheses were conducted. A comparative analysis of the operation of the ESCSs of the general and decomposed systems showed almost identical control quality, with a significant simplification of the synthesis process by approximately 46% due to the application of decomposition. A comparative analysis of the operation of the general and decomposed ESCSs systems was carried out, which showed almost the same quality of their control. Thus, in relation to the problem, the structural decomposition of the electric generator and the energy storage complex for the production of three ESCSs will allow reducing the number of independent interconnections and damping from 28 in the ESCSs in the entire complex to 15 in the largest of the ESCSs subsystems, into which the general pH is decomposed, which is 46% less.
A mode decomposition of the pH system of a vehicle electric drive based on a DC motor with a bidirectional Zeta-SEPIC DC-DC converter was applied. The Zeta DC-DC converter provided drive control in the traction mode, while the SEPIC DC-DC converter handled the braking mode. As a result of the mode decomposition, the pH subsystems were obtained for the respective modes, for which structural synthesis of the ESCS was implemented. At the same time, three levels of energy shaping were considered: the armature voltage, the armature current, and the angular velocity of the motor. For each of these cases, the parametric synthesis of the best CIFs was carried out, and their parameters were adapted to ensure the same level of system speed under different states. Computer modeling and simulation of the electric drive system in various operating modes were conducted, demonstrating the effectiveness of modal decomposition.
The verification of theoretical studies was conducted. A mock-up model of the drive system was constructed, and its components were examined: the battery module, DC-DC converter, and electromechanical complex. The ESCS for armature current of the motor was implemented based on a microcontroller using mode decomposition.
