Font Size: a A A

Research On Distributed Control Of New Energy Marine Power Systems

Posted on:2017-03-17Degree:MasterType:Thesis
Country:ChinaCandidate:T Y XiongFull Text:PDF
GTID:2272330509957487Subject:Control science and engineering
Abstract/Summary:PDF Full Text Request
With the advent of low-carbon economy, as an effective means of energy saving and emission reduction, the application of new energies in marine power systems has been an irresistible trend. New energy marine power system is such a power system whose electricity is jointly generated by new energy sources such as wind power and solar energy, wave energy. However, external disturbances and loads fluctuations can easily lead voltage and frequency in the new energy ship power system to be unstable, so the effective control strategy is of particular importance. Hierarchical control is applied in this subject to regulate the voltagies and frequencies in the system. Droop control is mainly adopted in the primary control to preliminarily regulate, aiming at the problem that the primary control may result in the deviations between the voltage amplitudes and frequencies and their reference values, so the secondary control is required to eliminate the deviations. Due to the distributed control’s advantages of low cost and high reliability, the secondary distributed cooperative control is mainly studied in the thesis.Firstly, the relevant theoretical knowledge is introduced in the thesis, including graph theory used to describe communication structure, stability theories of systems applied to verify the validity of the controllers, and the sliding mode structure control principle. All the knowledge has laid the foundation for the designing of the secondary distributed cooperative control algorithms.Secondly, the distributed cooperative control models of new energy marine power system are established. By adopting input output feedback linearization, the linear voltage and frequency models are established, and the distributed cooperative control algorithms of voltagies and frequencies in DGs are designed to make the voltagies and frequencies asymptotically converge to their references, at the same time, achieve the active power sharing. In addition, considering the uncertainty of the new energy marine power systems, voltage first-order nonlinear model is established, based on the neural network theory, the voltage adaptive control algorithm is designed to make the voltagies synchronize to the reference.Thirdly, in order to accelerate the convergence speed, the finite time distributed cooperative controllers are put forward. Adopting the model established by input output feedback linearization, and considering two situations of the fixed communication topology and switching topologies, finite time control algorithms for voltagies and frequencies are respectively designed to achieve the voltagies and frequencies’s convergence to their references in finite time and active power sharing in finete time. The asymptotically stability or finite time stability of the closed-loop systems are strictly proved by the stability theories, such as lyapunov stability theories, LaSalle invariant set principle and finite time stability theories, the validity and effectiveness of the proposed control algorithms are verified by the simulation results.Finally, the terminal sliding mode control is applied to achieve tracking synchronisation of the DG voltagies in finite time. As the improvement of the sliding mode variable structure, terminal sliding mode inherit its advantage of good robustness. Based on the first-order nonlinear voltage model, considering the dynamics of the low-pass filter, the second-order nonlinear voltage model is established. In view of the problem that applying linear sliding mode control is unable to converge in finite time, based on the traditional terminal sliding mode, the secondary voltage distributed cooperative control is put forward to realize the voltagies’s convergence in finite time. Considering the drawbacks of slow convergence speed and singularity of the traditional terminal sliding mode control, the fast terminal sliding mode and non-singular terminal sliding mode voltage distributed cooperative control strategies are proposed. All of the three kinds of algorithms are strictly proved in theory, the validity and effectiveness of the three algorithms are verified by the simulation results.
Keywords/Search Tags:distributed generator, secondary control, multi-agent system, distributed cooperative control
PDF Full Text Request
Related items