Yan Cheng Liu

Underwater GPS Positioning System Based on a Dual Acoustic Device

In order to solve the problem that existing underwater GPS positioning technology can only realize positioning underwater target installing acoustic transponder, the underwater target positioning system having good dependability with ultra-short baseline (USBL), forward looking sonar (FLS) and GPS receiver was designed. Using the system to position presetting underwater target in the offshore area of Dalian, positioning accuracy reached 1.2m, according with theoretical derivation, and verifying the feasibility using the system to obtain the latitude and longitude of underwater target in WGS-84 coordinate system.

Control for Grid Connected Inverter under Unbalanced Grid Voltage Based on PI-QR Controller

Control strategy under unbalanced and distorted grid voltage is one of the most significant tasks for grid-connected inverter (GCI). In order to guarantee that the grid current meets the related IEEE Std.929-2000, a new control scheme was presented. Firstly, the typical model of GCI was presented. Secondly, the GCI control model based on PI-QR controller in synchronous reference frame (SRF) was built. Finally, the system’s simulation was conducted under distorted and unbalanced grid voltage. The results demonstrate the effectiveness of the presented control strategy.

Shipboard Power System Restoration Using S-Curve Inertia Weight Particle Swarm Optimization

The shipboard power system (SPS) supplies energy to sophisticated systems for weapons, communications, navigation and operation. It is critical for the system to be reconfigurable for the purpose of survivability and reliability. The present paper proposes a new variation of PSO model for restoration of shipboard power system. A new inertia weight of S-Curve Decreasing variation is introduced. Particle Swarm Optimization with S-Curve Decreasing Inertia Weight (SDW-PSO) approach can improve the speed of convergence as well as fine tune the search. The proposed Particle Swarm Optimization algorithm enables to find the optimal combination of loads that can be supplied after the occurrence of the fault, in which the priorities of the loads and the constraint of balance between the total load and total generation are considered.

A Novel Algorithm to Improve Network Lifetime of Wireless Sensor Networks

One approach to extend the network lifetime is to divide the deployed sensors into disjoint subsets of sensors, or sensor covers, such that each sensor cover can cover all targets and work by turns. The more sensor covers can be found, the longer sensor network lifetime can be prolonged.This study propose a novel hybrid genetic algorithm (NHGA) comprising both basic generic operations with a fitness-improving local-search strategy to divide all wireless sensor nodes into a maximum number of disjoint set covers (DSCs). The simulation results show that NHGA outperforms the existing methods by generating more disjoint set covers and prolongs network lifetime.

Research on the Dynamic Characteristics of Switching Power Supply

In the fields of using green energy such as PV system and Wind power system, the step-up DC-DC converter, witch is used to convert the power, is now attracting more and more attention. The response characteristics and stability of one are key points for the performance of the whole system. However, it is complex to analyze the dynamic characteristics and control design. In this paper, the dynamic model of full-bridge DC-DC converter is presented, and transfer functions of the converter are derived by using state-space averaging method. And then the improved PI controller is designed. Finally, a laboratory prototype circuit with input voltage 220V, output voltage 600V is implemented and results are shown to confirm the validity of the designed switching device.

Marine Asynchronous Propulsion Motor Parameter Identification Using Dynamic Particle Swarm Optimization

This paper proposes a new application of dynamic particle swarm optimization (PSO) algorithm for parameter identification of vector controlled asynchronous propulsion motor (APM) in electric propulsion ship. The dynamic PSO modifies the inertia weight, learning coefficients and two independent random sequences which affect the convergence capability and solution quality, in order to improve the performance of the standard PSO algorithm. The standard PSO and dynamic PSO algorithms use measurements of the mt-axis currents, voltages of APM as the inputs to parameter identification system. The experimental results obtained compare the identified parameters with the actual parameters. There is also a comparison of the solution quality between standard PSO and dynamic PSO algorithms. The results demonstrate that the dynamic PSO algorithm is better than standard PSO algorithm for APM parameter identification. Dynamic PSO algorithm can improve the performance of ship propulsion motor under abrupt load variation.

Reconfiguration of the Shipboard Power System Based on Particle Swarm Optimization with Non-Clique Topology

The modern shipboard power system integrates heavy loads and has less fault tolerance than the terrestrial power system. Therefore, a fast and high-performance reconfiguration is needed when a fault occurs. This paper proposes a method to achieve a rapid and optimal reconfiguration for shipboard power system. This method at first employs graph theory to generate the topology of particles, which can construct a non-Clique topology. Then, the particle swarm optimization algorithm with the non-Clique topology is used to improve the restoration scheme while considering constraints. The proposed Particle Swarm Optimization algorithm enables to find the optimal combination of loads that can be supplied after the occurrence of the fault.

The Residual Life of Shipboard Cable Forecasting Based on PSO and GM(1, 1)

In this paper, the Gray Theory is used to predict the residual life of shipboard cable. However, under the influence of multi-factors, the grayscale of the model will be enlarged, which will influence the accuracy of the prediction. Therefore, the optimized parameter of the GM (1, 1) model based on PSO, is introduced to improve the precision of the predication. The method is proved effectively by the experimental data and the Arrhenius Equation.

TTSP-Based Study on Residual Life Prediction of Shipboard Cable

In this paper, TTSP is used to demonstrate that the aging characteristic quantity at high temperature accords with that at low temperature, and to predict the residual life of shipboard cable. The aging process of cable is described based on second order dynamic model. The method is proved effective by the experimental data, and provides theoretical bases for residual life of cable and cable anti-aging study under the influence of multi-factors.

A Comparison between Vector Control and Direct Torque Control for the Marine PMSM

In this paper the implementation of the vector control and direct torque control systems for a marine permanent magnet synchronous motor has been studied. A novel control method using space vector pulse width modulation was proposed. Then the simulation models with the vector control and direct torque control using the space vector pulse width modulation method have been established, respectively. Finally, the speed control performance of the systems was verified by simulation. The simulation results indicates that the systems used vector control or direct torque control technique can meet the requirements with the aspect of marine PMSM dynamic torque response. Meanwhile comparing to the different simulation results, the torque ripple was reduced in the vector control system.