RT-LAB Real-time Simulation Platform Research Articles

Combinatorial Multi-Objective Optimization of SFCL and SMES for the Low-Voltage Ride-Through Fulfillment of Solid-State Transformer

To figure out the low-voltage ride-through (LVRT) problem of a solid-state transformer (SST), this paper proposes a methodology that combinatorically optimizes a resistive superconducting fault current limiter (SFCL) and a superconducting magnetic energy storage (SMES) unit. The goal of minimizing the capacities of the resistive SFCL and the SMES while achieving the LVRT of the SST is designed, and a multi-objective Pareto optimization is carried out. Firstly, the modeling of a three-stage SST with a resistive SFCL and a SMES is presented through theoretical analysis, and the SST's fault transient characteristics are analyzed. Then, the optimization scheme based on the improved non-dominated sorting genetic algorithm-II (NSGA-II) is elaborated. The proposed approach is verified in a typical SST connecting a 10 kV power distribution network and a 380 V electricity grid. Using MATLAB/Simulink and RT-lab real-time simulation platform, different tests are done to check the rationality of the optimal solutions. The results reveal that a satisfying LVRT for the SST is guaranteed while minimizing the ratings of the SFCL and the SMES, and getting a proper reactive current injection. Consequently, the validity and suitableness of the proposed approach are well confirmed.

Real-time simulation method of MVDC integrated power system based on heuristic partitioning method and terminal resistance decoupling interface

In the process of real-time simulation of MVDC integrated power system, the traditional system partitioning method is low in efficiency, poor in the stability of decoupling interface, and unsatisfactory in use. In order to solve these problems, a complete set of real-time simulation method is proposed in this paper. The method involves a heuristic system partitioning scheme for the average distribution of switches and the smallest number of subsystems which is obtained by balancing the computational amount and combining the adjacent subsystems, a real-time simulation decoupling interface design method based on the terminal resistance for the purpose of dealing with the poor stability of the traditional ideal transformer interface, and a way to get values of the terminal resistance under the constraints of decoupling stability and accurate calculation. Then, a real-time model of MVDC integrated power system is established. And the proposed real-time simulation method is shown to be of high efficiency and stability on the Rt-lab real-time simulation platform. Compared with the traditional methods, it can greatly improve the accuracy of simulation.

Research on a Multi-Motor Coordinated Control Strategy Based on Fuzzy Ring Network Control

Aiming at the multi-motor coordinated control of intelligent robots, cross-coupling ring control based on fuzzy theory (CRCF) is proposed. Each motor is cross-coupled with two adjacent motors to form a multi-motor ring network structure that eliminates lag in speed tracking between motors and enhances synchronization between motors. Applying fuzzy control to the cross-coupling control of the proposed control strategy, the speed error and change in speed error of two adjacent motors are used as the input of the fuzzy controller, and its output is used as the input of the second of the two adjacent motors. The fuzzy controller achieves real-time tracking adjustment of the speed error between motors. The controllability and observability of the proposed control strategy are verified by the theorem of the Kalman matrix rank criterion. The external stability and internal stability are verified using an impulse response matrix. The theoretical analysis of the lag is verified by establishing a physical and mathematical model. Finally, a four-motor coordination control system model is built. By comparison with the non-ring network proportional cross-coupling control method, the effectiveness of the proposed control strategy is experimentally verified by the MATLAB/Simulink and the RT-LAB real-time simulation platform.

Real-time Simulation of Turboprop Engine Control System

AbstractOn account of the complexity of turboprop engine control system, real-time simulation is the technology, under the prerequisite of maintaining real-time, to effectively reduce development cost, shorten development cycle and avert testing risks. The paper takes RT-LAB as a platform and studies the real-time digital simulation of turboprop engine control system. The architecture, work principles and external interfaces of RT-LAB real-time simulation platform are introduced firstly. Then based on a turboprop engine model, the control laws of propeller control loop and fuel control loop are studied. From that and on the basis of Matlab/Simulink, an integrated controller is designed which can realize the entire process control of the engine from start-up to maximum power till stop. At the end, on the basis of RT-LAB platform, the real-time digital simulation of the designed control system is studied, different regulating plans are tried and more ideal control effects have been obtained.

Real-Time Simulation and Research on Photovoltaic Power System based on RT-LAB

The maximum power point tracking (MPPT) controller in the Photovoltaic system is the key to verify all kinds of MPPT control algorithms. But the development of actual controller has the defects of needing long periods, artificial code writing and so on. RT-LAB real-time simulation platform is an advanced model-based engineering design and test application platform. The outstanding real-time performance in the current experimental study and engineering design made it used more and more widely. Therefore, it is necessary to introduce its hardware and software structure and realtime performance in detail. This paper gave a comprehensive and systematic introduction to hardware architecture, software architecture and simulation process of RT-LAB. It also presented a semi-physical simulation experiment of photovoltaic system MPPT using the features of Photovoltaic MPPT and semi-physical Real-Time simulation technology. The MPPT control strategy is achieved by establishing model using Simulink package. Other parts of the main circuit were physical circuit except controller. The parameter adjustment functions of online RT-LAB can easily optimize controller parameters. Two special tools, ARTEMIS and RT-Events used in power electronics were described in detail. The RT-LAB software modeling standard was also illustrated. The testing results showed that the usage of RT-LAB for the development of photovoltaic controller can resolve many problems in the current controller development. The application of RT-LAB in photovoltaic systems provides a reference for the micro grid, smart grid and other real-time systems.

Energy storage system-based power control for grid-connected wind power farm

Wind power is characterized as intermittent with stochastic fluctuations, which can result in deviation of grid frequency and voltage when the wind power ratio is high enough. These effects have a definite impact on stability and power quality of grid operation. This paper proposes an energy storage system (ESS) based power control for a grid-connected wind power system to improve power quality and stability of the power system. Vanadium redox flow battery (VRB), as an environmentally-friendly battery provided with many advantages, is employed in the ESS. A dynamic mathematical model of VRB is built by using an equivalent circuit, and its charging and discharging characteristics are analyzed. The VRB’s stable voltage is available in a wide range (around 20–80% state of charge), which is suitable for utilization of a single-stage AC/DC converter in the VRB-based ESS. With a proposed energy storage control method, VRB-based ESS is added at the exit of the grid-connected wind farm to filter fluctuations of wind power, which ensures that smooth power will be injected into the grid and which improves power quality of the power system. Simulations and experiments are carried out to verify the proposed power control method for these grid-connected wind power systems. The grid-connected wind farm with VRB-based ESS, wind speed (characterized as gust and stochastic wind), and wind turbines are modeled in simulations. Simulation results show that the grid-injected active power from the wind farm is effectively smoothed, and reactive power support can be provided for the grid by the designed VRB-based ESS. Experimental verification is achieved with a low power bench, where a RT-LAB real-time simulation platform and a direct torque controlled induction motor simulate a real wind turbine and a wind speed model is built in the RT-LAB real-time simulation platform. The experimental results verify the proposed scheme through demonstrating a stable and smooth power flow injected into the grid though the wind power fluctuated.

FPGA-based Ultra-Low Latency HIL Fault Testing of a Permanent Magnet Motor Drive using RT-LAB-XSG

Presented is a real-time simulator of a permanent magnet synchronous motor (PMSM) drive implemented on an FPGA card. Real-time simulation of PMSM drives enables thorough testing of control strategies and software protection routines and therefore allows rapid deployment of vehicular or industrial applications. The proposed PMSM model is a phase domain model with sinusoidal flux induction. A 3-phase IGBT inverter drives the PMSM machine. Both models are implemented on an FPGA chip, without any VHDL coding, with the RT-LAB real-time simulation platform of Opal-RT Technologies using a Simulink blockset called Xilinx System Generator (XSG). The paper explains various aspects of the design of the motor drive models in fixed-point representation in XSG, as well as simulation validation against a standard PMSM drive model built in Simulink. The PMSM drive, along with a open-loop test source for the pulse width modulation, is coded for an FPGA card. The model has user-selectable dead time, modulation index, source angle offset, and frequency. The PMSM drive is completed with various encoder models (quadrature, Hall effects and resolver). The overall model compilation and simulation is entirely automated by RT-LAB. The drive can also run in a closed loop with a controller executing on a CPU of a real-time simulator. The phase-domain PMSM drive model runs with an equivalent 10 nanosecond time step (100 MHz FPGA card) and has a latency of 300 nanoseconds (PMSM machine and inverter). The motor drive is directly connected to digital inputs and analog outputs with 1 microsecond settling time on the FPGA card and has a resulting total hardware-in-the-loop latency of 1.3 microseconds.