I want to paraphrasse this text Introduction to Real-Time Simulation Real-time s

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I want to paraphrasse this text

Introduction to Real-Time Simulation

Real-time simulations are quite different from the well-known offline simulations in many aspects including execution time, constraints etc. In this Chapter, real-time simulations are discussed thoroughly addressing several points such as the constraints for a valid real-time simulation, the different modes of a real-time simulation and the available hardware to implement the real-time simulation. The application of real-time simulations in the field of power electronics will be the core of this thesis.

1.1.1 What is a Real-Time Simulation?

Software packages such as Matlab and Simulink are widely adopted to validate the performance of mathematical and theoretical models and modern designs of systems. Nevertheless, these packages run in non-real-time (or offline), which means that the computation time of the model can be much longer than the response time of the real system. This prevents the interface of external hardware, which restricts the use of these packages to only offline verification with no hardware involved in the process [1].

To be able to interface external hardware, the simulator must receive information from the external system and use it to compute the model outputs within the time-step of the simulation. In other words, the computation time of the model must be less than the simulation time-step. This is basically the definition of a real-time simulation. In simple words, the real-time simulator must produce the internal variables and outputs within the same length of time as its physical counterpart would as illustrated in Figure 1.1 [2]. With this condition satisfied (Tc < TS), a sound real-time simulation is achieved and the integration of external equipment with real-time simulators is possible. If the computations are not performed within the simulation time-step, the simulation is considered erroneous. In this case, one time-step is omitted and the simulator uses the following time-step to perform the next computation. This is referred to as an overrun.

1.1.2 Modes of Real-Time Simulation

Real-time simulators are used in three different modes: Rapid Control Prototyping (RCP), Hardware-in-the-loop (HIL), and Software-in-the-loop (SIL) [2]. Rapid control prototyping is where a digital controller is implemented in the real-time simulator and connected to a physical plant. Conversely, in HIL applications, a physical controller is tested against a virtual plant modelled on the real-time simulator. Finally, SIL is the combination of RCP and HIL simulations, where both the controller and the plant are running on the simulator.

HIL simulations are typically employed when testing a physical controller or a protection scheme, but the actual plant is either unavailable or not permissible for testing. Therefore, a virtual plant, which emulates the performance of the real system, is implemented on the real-time simulator allowing for safe and early testing of the controller/protection device. Moreover, many possible scenarios that could happen in a real system can be tested quickly, securely and without physical modifications. In power systems, utilities prohibit testing with the actual system. Therefore, a virtual plant which captures all attributes of the real system is developed on a real-time simulator, and the protection device is then incorporated with the simulator. Faults can be applied safely to the virtual plant to verify the functionality of the protection device. Another application of HIL simulations is in motor drives. In some cases, the power converter and the motor are not available at the time when the physical controller is developed. Therefore, a virtual plant consisting of the power converter and the motor is developed on the real-time simulator to save time and perform early testing of the drive. Furthermore, extreme conditions that would, in practice, damage a real motor can be investigated.

Explanation / Answer

Introduction to Real-Time Simulation

Generally these Real-time simulations are quite different from the offline simulations in many aspects including execution time

and contraints.Here we will discuss greatly addressing several points such as constraints for a real time simulation,different

modes,and the hardware available to implement the real-time simulation

What is Real-time Simulation

Generally these software packages like Matlab and simulink are adopted to validate the performance of mathematical,theoretical and modern

designs of system.However this packages run in offline mode which takes more computational time than real system.It also prevents the interface of external hardware which restrict the of these packages to only offline verification with no hardware involved in the process.

To be able to interface external hardware,the simulator must receive information from the external system and use it to compute the model output within which the computation time of the model must be less than the simulation time-step.If the simulation time-step is not performed within the time ,this simulation is considered erroneous,in that case time-step is omitted and the simulator uses the following time-step to perform the next computation. This is referred to as an overrun

Modes of Real-Time Simulation

They are used in 3 different modes

Rapid Control Prototyping(RCP):-In this a digital controller is implemented in real time simulator a connected to a physical plant

Hardware-in-the-loop (HIL):-In this a digital controller is tested against a virtual plante modelled on the real-time simulator

Software-in-the-loop (SIL) :- It is a combination of RCP and HIl where both the controller and plant are running on the simulator.

Generally this HIL simulations are used when testing a physical controller or a protection scheme,but the actual plant is either unavailable or not permissible for testing.For this reason a virtual plant, which increases the performance of the real system,is implemented on the real-time simulator for safe and early testing of the controller/protection device.In power systems,utilities prohibit testing with actual system,for this a virtual plant which contain all the attributes of real time system is developed on real-time simulator ,protection device is also incorporated with the simulator.Any faults or mistakes can be applied safely to the virtual plant to verify the functionality of the protection device.

Next application of HIL simulations is in motor drives. In some cases, the power converter and the motor are not available at the time when the physical controller is developed.For this a virtual plant consisting of the power converter and the motor is developed on the real-time simulator to save time and perform early testing of the drive. Besides extreme conditions that would, in practice, damage in a real motor can be investigated  

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