Wind Turbine Doubly Fed Induction Generator (Phasor Type) is operated under phasor and energy storage is discrete, this is how to solve

Hello, everyone, do you know how to change the Wind Turbine Doubly Fed Induction Generator (Phasor Type) in simulink to discrete, because the system needs to add energy storage, energy storage a lot of things are discrete, two put together can not run, How to modify it? Is it a need to redo an energy storage system that can run on phasor? How should I do this? Are there any good people willing to help me

Answer 1

[Umar]

Hi @面 ,

After reviewing the Wind Turbine Doubly-Fed Induction Generator (Phasor Type) documentation provided at the link below

https://www.mathworks.com/help/sps/powersys/ref/windturbinedoublyfedinductiongeneratorphasortype.html

You have to understand the current model since the existing phasor-type model uses continuous-time dynamics based on the principles of power flow and control systems for DFIGs. It employs Voltage-Sourced Converters (VSCs) for rotor and grid-side conversions, which are designed for steady-state analysis. So, in order to perform discrete time conversion, my suggestion would be replacing continuous blocks with discrete equivalents. In Simulink, this often involves using blocks from the “Discrete” library such as Discrete-Time Integrators or Zero-Order Hold blocks.

Please click the link below to understand how to utilize these blocks in Simulink

Zero order block

https://www.mathworks.com/help/simulink/slref/zeroorderhold.html?searchHighlight=zero%20order%20hold%20block&s_tid=srchtitle_support_results_1_zero%20order%20hold%20block

Discrete time integrator block

https://www.mathworks.com/help/simulink/slref/discretetimeintegrator.html?searchHighlight=Discrete-Time%20Integrator%20block&s_tid=srchtitle_support_results_1_Discrete-Time%20Integrator%20block

Afterwards, set an appropriate sample time for your discrete system. This will define how frequently your model updates its calculations, which is crucial for stability and performance. Modify the control loops (like PI controllers) to operate in discrete mode. This usually involves transforming continuous gains into discrete gains using methods such as Tustin’s method or matched pole-zero transformations.

Now, to integrate energy storage, I would suggest creating or selecting a discrete energy storage model that suits your needs (e.g., battery, supercapacitor). Make sure it has inputs and outputs compatible with your DFIG model. Use appropriate signal routing techniques (e.g., bus selectors) to connect outputs from the DFIG (like power output) to inputs on the energy storage system. Then, implement control strategies that manage power flow between the DFIG and energy storage effectively. This may involve logic to determine when to store excess energy or release stored energy based on grid demand or operational conditions. After modifications, simulate the model under various conditions to ensure it behaves as expected. Pay particular attention to transient responses and steady-state performance and compare results with expected outcomes from the original phasor model to identify discrepancies that may arise due to discretization.

I would also suggest to refer you back to relevant sections of Simulink documentation specific to your components (e.g., DFIG, energy storage) for detailed guidance on parameters and operational modes. Make sure to utilize examples provided within Simulink that demonstrate similar setups, especially those focusing on renewable integration with storage systems and establish performance metrics (e.g., efficiency, response time) that are critical for your application. These can guide further refinements in your model.

By following structured modifications mentioned above, validating through simulations, and leveraging resources available in Simulink documentation, you should be able to achieve a functional integration that meets your project requirements. If you need more specific details on any step or component configuration, feel free to ask!

[面]

Hello, I am honored that you can answer my questions and give me some inspiration, but I still have some questions I would like to ask you. Do you mean to discretize continuous modules in DFIG? Does this allow the fan operating under phasor to be converted to operating under discrete? However, since there are too many contents in the DFIG module of simulink after it is expanded, I am not quite sure which part to modify. Could you please give me a detailed explanation and give me examples to explain what contents to modify? In addition, is it possible to build an energy storage that can run under phasor and connect it with the fan? This problem has been bothering me for a long time and I have been unable to find a solution. I would be very grateful if you could guide me, thank you very much!

[面]

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[面]

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[Umar]

Hi @面,

You mentioned, “Do you mean to discretize continuous modules in DFIG? Does this allow the fan operating under phasor to be converted to operating under discrete? However, since there are too many contents in the DFIG module of simulink after it is expanded, I am not quite sure which part to modify. Could you please give me a detailed explanation and give me examples to explain what contents to modify? In addition, is it possible to build an energy storage that can run under phasor and connect it with the fan? This problem has been bothering me for a long time and I have been unable to find a solution”

Please see my response to your comments below.

I did briefly review your Simulink diagram. You did a commendable job. Now, in order to discretize continuous modules in a DFIG model in Simulink is a multifaceted task, it requires a thorough understanding of both the DFIG system and the discretization process. You probably have to design a separate simulink model based on my detailed explanation of how to approach this task, including specific modifications to the DFIG module and examples based on the signal group names and types provided in the links above that I shared with you in my earlier comments.

Step 1: Understanding the DFIG Model

The DFIG model in Simulink consists of various components that simulate the behavior of the generator under different operating conditions. The inputs and outputs you listed are crucial for understanding how the system operates. The key inputs include:

• A, B, C: The three terminals of the DFIG.
• Trip: A logical signal for disconnecting the DFIG.
• Wind (m/s): The wind speed input.
• Tm: Mechanical torque input.
• Vref: External voltage reference.
• Qref: Reactive power reference.
• Iq_ref: Reactive current reference.

The outputs include a variety of phasor signals, such as currents and voltages in both the stator and rotor, as well as power outputs.

Step 2: Discretization Process

To discretize the continuous modules, you will need to replace continuous blocks with their discrete counterparts. This typically involves the following steps:

1. Identify Continuous Blocks: Open the DFIG model and identify blocks that are operating in continuous time (e.g., integrators, continuous transfer functions).

2. Replace with Discrete Blocks: Replace these blocks with discrete equivalents. For example, use the "Zero-Order Hold" block to convert continuous signals to discrete signals. You can also use the "Discrete Transfer Function" block for any transfer functions.

3. Set Sample Time: Ensure that you set an appropriate sample time for the discrete blocks. This is crucial for maintaining the stability and performance of the system.

4. Modify Signal Routing: Adjust the signal routing to accommodate the new discrete signals. This may involve using "Bus Selector" blocks to extract specific signals from the output vector m.

Example Modifications

Here are specific modifications based on the signal group names and types:

• Phasor Currents (Iabc): If you are using a continuous current measurement block, replace it with a discrete measurement block. For instance, if you have a continuous current sensor, use a "Discrete-Time Integrator" to sample the current at the specified sample time.

• Voltage Signals (Vabc): Similar to the current signals, replace any continuous voltage measurement blocks with discrete equivalents. Use a "Zero-Order Hold" block to sample the voltage signals.

• Mechanical Torque (Tm): If the mechanical torque is being applied continuously, ensure that it is sampled at the same rate as the other signals. Use a "Unit Delay" block to maintain the discrete nature of the signal.

Step 3: Integrating Energy Storage

To build an energy storage system that operates under phasor conditions and connects with the fan, follow these steps:

1. Define Energy Storage Parameters: Determine the specifications of your energy storage system (e.g., battery, supercapacitor) and its control strategy.

2. Create a Subsystem: In Simulink, create a new subsystem for the energy storage system. This subsystem should include blocks for energy storage dynamics, control logic, and interfacing with the DFIG.

3. Connect Inputs and Outputs: Use the outputs from the DFIG (e.g., P, Q, Vdc) as inputs to your energy storage subsystem. You can use these signals to control the charging and discharging of the energy storage system.

4. Control Logic: Implement control logic within the energy storage subsystem to manage the flow of energy based on the DFIG's output. This could involve using a PID controller or other control strategies to optimize performance.

Hope, this helps.