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Wind energy conversion systems (WECS) harness the power from the wind to generate electricity. This is a renewable energy source which is gaining popularity worldwide due to its low environmental impact and potential to reduce carbon emissions. A wind energy conversion system typically consists of a wind turbine, a generator, and other components such as power electronic systems.

Fig 1. Wind Energy Conversion Systems (WECS)

At the core of the turbine, which consists of blades attached to a rotor. As the wind blows, the blades capture the wind's energy and cause the rotor to spin. This rotational motion is then transferred to the generator, which converts the mechanical energy into electrical energy. The generator can be of different types, such as synchronous or asynchronous, depending on the design and application.

The electrical energy produced by the generator is then conditioned and converted to match the voltage and frequency of the power grid. Power electronics play a vital role in this process by ensuring efficient energy transfer. Additionally, transformers might be used to step up the voltage for long distance transmissions.

There are essentially two types of WECS: one-shore and off-shore; while both harness the energy from the wind to generate power, there are some notable differences in terms of location, design considerations, and challenges.

On-shore WECS are located on land and are often situated in open areas with consistent winds. These systems are easier to install and maintain due to their proximity to existing infrastructure and logistical networks. On-shore wind farms can vary in size, from small community installations to large-scale wind farms with multiple turbines. They are typically less expensive to construct and operate compared to their off-shore counterparts.


Real-time WECS emulation is essential for testing and validating wind energy technology under realistic conditions without the risks or costs associated with field testing. By creating simulation models of a wind turbine and its environment, we can emulate various scenarios such as changes in wind speed, turbine performance, and grid interactions in real-time. This allows for detailed assessment of turbines and control strategies in a controlled lab environment.

Emulation can replicate real-world scenarios within your laboratory environment. By emulating different grid conditions and load scenarios, we can evaluate how WECS respond to dynamic operating conditions and optimize their control strategies accordingly.

Moreover, real-time emulation helps identify potential issues and improves system reliability and safety. By testing different operating conditions, we can fine-tune performance and ensure the WECS operates efficiently and effectively. Emulation also supports the development of different control algorithms for power electronics for integration of wind energy into the power grid.

In conclusion, WECS emulation is a method for ensuring the reliability, resilience, and performance of your WECS and microgrid systems. By rigorously testing and emulating WECS components and systems, we can optimize their design, validate their performance. For a sustainable future, WECS testing, and emulation will play a vital role in shaping the reliability and resilience of our energy infrastructure.


Let us now see how a WECS is modeled in Simulink.

Fig 2. On-shore vs Off-shore Wind power plants


Wind Turbine Model:

The wind turbine model uses a permanent magnet synchronous generator (PMSG), a turbine rotor, and a pitch-angle controller to study and understand the dynamics and performance of wind energy systems. These models replicate the behavior of real wind turbines, providing insights into their operation and allowing for testing and optimization.

The model begins with the turbine rotor, which captures the kinetic energy of the wind and converts it into mechanical energy. The turbine's performance depends on factors such as wind speed. The pitch-angle controller plays a key role in optimizing the turbine's power output by adjusting the angle of the turbine blades; this controls the rotor speed and regulate power output for optimal performance.

Fig 4. Simulink BESS Model

The mechanical energy from the turbine rotor is then transferred to the permanent magnet synchronous generator (PMSG), which converts it into electrical power. The electrical energy produced can be conditioned and controlled using power electronics to match the requirements of the power grid.

AC/DC Rectifier and Inverter Models:

For the WECS emulation, the AC/DC rectifier model employs the Universal Bridge block from Simulink, combined with a current dq control technique for rotor-side control to effectively convert the three-phase AC power generated by the wind turbine's permanent magnet synchronous generator (PMSG) into stable DC power.

Fig 5. Rectifier and Inverter Models

Grid Model:

Here, we seek to replicate the behavior of various components like generators, loads, and transmission lines. At the core of grid modeling lies the "3-Phase Programmable Voltage Source" block, a Simulink component that allows us to define the characteristics of the voltage source of the grid. By configuring parameters such as voltage magnitude, frequency, and phase angle, we can emulate diverse grid conditions, ranging from nominal operation to fault scenarios. Integration of the "3-Phase Programmable Voltage Source" along with series impedances blocks within Simulink provides us a good platform for simulating and analyzing grid behavior.

Fig 6. Simulink Grid Model


Fig 7. Impedyme’s CHP Cabinet

The Impedyme’s emulation solutions mimic your MATLAB Simulink models that can be used for high power tests, up to a few Mega Watts scale, for bandwidths up to 20 kHz. Simply connect the optical links to our cabinets and deploy your models to begin the testing. The cabinets have multiple optical links each up to 12.5 giga-bits per second. For simulations with ultra-low step-times, the equipment supports FPGA-based tests, that allows you to have time steps as low as a few nanoseconds. Moreover, the FPGA brings in a better performance for your real-time emulation since the processing speed of an FPGA is much higher than that of a CPU.

Also, for high-speed emulations, the individual FPGAs of the drawers can communicate among them. The testing using Impedyme’s CHP is straightforward as it uses Simulink designs. Our products come with a wide range of pre-designed models, which you can customize the designs according to your needs and requirements. Furthermore, if we were to emulate both the input and the output side of the power systems, we can have a circulating power flow. Since the power is recirculated, we only must feed in power losses from the grid. By having such a technology can reduce the power requirements of your lab for testing large power systems. Moreover, during the real-time emulation of your models, our integrated thermal management utilizes an advanced liquid + air cooling technology that ensures that does not require any additional chiller for cooling. Thus, we use Impedyme’s CHP to emulate the developed WECS model in real-time. 

Now that we have developed the grid-connected WECS model, let us see how the connections are given to kickstart the testing process.

Fig 3. Simulink Model of WECS

The use of current dq control for rotor-side control optimizes the performance of the wind power system. This technique involved transforming the three-phase currents from the generator into direct and quadrature (dq) components and transformation equations. By regulating the dq currents, we can control the power flow and maintain stable operation under different wind conditions. Building on the AC/DC rectifier model for wind turbine emulation, inverter model is incorporated that uses the Universal Bridge block from Simulink for the DC/AC conversion.

This model, combined with a current dq control technique for grid-side control, enables to integrate the generated power with the grid. The Universal Bridge block allows a conversion from DC (from the rectifier model) back into three-phase AC power, making it suitable for grid connection. This process ensures that the energy produced by the wind turbine can be used in conjunction with the grid. The current dq control, by transforming the AC currents into direct and quadrature (dq) components using a phase-locked loop (PLL) and transformation equations, we could regulate the power flow and maintain synchronization with the grid frequency and voltage. This control method improvs the power quality and ensures stable operation.



1.  J. -Y. Ruan et al., "Transient Stability of Wind Turbine Adopting a Generic Model of DFIG and Singularity-Induced Instability of Generators/Units With Power–Electronic Interface," in IEEE Transactions on Energy Conversion, vol. 30, no. 3, pp. 1069-1080, Sept. 2015, doi: 10.1109/TEC.2015.2423689.

CHP seamlessly integrates hardware-in-the-loop (HIL) and power hardware-in-the-loop (PHIL) capabilities, offering unparalleled accuracy and efficiency in WECS development and designs. With CHP, engineers can simulate real-world scenarios with precision, testing grid connected WECS under dynamic conditions. From battery systems to inverters, CHP empowers manufacturers to optimize performance, enhance reliability, and accelerate time-to-market for your products. The modular design ensures flexibility to adapt to evolving testing needs, while its intuitive Simulink interface streamlines the testing. Some of Impedyme CHP’s features include:

Off-shore WECS, on the other hand, are in bodies of water, such as seas or oceans, where wind speeds tend to be stronger and more consistent. This can lead to higher power yield compared to on-shore systems; but the construction and maintenance of off-shore wind farms can be more challenging and expensive due to the harsh environment and the need for specialized equipment. Despite the higher upfront costs, off-shore WECS offer many advantages, including the potential for larger turbine sizes and the ability to harness stronger and steady winds. Off-shore wind farms also have less visual and noise impact on nearby communities, making them an good option for renewable energy generation in densely populated areas. Both types of wind energy conversion systems offer a clean and sustainable source of power.

Additionally, these kind of WECS play a key role in microgrids by providing clean, renewable energy that enhances the sustainability of microgrids. Microgrids are localized energy systems that can operate in stand-alone or grid-connected mode. WECS in microgrids offer a range of benefits, including diversification of energy sources, improved grid stability, and support for remote or off-grid communities.

Likewise, in microgrids, during peak demand periods, wind turbines can provide additional power to balance the load, reducing load on other energy sources. In addition, during times when wind energy production exceeds local demand, surplus energy is stored for later use or given back to the main grid if the microgrid is operating in grid-connected mode.

As discussed, Power electronics play a crucial role in WECS by enabling efficient conversion and control of electrical energy. These components are essential for managing the interaction between the wind turbine generator and the power grid, ensuring that the generated power is compatible with the grid's standards, such as voltage and frequency codes.

When wind turbines generate power, the output might vary in terms of voltage and frequency depending on the wind speed. Power electronics are used to condition this electrical output, converting it into a form that matches with the power grid's requirements. This conversion is typically achieved through grid-connected inverters, which transform the variable output from the wind turbine's generator into stable AC power suitable for grid integration.

Power electronics also provide advanced control capabilities in WECS. For example, they can regulate the generator's speed and torque to optimize the energy harness from the wind. Also, power electronics enable smooth grid synchronization. Moreover, power electronics can enhance the overall stability of WECS; by controlling the reactive power, they can maintain grid voltage levels and improve power quality. Such control schemes aid in mitigating fluctuations in wind energy generation, contributing to the reliable operation of the power system.

WECS offer a clean source of power, making them an important part of the transition to a sustainable future. As this technology advances, we can see more efficient and cost-effective wind energy solutions in the coming years.

All models have now been built, and before proceeding to the tests, let us get introduced to Impedyme’s CHP technology.

Fig 8. WECS Emulation: Impedyme’s CHP Connection Diagram

We allocate the first drawer, that is the top-most drawer, for the wind turbine model and the second drawer for the AC/DC rectifier, and the third for the grid-side inverter model. Likewise, finally, the fourth drawer is dedicated for the grid. The last two, that is the two bottom-most drawers are dedicated for the Active Front end Converters that provide the DC coupling for the emulation. 

Now, let’s see how the connections are made to allocate these drawers. the power connections are given on the backside of the cabinets. The DC supply from the active front end drawer is given to the wind turbine model drawer and the 3-phase AC voltages is provided to the AC/DC rectifiers drawer. The second drawer emulates the action of a rectifier and converts the power to DC, which is subsequently provided to the inverter drawer below. The inverter now converts the DC power to 3-phase AC and is given to the grid model. Finally, the DC coupling is given back to the active front end drawer from the grid model to have a circulating power flow. Since the connections are complete, we are now ready to test.

Fig 9. Transient Response of the Emulation

Fig 10. Emulation Response for Step Wind-Speed Change

The system parameters for the experiment are as follows.

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