OPENloop与simulink

[liuzigang0607]

I am a beginner in Openfast and I want to use Openloop's Simulink file to control Openfast. I want to use Openloop to build the controller I designed to control Openfast, but I saw that Open requires various signals to be input, including electromagnetic torque, pitch angle, and power interface. When I started building, I first used Open Loop to test whether Simulink had been jointly simulated with Openfast. Currently, I can perform joint simulation, but when I input all signals in Openloop as constant values, the output variables such as electromagnetic torque and speed fluctuate, but the power output is always a value without any fluctuations, which is the input value. May I ask? What is the reason for this

[jjonkman]

Dear @liuzigang0607,

If you input constant torque and power to the OpenFAST S-Function in Simulink, I would expect you'd receive the same values as output, assuming you've selected to use these inputs through VSContrl = 4 in ServoDyn. The generator speed would fluctuate of the generator torque does not match the aerodynamic torque.

Best regards,

[liuzigang0607]

The generator speed fluctuates due to the mismatch between the generator torque and the aerodynamic torque, while the electromagnetic torque is constant. So why is there no fluctuation in power? Is it because the power I input is constant

[jjonkman]

Dear @liuzigang0607,

Yes, that is correct. The electrical output power is simply passed through from the input and not modified by the OpenFAST S-Function.

Best regards,

[liuzigang0607]

Hello, from the pictures I uploaded, it can be seen that my input terminals are all constants. Generally, wind turbine control signals are electromagnetic torque and pitch angle. I want to see the response of each signal, including output power, under a certain input signal. However, the output power on the output data side is consistent with the constant input on the input side. As you said, the power output is directly transmitted from the input terminal without being modified by the OpenFAST S function. So, how should I view the actual power output under the current control input, which is electromagnetic torque and pitch angle signals, or should I modify the value of the input power signal

[jjonkman]

Dear @liuzigang0607,

Given that the electrical power depends on the details of the electrical drive that are assumed to be implemented in Simulink when VSContrl = 4 in ServoDyn, we've set-up the OpenFAST S-Function so that if the user wants electrical power, they have to implement that themselves, along with the generator torque. If you don't have a more sophisticated model, this could be implemented simply as the generator torque times the generator speed times some efficiency loss.

Alternative, OpenFAST has other power outputs, such as the aerodynamic-only power (from AeroDyn) and the mechanical power (from ElastoDyn), but these do not account for mechanical-to-electrical efficiency losses.

Best regards,