MATLAB Code Implementation of DQ Transformation Method

Implementation approach of DQ transformation method in MATLAB In power systems, DQ transformation (also known as Park transformation) is a widely used coordinate transformation method that converts three-phase AC quantities into DC quantities in a rotating reference frame, facilitating the analysis of active and reactive current components. Below are the core logic and implementation steps for DQ transformation in MATLAB: Input Signal Processing Requires three-phase voltage or current signals as input, typically represented as time series. Signals must meet symmetry requirements and can be generated through sampling or simulation. In MATLAB implementation, signals are often stored as arrays or matrices, with each column representing a phase component. Coordinate Transformation Clarke transformation (αβ transformation): Converts three-phase stationary coordinate system (abc) to two-phase stationary coordinate system (αβ), eliminating zero-sequence components (for balanced three-phase systems). The transformation matrix can be implemented using MATLAB's matrix multiplication functions like mtimes or direct matrix operations. Park transformation (DQ transformation): Based on the rotation angle (typically the grid voltage phase angle), transforms the αβ coordinate system to the rotating dq coordinate system. Here, the d-axis component corresponds to active current/voltage, while the q-axis component corresponds to reactive current/voltage. The implementation involves trigonometric functions (cos/sin) and matrix rotations, which can be efficiently handled using MATLAB's built-in math functions. Synchronized Rotation Angle Generation Obtains real-time grid voltage phase angle through Phase-Locked Loop (PLL) to ensure the dq coordinate system rotates synchronously with the grid. This can be implemented using MATLAB's control system toolbox or custom PLL algorithms with integration functions. Application Scenario Extensions Power quality monitoring: Detects harmonics, voltage sags, and other abnormalities by analyzing dq components through signal processing toolbox functions. Power control: Achieves independent active/reactive power control by directly regulating d/q axis currents using control algorithms like PID controllers. Implementation Key Points Utilize MATLAB's matrix operation capabilities for efficient coordinate transformations through optimized vectorized code. For real-time processing, combine Simulink for model building and embed C code using MATLAB Coder for performance optimization. During verification, ensure transformed DC components match theoretical values using MATLAB's validation and debugging tools. Through these steps, the DQ transformation method can be flexibly applied in power electronics control, renewable energy grid integration, and other fields, while MATLAB's numerical computing advantages significantly simplify the development process through its comprehensive function libraries and simulation capabilities.