Power Flow Calculation in Distribution Networks Using Forward/Backward Sweep Method

Power flow calculation in distribution networks is a critical component of power system analysis, primarily used to determine voltage, current, and power distribution at each node within the network. Due to the radial structure, high impedance ratio, and three-phase imbalance characteristics typical of distribution networks, high-precision algorithms like the Newton-Raphson method may exhibit low efficiency or even fail to converge in such systems. Consequently, the Forward/Backward Sweep Method emerged as a specialized power flow calculation technique tailored for distribution networks.

The core concept of the Forward/Backward Sweep Method divides the power flow calculation into two main phases: the forward sweep (propagating power or current from terminal nodes toward the root) and the backward sweep (updating voltages from the root toward terminal nodes). This algorithm leverages the tree-like topology of distribution networks through iterative computations to gradually approach the accurate solution, offering advantages such as fast computation speed, robust convergence, and low memory requirements.

Specifically, during the forward sweep phase, the algorithm starts from load nodes and propagates power or current upstream along feeders, aggregating flow information from all branches. The backward sweep phase initiates from the source node, progressively correcting voltage values at downstream nodes based on known voltage and impedance parameters. These two phases alternate iteratively until the voltage difference between consecutive iterations meets predefined accuracy thresholds.

This method is particularly suitable for modern distribution networks incorporating distributed generation. With appropriate modifications, it can handle complex scenarios like network reconfiguration and fault analysis. Compared to traditional methods, the Forward/Backward Sweap Method demonstrates low sensitivity to initial values and naturally accommodates weakly meshed networks, making it a practical tool for engineers analyzing distribution network operational states.

Key implementation aspects include: - Node numbering optimization for efficient tree traversal - Building network admittance matrices considering phase imbalances - Implementing convergence checks using voltage magnitude tolerances - Handling distributed generators through negative load modeling - Supporting sectionalizing switches for network reconfiguration scenarios