Feeder Reconfiguration for VVO

Feeder reconfiguration alters the radial structure of a distribution network by remotely changing the open/closed status of tie switches (normally open points) and sectionalizing switches. This action transfers load segments between adjacent feeders or substations. Unlike capacitor switching, which injects reactive power locally, reconfiguration physically redirects active power flow paths, fundamentally changing the impedance between the source and the load to reduce I²R losses and mitigate voltage drop.

The primary objective function is the minimization of total system active power losses. By re-routing power through less congested or shorter paths, the algorithm reduces the current magnitude flowing through high-impedance line segments. Key metrics include:

• Loss Reduction Ratio: Percentage decrease in kW losses compared to the base configuration.
• Energy Savings: Aggregated MWh savings over a specific operational period.
• Peak Loss Reduction: Minimizing losses during maximum system stress.

Reconfiguration directly addresses voltage violations by shifting load away from heavily loaded feeders to those with spare capacity. This balances the voltage profile across the network, ensuring all nodes remain within ANSI C84.1 Range A limits. The process eliminates undervoltage conditions at feeder ends without solely relying on substation Load Tap Changers (LTCs) or line regulators, which can only boost voltage uniformly along a radial path.

A critical operational constraint is the thermal capacity of lines and transformers. The reconfiguration algorithm must ensure that transferring load does not cause an overload on the receiving feeder. The load balancing index quantifies the equitable distribution of load across substation transformers and feeders. Effective reconfiguration reduces the risk of asymmetric aging of assets and prevents nuisance tripping of protection relays due to transient overloads.

Distribution networks operate in a radial topology (tree structure) to simplify protection coordination. A fundamental constraint of any reconfiguration algorithm is maintaining this radiality while energizing all loads. The algorithm must prevent the formation of mesh loops, which would cause circulating currents and confuse overcurrent protection devices. This is mathematically enforced using graph theory and spanning tree algorithms during the optimization process.

Feeder reconfiguration operates on a slower time scale (minutes to hours) compared to local Volt-VAR controls (seconds). It provides a macro-optimization of the network topology, establishing a more efficient base state upon which faster controls like capacitor bank switching and smart inverter Volt-VAR curves can operate. This hierarchical coordination prevents conflicting control actions and ensures global optimality rather than local sub-optimization.