Formulating a simplified equivalent representation of distribution circuits for PV impact studies.

Abstract

With an increasing number of Distributed Generation (DG) being connected on the distribution system, a method for simplifying the complexity of the distribution system to an equivalent representation of the feeder is advantageous for streamlining the interconnection study process. The general characteristics of the system can be retained while reducing the modeling effort required. This report presents a method of simplifying feeders to only specified buses-ofinterest. These buses-of-interest can be potential PV interconnection locations or buses where engineers want to verify a certain power quality. The equations and methodology are presented with mathematical proofs of the equivalence of the circuit reduction method. An example 15-bus feeder is shown with the parameters and intermediate example reduction steps to simplify the circuit to 4 buses. The reduced feeder is simulated using PowerWorld Simulator to validate that those buses operate with the same characteristics as the original circuit. Validation of the method is also performed for snapshot and time-series simulations with variable load and solar energy output data to validate the equivalent performance of the reduced circuit with the interconnection of PV. 4 5

Multiphase Distribution Feeder Reduction

“…In spite of the error, methods using this assumption have shown to provide higher accuracy than other leading methods [24][25][26]. Further, the results provided in [27] demonstrate that the load type selected has minor effects on the simulation results.…”

An Alternative Proposal for Quantification of Technical Losses Using a Reduced Equivalent Circuit

“…It also allows the user to select which buses should remain in the final circuit. Technical losses are not preserved though [7]. The same disadvantages pointed out in [4] applies here as well.…”

“…Additionally, it is shown that the TL are preserved after the reduction technique for the two selected feeders. Nevertheless, this conclusion cannot be generalized since it is mathematically shown in [7] that the method philosophy does not assure TL equivalence. Unfortunately, neither [6]- [8] evaluated the TL errors in their investigations.…”

Methods for Analyzing the Benefits and Costs of Distributed Photovoltaic Generation to the U.S. Electric Utility System

“…This clustering validation could also be used to estimate the level of error introduced by clustering rather than modeling all feeders. In many cases, computational demands can be reduced further by using simplified equivalent distribution networks with aggregated loads (Reno et al 2013;Baggu et al 2014).…”