SYNERGEE 4.0 FAULT ANALYSIS APPLICATION TUTORIALS AND GUIDE

SYNERGEE 4.0 FAULT ANALYSIS APPLICATION TUTORIALS AND GUIDE
What are the types of fault analysis that synergee 4.0 offers?

As an overview to synergee 4.0 fault analysis, SynerGEE supports three types of fault analysis: basic fault, fault flow and fault voltage. Fault current calculations are critical for utility and customer installations. They determine the maximum available current at a given point, or device in the system. With the calculations, over-current protective equipment, such as breakers, reclosers, and fuses with a fault current rating greater than the calculated values can be selected. If the protective equipment is not rated to handle the maximum available fault current, it will not operate effectively and will cause serious injury or property damage.

Faults that occur on the electrical system are usually referred to as “short circuits”, which occurs when there is a low impedance path to the source

• Low impedance path creates high current levels
• Most common types are line-ground and three-phase faults
• Line-ground fault is characterized by a single phase experiencing unanticipated path to ground
• Three-phase fault occurs when all three phases are tied together with low resistance.

SynerGEE’s Fault Current Analysis places a fault on each section of the model, one by one, and then computes the fault current in amps for the load end of each section. The fault values include minimum and maximum line-ground, phase-phase, and three-phase faults. The distances from the substation and the positive and zero sequence impedance are accumulated along the feeder. The analysis checks the minimum fault current from the selected protective device down-line to the next section with a protective device.

Looped Fault Analysis
SynerGEE contains a robust algorithm for modelling looped distribution systems. In a radial distribution model, loops can be created directly by allowing loop creation (in the Model tab of the Preferences editor).

Fault Flow Analysis
Fault flow analysis places a fault at one location in the distribution system model and calculates the flows throughout. By-phase models of regulators, transformers, loads, and other devices are utilized. The analysis results in a report listing the by-phase or maximum current flows on each section for the line-ground, line-line, and three-phase faults at the given fault location. A bolted maximum line-ground fault and a minimum line ground fault through a fault impedance are used. If the faulted section has a neutral, a line-line-ground fault type is used. Otherwise, a line-line type is used. Fault flow analysis requires that you first set a particular section for analysis, which becomes the fault location. Pre-fault load current can be included in the results for fault flow analysis. In this case, a load-flow is run before the fault analysis and flows are stored.

Fault Voltage Analysis
Fault voltage analysis calculates voltages throughout a system due to a fault at a single location. This application combines the SynerGEE fault current calculations, fault flow analysis, and the load-flow calculations to simulate worst-case voltage conditions near the time of the fault. The calculations are performed in the following order:

• Fault flow analysis is used to determine fault current into the fault, any generators, and through tie switches foe each type of fault.
• A load-flow analysis is used to calculate load currents and the source voltage behind the feeder or substation source impedance.
• For each fault type, the fault currents and the load currents are accumulated.
• For each fault type, voltage drops are calculated throughout the feeder.

The fault voltage analysis report lists balanced or by-phase voltages and current flows for each section and for each fault type. The report also lists the percent dip, fault impedance, and percent loading of conductors and other devices. The kVA flow is also given. Fault voltage analysis requires that you first set a particular section for analysis, which becomes the fault location.

Generators During Fault Analysis
During a fault, active synchronous and induction generators behave like a voltage source behind a subtransient reactance tied to their grounding impedance. Since they are effectively a source, generators contribute to the system of equations used to handle loops.