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Load Flow Analysis



Load flow studies determine the voltage, current, active, and reactive power and power factor in a power system. Load flow studies are an excellent tool for system planning. A number of operating procedures can be analyzed, including contingency conditions, such as the loss of a generator, a transmission line, a transformer, or a load. These studies will alert the user to conditions that may cause equipment overloads or poor voltage levels.
Load flow studies can be used to determine the optimum size and location of capacitors for power factor improvement. Also, they are very useful in determining system voltages under conditions of suddenly applied or disconnected loads. The results of a load flow study are also starting points for stability studies.

Load-flow studies determine if system voltages remain within specified limits under various contingency conditions, and whether equipment such as transformers and conductors are overloaded. Load-flow studies are often used to identify the need for additional generation, capacitive, or inductive VAR support, or the placement of capacitors and/or reactors to maintain system voltages within specified limits.

Compliance: The load-flow study will be performed in accordance with the recommended practices and procedures set forth in ANSI/IEEE 399, following the NETA recommendations.

Study Report: Following the NETA recommendations, the results of the load-flow study are summarized in a final report containing the following items:

* Basis, description, purpose, and scope of the study.

* Tabulations of the data used to model the system components and a corresponding one line diagram.

* Descriptions of the scenarios evaluated and the basis for each.

* Tabulations of power and current flow versus equipment ratings. The tabulation shall identify percentage of rated load and the scenario for which the percentage is based. Overloaded equipment shall be clearly noted.

* Tabulations of system voltages versus equipment ratings. The tabulation shall identify percentage of rated voltage and the scenario for which the percentage is based. Voltage levels outside the ranges recommended by equipment manufacturers, ANSI/IEEE C84.1, or other appropriate standards shall be clearly noted.

* Tabulations of system real and reactive power losses with areas of concern clearly noted.

* Conclusions and recommendations.