What is Volt-Ampere Reactive (VAR)?


A Volt-Ampere Reactive (VAR) is a metric for assessing reactive power, which arises when AC electric currents and voltage fall out of synchronization. This misalignment occurs with specific loads that necessitate reactive power or VARs. Certain generators and equipment, such as capacitor banks, static VAR compensators (SVCs), and intelligent inverters, can generate VARs within the distribution system or at customer locations.

Integrated Volt-VAR Regulation/Optimization

To prevent power factor penalties, utility companies employ VAR regulation techniques to maintain a power factor ratio close to 1, indicating predominantly real power. Inductive loads like motors can elevate reactive power in the grid, lowering the power factor from 1. Utility companies deploy capacitor banks to offset inductive loads (such as motors, pumps, air conditioners, etc.) and minimize the flow of reactive power through transmission lines.

Also See: What is Voltage Protection Rating (VPR)?

High Voltage Volt-Ampere Reactive (VAR) Cost Reallocation

The movement of reactive power through transmission lines can influence voltage amplitude positively or negatively. The effective management of overall costs and power system performance is observed when voltage control and VAR control are seamlessly integrated. The presence and use of microprocessor-based algorithms, sensors, and advanced metering infrastructure have further facilitated the integration of voltage control alongside VAR control.

Traditionally, each voltage and VAR control device installed on a feeder is independently managed, focusing solely on the local level without considering the broader impact on neighboring devices. This isolated approach can lead to suboptimal effects on a larger scale; for instance, adjusting VAR at one point might adversely affect the voltage level at another.

Integrated Volt-VAR regulation also employs a two-way communication network to synchronize voltage/VAR control actions among various devices, ensuring VAR is regulated without influencing voltage. This integrated approach provides several advantages, including enhanced visibility into system operating parameters, reduced greenhouse gas emissions, and increased transmission efficiency.

Recommended: What are Voltage Rise Calculations (VRCs)?

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