Short Term Voltage Stability Improvement In Power System

What is uninterruptible power supply (UPS)?

Uninterruptible Power Supplies (UPS) have reached a mature level by providing clean and uninterruptible power to the sensitive loads in all grid conditions. Generally UPS system provides regulated sinusoidal output voltage, with low total harmonics distortion (THD), and high input power factor irrespective of the changes in the grid voltage.

Why do we need uninterruptible power supplies?

However, during transmission and distribution, it is subject to voltage sags, spikes and outages that can disrupt computer operations, cause data loss and damage equipment. The uninterruptible power supplies protect the connected equipment from power problems and provide battery backup during power outages.

What is a voltage independent ups?

• VI (Voltage Independent): this is the UPS in which the variations in the power supply voltage are stabilised by electronic/passive regulation devices within the limits of routine operation .

What is a dynamic uninterruptible power supply?

For large power supplies, a dynamic uninterruptible power supply (DUPS) can be used. The synchronous motor/alternator is connected to the mains power supply through a choke. Flywheel stored the energy. In the event of a line failure, the stored current control keeps the load driven until the power of the flywheel is exhausted.

What is the minimum power factor for UPS?

According to the IEEE standard ANSI/IEEE 446–1987, minimum power factor is 0.8 at the rated load and harmonics content less than 5% is preferred for the input rectifier of the UPS system. Table 8. Typical 3-Ø UPS System Specification by ANSI/IEEE 446–1987 . Fig. 27. Input Voltage and Current waveform.

How many output voltages can an UPS system provide?

This UPS system can be operated at two different voltage levels and can also provide two output of 110 V.The proposed UPS topology consist of a battery charger, three level boost rectifier, and a double half bridge inverter. The double half bridge inverter generates two independent 110 V AC output voltages.