STATCOM (Static Synchronous Compensator) and capacitor banks are both used for reactive power compensation in power transmission systems, but they have some key differences and advantages.

Advantages of STATCOM over capacitor banks:

Fast Response: STATCOM provides faster response times compared to capacitor banks. It can regulate the reactive power output almost instantly, making it suitable for compensating rapidly varying loads or dynamic system conditions. This quick response helps maintain power system stability and voltage quality.

Continuous Control: STATCOM offers continuous and dynamic control of reactive power. It can actively inject or absorb reactive power in real-time, adjusting the voltage and power factor to meet system requirements. In contrast, capacitor banks provide fixed reactive power compensation and cannot be quickly adjusted.

Voltage Support: STATCOM can regulate the voltage profile of the power system. It can inject or absorb reactive power to control voltage fluctuations, voltage dips, or voltage flicker. This capability improves the voltage stability and reliability of the system.

Reactive Power Management: STATCOM can actively manage and control the reactive power flow throughout the transmission system. It can compensate for reactive power fluctuations, voltage drops, or reactive power imbalances, ensuring efficient power transfer and reducing transmission losses.

Harmonic Compensation: STATCOM can mitigate harmonic distortions present in the power system. It can inject harmonic currents of opposite phase to cancel out the harmonic components, thereby improving power quality by reducing total harmonic distortion (THD).

Advantages of capacitor banks over STATCOM:

Cost: Capacitor banks are generally less expensive compared to STATCOM. They consist of a simple arrangement of capacitors and associated switching equipment, making them a cost-effective solution for providing reactive power compensation.

Simplicity: Capacitor banks are relatively simpler in design and operation compared to STATCOM. They have no active power electronics and can be easily installed and maintained.

Power Factor Correction: Capacitor banks are effective in improving power factor by providing reactive power compensation. They can help reduce or eliminate reactive power charges imposed by utilities, resulting in lower electricity bills for consumers.

Overvoltage Protection: Capacitor banks can help suppress voltage spikes and overvoltages in the system by absorbing reactive power during high-voltage conditions. This feature helps protect equipment from potential damage.

In summary, STATCOM and capacitor banks offer different advantages based on the specific requirements of the power transmission system. STATCOM provides faster response, continuous control, voltage support, flexible reactive power management, and harmonic compensation. On the other hand, capacitor banks are cost-effective, simple, and suitable for power factor correction and overvoltage protection.