KNOWLEDGE BASE

At its startup stage, Crimson Power Tech is currently dedicated to delivering breakthrough technologies for the electric power grid with series capacitor compensation. Our goal is to eliminate subsynchronous oscillation and achieve up to 100% series compensation efficiency. By doing so, we aim to dramatically improve the efficiency, safety, reliability, and overall performance of power generation, transmission, and consumption—from the supply side to end users. 

What is series capacitor compensation?

Series capacitor compensation is a method used in electric power transmission systems to improve the efficiency and stability of long transmission lines. At the core of every series compensation system lies the capacitor bank, strategically installed in series along transmission lines to counteract inductive reactance.

What are the benefits of series compensation?

Series capacitor compensation is a method used in electric power transmission systems to improve the efficiency and stability of long transmission lines. At the core of every series compensation system lies the capacitor bank, strategically installed in series along transmission lines to counteract inductive reactance.

Series compensation offers several important benefits for power transmission systems:

1. 1. Increased Transmission Capacity – By reducing the effective line reactance, series capacitors allow more current to flow through the line, effectively increasing the power transfer capability without building new lines.

   2. Improved Voltage Regulation – Series compensation helps maintain voltage levels along the transmission line, reducing voltage drops and improving power quality for end users.

   3. Enhanced System Stability – It mitigates issues like subsynchronous resonance and power oscillations, improving both transient and dynamic stability of the grid.

   4. Reduced Transmission Losses – Lower line reactance decreases overall line impedance, which reduces resistive losses and improves efficiency.

   5. Economic Advantages – By boosting capacity and stability without constructing new lines, series compensation can significantly reduce infrastructure and operational costs.

   6. Flexible Control of Power Flow – It allows operators to manage and direct power flows more effectively, supporting better grid reliability and integration of renewable energy sources.

   7. Deferred Investment in New Transmission Lines - Increases the utilization of existing transmission infrastructure. Provides a cost-effective alternative to building new lines.

In short: Series capacitor compensation strengthens transmission capability, reduces losses, improves stability, and delays costly grid expansion. However, a well-recognized challenge emerges from the interaction of these capacitors with generators, wind and solar systems, HVDC transmission, data centers, and other components, leading to subsynchronous resonance (SSR) and subsynchronous oscillation (SSO) phenomena.

What is the subsynchronous resonance and subsynchronous oscillation phenomena?

Subsynchronous resonance (SSR) and subsynchronous oscillation (SSO) are closely related phenomena that can occur in power systems, particularly when series capacitors are used in transmission lines.

1. Subsynchronous Resonance (SSR)

Definition: SSR is a condition in which the electrical network exchanges energy with a turbine-generator or other power electronic devices at a frequency below the synchronous frequency of the system (hence "subsynchronous").

• Cause:

  • Occurs mainly when series capacitors are installed in a transmission line.

  • The line’s inductance and the series capacitor form a resonant LC circuit at a frequency below the system’s normal operating frequency.

• Effect:

  • Can induce torsional vibrations in the generator shaft.

  • May stress mechanical components of turbines and generators.

  • If not controlled, can cause equipment damage or failure.

2. Subsynchronous Oscillation (SSO)

• Definition: SSO refers to the actual oscillatory motion that happens due to SSR. It is the dynamic manifestation of the resonance.

• Characteristics:

  • The generator shaft oscillates at a frequency lower than the grid’s 50/60 Hz.

  • Can be electromechanical (shaft vibrations) or electrical (voltage/current fluctuations).

• Danger:

  • Can cause fatigue, cracking, or failure in generator shafts, turbines, and other rotating machinery.

  • Can lead to system instability if sustained.