Thyristor controlled series compensation
Hitachi Energy's Thyristor Controlled Series Compensation (TCSC) provides an advanced solution to future grid challenges. TCSC technology enhances active power transfer while mitigating the risk of sub-synchronous resonance (SSR). It enables dynamic power flow control (PFC) and facilitates active power oscillation damping (POD). The system also supports renewable integration without introducing sub-synchronous control interaction (SSCI) risks, offering effective congestion management and serving as a flexible alternative to traditional infrastructure expansion. By implementing TCSC, utilities can optimize grid performance amid evolving conditions, ensuring both resilience and operational efficiency in response to the changing demands of the energy sector.
Hitachi Energy commissioned its first TCSC installation in 1999. With more than 25 years of experience, largest installed base worldwide, we have an unmatched operational knowledge in applying TCSC for complex and high-impact transmission projects.
Applications
- Sub-synchronous resonance (SSR) mitigation
- Sub-synchronous control interaction (SSCI)
- Dynamic power flow control (PFC)
- Power oscillation damping (POD)
Design overview
Like traditional Fixed series capacitors, all the main equipment of the TCSC is installed on an insulated steel platform. The system comprises a thyristor-controlled inductor connected in parallel with the capacitor bank. Over-voltage protection is through metal oxide varistor (MOV). Control and protection systems are located at ground level and interfaced through fiber optic links to ensure high-speed, reliable operation.
How it works
Hitachi Energy's patented firing control algorithm dynamically adjusts the impedance of transmission lines using advanced power electronic devices. Notably, this algorithm provides inherent immunity to the entire sub synchronous resonance (SSR) frequencies, distinguishing it from other mitigation methods such as SSR filter solutions.
Key Benefits of TCSC
Affordability
TCSC unlocks higher usable transmission capacity. This reduces the need for new transmission corridors and lowers investment costs and losses — directly improving the cost of delivering electricity.
Timeliness
Through SSR mitigation, power oscillation damping and dynamic power flow control, TCSC strengthens system stability and protects critical generation assets.
Sustainability
TCSC supports large-scale integration of wind and other renewable sources — accelerating the transition to a low-carbon grid.
Advantages of TCSC compared to SSR filter solution
- In TCSC the advanced power electronics devices are controlled in a way that the power system perceives TCSC as an inductor at the subharmonic frequency. On the other hand, with SSR filter solution, the power system remains susceptible to SSR risk, but it is reduced by implementing a filter.
- Normally SSR filters are tuned for a particular frequency range, so any change in the network may requires filter retuning. TCSC is a robust solution for the entire SSR frequency band, so changes in the network condition has no impact.
- For TCSC compensation degree can be adjusted within the design limit whereas compensation degree is fixed in SSR filter.
- TCSC has a smaller footprint compared to the filter solution due to advanced power electronics.
- TCSC has lower losses as compared to SSR filter solution
- Power flow control is an additional feature of a TCSC that is not possible in SSR filter.
- Power oscillation damping is possible with TCSC, though not with SSR filter.
As we look toward the future grid, Thyristor Controlled Series Compensation (TCSC) stands out as a versatile solution addressing multiple challenges. This cutting-edge technology not only streamlines renewable integration by eliminating the risk of Sub-Synchronous Control Interaction (SSCI), but also alleviates grid congestion and actively dampens power oscillations. TCSC empowers utilities to build a more resilient, efficient, and sustainable transmission network.
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Frequently Asked Questions
Yes, TCSC offers inherent immunity to sub-synchronous resonance (SSR) and sub-synchronous control interaction (SSCI). At sub-harmonic frequencies, the power system perceives the TCSC as an inductor, hence any variations in the grid condition do not affect the performance of TCSC.
TCSC (Thyristor Controlled Series Capacitor) prevents control interactions between wind turbine converters and series-compensated transmission lines, thereby reducing the risk of Sub-Synchronous Control Interaction (SSCI), a critical issue in large-scale wind farm integration.
As renewable integration can lead to grid congestion, TCSC's dynamic impedance controllability provides an effective solution for alleviating such congestion.
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