Quick and variable reactive power compensation
Siemens Static Var Compensators SVC Classic
Siemens' SVC Classic improves power quality by dynamically injecting the required amount of reactive power into the net. The SVC Classic achieves this fast and reliable functionality by use of state-of-the-art light-triggered thyristors (LTT). By deploying these LTTs there is no need for a delicate thyristor control on medium voltage level – a significant plus in reliability and operational safety. Depending on the application SVC Classic consists of a thyristor controlled reactor (TCR), a thyristor switched capacitor (TSC), or MSCs/MSCDNs. Its modular design provides customized solutions for different requirements.
Whenever fast voltage regulation is required to reliably fulfill voltage stabilization tasks, either in the grid or for large industrial loads, SVC Classic is a proven solution.
Various control concepts can be combined with a wide range of configurations to match individual applications.
In that way the SVC Classic solutions can be optimally tailored to suit a wide range of requirements:
- They increase grid reliability by assisting fault recovery and thus reduce the risk of blackouts. They improve the power factor by dynamically providing reactive power
- They symmetrize unbalance between phases
- They reduce flicker of large industrial consumers like electric arc furnaces
- They help industrial customers to achieve more efficient operation by stabilizing the voltage that supplies the plant
A large variety of SVC Classic concepts covers the wide spectrum of applications. Typical voltage levels range from lower medium voltage up to 800 kV, with typical overall power ratings of up to 1,000 Mvar.
Concepts tailored to your application and grid’s requirements
The simplest configuration combining a TCR with filter circuits is typical in industrial applications. But – owing to modular design and individual adaptability – the SVC Classic also offers suitable concepts for more complex requirements in grid and industry applications: a tailor-made control concept is combined with the appropriate selection of type and number of parallel branches of different characteristics.
Continuous adjustment of inductive reactive power
The core functionality of an SVC Classic is the ability to dynamically adjust inductive reactive power with a thyristor controlled reactor (TCR). This adjustment, performed automatically by the control system based on the dynamic grid requirements respectively the load characteristics, results in the stabilizing effect of the SVC Classic. TCRs do not generate transients, but they generate harmonic currents at firing angles above 90°. These harmonics need to be dampened by individually tuned filter circuits.
Damping harmonics while providing capacitive reactive power
Filters circuits enhance the capabilities of the SVC Classic. To absorb harmonics prevalent in the system or generated by the TCR, they are tuned to specific frequencies. Number and frequency characteristics are individually selected. Where necessary, high- and low-pass filters further improve effectiveness.
In industrial applications usually the principle of “indirect compensation” is usually applied: filters of the SVC Classic are designed to provide a defined capacitive reactive power at base frequency – the inductance of the reactor, dynamically controlled to complement the varying reactive load, that the reactive power of all three components adds up to approximately zero.
Stepwise injection of capacitive reactive power
A thyristor switched capacitor (TSC) is used to inject capacitive reactive power step by step, if called for by transient phenomena during switch-on. Instead of being controlled continuously, they are switched on and off when needed.
TSCs do not generate harmonic distortion in the transmission line.
In industrial plants this is not a common solution.
Be in control
Effective control method
The SVC Classic is a highly dynamic, fast, and reliable alternative to conventional mechanically switched reactors and capacitors. A sophisticated control with algorithms tailored to the respective application allow its use to either dampen power oscillations in the grid or for fast load compensation. Voltage control to stabilize a power grid or voltage stabilization to improve the efficiency of an industrial power distribution and the loads connected are tasks for which the SVC Classic is an attractive answer.