Erlangen, Germany, March 31, 2010 — Siemens Energy has received an order worth about $88 million million from Saudi Arabia to supply three turnkey static reactive-power compensation systems.
The parallel compensation systems will be deployed at three sites in the Hiteen, Qassim and Afif substations and are scheduled to be ready for operation between mid-2011 and early 2012.
The three systems ordered are intended for the 380-kV, 132-kV and 33-kV voltage levels and will have a dynamic compensation capacity of as much as 800 MVAr.
Reactive-power compensation systems compensate voltage and load fluctuations in high-voltage transmission networks and thus ensure stable operation. As a result of the increasing power demand in Saudi Arabia the local grid will be exposed to higher loadings and this will make it necessary to implement additional measures for grid stabilization.
The thyristor valves of Siemens SVC systems are equipped with direct light-triggered thyristors, which ensure enhanced reliability. The control system for the SVC systems is based on Simatic TDC, the field-proven multiprocessor automation system, which is deployed in particular in large systems for process, energy and drive technology.
Static reactive-power compensators with dynamic control are part of FACTS (Flexible Alternating Current Transmission Systems) technology. Siemens’ FACTS systems control the parameters, which dictate the operation of a power supply network and thus the quality of power transmission. These parameters include transmission impedances, currents, voltages and phase angles between the different system nodes.
With reactive-power compensation a distinction is made between parallel and serial compensation: serial compensation systems are capacitor banks inserted in the high-voltage cable run — possibly in combination with thyristor-controlled reactors.
This fixed or variable serial impedance reduces the transmission angle so that higher active power can be transmitted without endangering grid stability. With parallel compensation a variable reactive power source feeds into a selected grid point via a transformer. This is where the required reactive power is generated to keep the voltage constant. Grid voltage may be subject to undesirable fluctuations as a result of load rejection or grid faults such as short circuits, which have to be quickly compensated.
This is the task fulfilled by static Var compensators within a power range previously matched to the grid in question. These systems are therefore always specially customized solutions.