Real Time Digital Simulator
Naveen Sabbavarapu, B.Tech (4/4)
Simulation: Simulation is the study of behaviour of a physical system based on models of same
key characteristics. The model represents the system and Simulation represents the operation of
the system.
Simulation is an important and necessary tool in the development, design and testing of
Power generation and Transmission systems.
Under disturbed conditions in the power system such as Transients, Faults etc., the
components in the system are subjected to stresses which far exceed those experienced
during normal operation. Simulations are performed to examine the stresses and their
effects on the system.
The algorithms necessary for software based electromagnetic transients simulations were
first described by H.Dommel.
Real time simulation implies that an event in the power system which lasted for only one second
can be implemented on the simulator exactly in one second. The advances in Digital Signal
Processing together with the improvement in accuracy and efficiency of power system models
lead to Real Time Digital Simulator (RTDS).
RTDS: : Real time digital simulator is a combination of specialized hardware and software
specifically designed for solution of power system electromagnetic transients in real time. The
actual hardware controllers / protective relays can be tested in closed loop with RTDS.The RTDS
components can be explained as below:
HARDWARE:
It comprises of Digital Signal Processors (DSP) and Reduced Instruction set
Computer(RISC).
Uses parallel processing techniques to achieve computation speeds to maintain
continuous real-time operation.
Simulator computes the state of power system at distinct time intervals, named as
“SIMULATION TIME STEP (∆t)”, usually 50µs.
RACK: 19 inch housing consisting of upto 20 printed circuit boards. RTDS makes use of 2
types of processor cards in each rack
1)Triple Processor Card(3PC) –3 analogue devices, ADSP21062(digital signal processors) of clock
speed 40 MHz.
2) Giga Processor Card(GPC)—2 IBM 750 GX Prcessors, clock speed:1 GHz.
In addition to these cards, an RTDS rack always contains a Work-Station Interface
Card(WIF) and in case of multi rack systems, an Inter-rack Communication card(IRC).
SOFTWARE:
It comprises of accurate Power system component models to represent the elements of
power system.
Network solution is obtained based on “NODAL ANALYSIS” and the algorithm used is
Dommel’s solution algorithm and Trapezoidal rule of integration.