28-03-2012, 11:34 AM
Simulators for Analysis of power system phenomena
[attachment=19082]
Simulation tools for the analysis of power systems:
ON LINE
Hybrid simulator (i.e. IREQ simulator) Hydro-Québec’s research institute, Institut de recherche d'Hydro-Québec IREQ, is one of the largest integrated electrical research and testing centres in North America.
Real-time digital simulators (RTDSTM from RTDS Technologies Inc.).)
OFF LINE
HYPERSIM from Hydro-Quebec (uses the nodal approach to model the power circuit)
EMTP & its derivatives…. (BPA)
SIMPOWER SYSTEMS (uses the state space approach for power system modelling)
Features of IREQ
Real-time simulation,
Hybrid technology that includes passive, electronic (analog and digital)
models and real-time digital models,
Large number of components for simulation of large networks,
many versions of FACTs (SVC, HVDC) controllers,
Inter-connection capability with commercial control and protection
systems,
Computerized systems for test automation, data recording, on-line analysis,
post-processing and report editing, and
An integrated database system for fast storage and recall of results and
input data.
Advantages of IREQ
Simulation of a phenomena that lasts 1 second takes 1 second unlike simulation in deferred (off-line)
Voltages are scaled down to 100 V phase to phase on the simulator.
An impedance scaling factor is selected to keep the fault current below 5 A.
The scaling factor makes it possible to study all practical phenomena within a dynamic range of 10 - 50,000 A.
The frequency bandwidth of simulator components is limited to about 2.5 kHz (B.W is also a function of the complexity of the models used).
OFF line digital simulation packages EMTP
The Electro-Magnetics Transients Program (EMTP) was developed by H.
Dommel at the Bonneville Power Administration (BPA).
Its fundamental simplicity resulted from the representation of R L C elements with initial conditions.
It used the trapezoidal integration method which was both simple and
rapid in the solution of algebraic equations which could be represented by
difference equations.
The network equations are obtained using the Nodal Analysis method.
EMTP uses sparsity in the inversion of matrices ,uses of LU factorization techniques made the solution of large systems relatively rapid.
The user-specified time-step of integration was kept constant throughout the simulation.
The availability of a sub-routine for the Transient Analysis of Control Systems (TACS) enhanced its capabilities and allowed the use of control systems to be added to the simulation.
Numerical oscillations- Remedies
Interpolation techniques - avoid numerical problems .
The extra burden imposed on computation is not too severe with modern processors
Use of powerful double precision processors is therefore recommended (i.e. DSPs and RISC processors).
Decoupling of the power system network is necessary to distribute the computational burden between parallel processors .
The power system is decoupled due to the propagation delay in transmission lines.
Since real-time calculations need to be fast, iterative computational techniques for non-linear elements which may result in convergence problems are often not used.
[attachment=19082]
Simulation tools for the analysis of power systems:
ON LINE
Hybrid simulator (i.e. IREQ simulator) Hydro-Québec’s research institute, Institut de recherche d'Hydro-Québec IREQ, is one of the largest integrated electrical research and testing centres in North America.
Real-time digital simulators (RTDSTM from RTDS Technologies Inc.).)
OFF LINE
HYPERSIM from Hydro-Quebec (uses the nodal approach to model the power circuit)
EMTP & its derivatives…. (BPA)
SIMPOWER SYSTEMS (uses the state space approach for power system modelling)
Features of IREQ
Real-time simulation,
Hybrid technology that includes passive, electronic (analog and digital)
models and real-time digital models,
Large number of components for simulation of large networks,
many versions of FACTs (SVC, HVDC) controllers,
Inter-connection capability with commercial control and protection
systems,
Computerized systems for test automation, data recording, on-line analysis,
post-processing and report editing, and
An integrated database system for fast storage and recall of results and
input data.
Advantages of IREQ
Simulation of a phenomena that lasts 1 second takes 1 second unlike simulation in deferred (off-line)
Voltages are scaled down to 100 V phase to phase on the simulator.
An impedance scaling factor is selected to keep the fault current below 5 A.
The scaling factor makes it possible to study all practical phenomena within a dynamic range of 10 - 50,000 A.
The frequency bandwidth of simulator components is limited to about 2.5 kHz (B.W is also a function of the complexity of the models used).
OFF line digital simulation packages EMTP
The Electro-Magnetics Transients Program (EMTP) was developed by H.
Dommel at the Bonneville Power Administration (BPA).
Its fundamental simplicity resulted from the representation of R L C elements with initial conditions.
It used the trapezoidal integration method which was both simple and
rapid in the solution of algebraic equations which could be represented by
difference equations.
The network equations are obtained using the Nodal Analysis method.
EMTP uses sparsity in the inversion of matrices ,uses of LU factorization techniques made the solution of large systems relatively rapid.
The user-specified time-step of integration was kept constant throughout the simulation.
The availability of a sub-routine for the Transient Analysis of Control Systems (TACS) enhanced its capabilities and allowed the use of control systems to be added to the simulation.
Numerical oscillations- Remedies
Interpolation techniques - avoid numerical problems .
The extra burden imposed on computation is not too severe with modern processors
Use of powerful double precision processors is therefore recommended (i.e. DSPs and RISC processors).
Decoupling of the power system network is necessary to distribute the computational burden between parallel processors .
The power system is decoupled due to the propagation delay in transmission lines.
Since real-time calculations need to be fast, iterative computational techniques for non-linear elements which may result in convergence problems are often not used.