Mott MacDonald has extensive expertise in the modeling of power system transients using electromagnetic transient programs. Our experience covers the entire range of transient events from low frequency subsynchronous turbine generator torsional vibrations (<50hz), midfrequency="" switching="" transients="" (50hz="" to="" 20khz),="" and="" high-frequency,="" fast="" front="" studies="" (up="" to=""></50hz),>
For studies, we often use the most advanced electromagnetic transients program, PSCAD/EMTDC. Our applied transient modeling techniques enable us to understand and determine appropriate mitigation for nonstandard power system problems.
Mott MacDonald has used transient studies to identify potential issues on new build systems and has successfully explained and devised appropriate mitigation for transient problems experienced on operational systems.
We focus on issues of concern immediately and model the system in appropriate detail, avoiding the common mistake of including too much elemental information when not required. We achieve the required detail in results without affecting accuracy. These factors enable work to be carried out quickly and cost-effectively: important benefits in a technological area where analysis can be expensive and time-consuming.
Cooperation with the developers of the PSCAD/EMTDC program has led to the development of new models and features in the program based on requirements identified during our system studies.
Our extensive expertise includes:
- Assessment of electrical and mechanical system interactions in variable speed drives and turbine generators
- Assessment of fault current limiter operation
- Circuit breaker transient recovery voltage calculations
- Development of turbine generator controllers
- Insulation coordination and assessment of rating
- Overhead transmission line and cable transients
- Placement of surge arresters
- Transformer inrush and capacitor and filter bank switching transients
- Unique pulse power applications
While systems modeling relies on quality software, it is even more reliant on quality analysts who understand the phenomena being modeled.
Our experts have experience in most system types and in interpreting model results. This means we can provide solutions to problems during the design stage, the most cost-effective time to implement changes, or on existing systems where operational difficulties are traced to issues that need to be modeled to understand and alleviate them.
Mott MacDonald has used PSCAD/EMTDC to model system harmonics and interharmonics in the time domain – where standard frequency domain techniques may not be suitable – by modeling converters at switching device level. We can import data from standard load flow programs directly into time domain models using the ETRAN translation program. This allows detailed and harmonic impedance calculations to be performed using frequency dependent overhead line and cable models.
Mott MacDonald's electromagnetic transient analysis is a valuable specialized service provided by only a few consultants.
Our applied transient modeling techniques enable us to understand and determine appropriate mitigation for nonstandard power system problems.
Selected project examples
In each case we utilized analysis and modeling tools to advise on appropriate mitigation that was successfully applied in practice.
- Solution to a long-standing protection problem on a 275kV transmission system
- Identification of system over-voltages caused by transformer inrush exciting a low-frequency power system resonance
- Explanation for incorrect operation of fault current limiters in an industrial distribution system