Power System Stability and Transient Analysis

NPPT performs detailed analyses of the stability, dynamic behavior, and transient response of power systems, in particular low-inertia systems with inverter-based and rotating sources. Protection aspects (system relaying, UFLS, inverter and generator protection and so forth) are included as appropriate for the particular study. NPPT offers an array of specialized technical and engineering services from project initiation all the way to operation and customer satisfaction assurance, including:

  • Electromagnetic transient(EMTP-type), phasor-domain(PSS/E-type), and HIL-based simulation studies in support of planning, design, and operations, to facilitate
    • Full understanding of system stability and dynamic response under various use-case scenarios
    • Selection and sizing of inverters, generators/controllers/AVRs, and energy storage
    • Design of controls to meet stability, dynamic and transient performance objectives, for use cases that may include faults, load switching, or on-to-off-grid transitions
    • Protection system design and specification
  • Design, implementation, testing and monitoring of BESS systems and controls for various forms of low-inertia system support (see NPPT’s BESS capabilities document for more on this)
  • Design, execution and interpretation of tests and commissioning, in the laboratory or in the field
  • Measurement and simulation-based analysis and diagnosis of performance issues in fielded systems
  • Event, failure, and root-cause analysis

NPPT provides these services with an exceptional level of skill, professionalism, responsiveness, and creative but practical thinking. If you have a need that does not appear on this list, please contact us to discuss it.

Example projects

A brief listing of a few relevant recent projects includes the following.

Power system engineering for a whole-feeder microgrid in the north western US. This was a 5 MW microgrid comprised of a distribution circuit hosting both diesel generation and PV, and seamless transitions between on-and off-grid modes were desired. Specific duties:
  • Construction of a detailed transient model of the entire system
  • Design of all controls for the battery energy storage system
  • System stability, fault response, loss of generator, and load switching/loss of load dynamics studies
  • Recommendations for adjustments to generator controls for microgrid compatibility
  • Design of a load-shedding scheme
  • Design, execution and interpretation of system laboratory and field tests
Power system engineering for a battery-inverter system for frequency support on a small island grid. This was a roughly 5 MW diesel-based island grid in which PV penetration levels are becoming high (on an instantaneous power basis, sometimes as high as 90%).Specific duties:
  • Construction of a detailed transient model of the entire island grid
  • Battery system sizing
  • Design of all controls for the battery-inverter system
  • System stability, fault response, loss of generator, load switching/loss of load, and varying-irradiance dynamics studies
  • Complete system protection and underfrequency load shedding reviews
  • Design and interpretation of system tests