Portfolio of studies

This section shows a selection of study cases carried out by POWERSYS.

Insulation Coordination

  • Specification of insulation levels
  • Installation of protective devices
  • Can requires statistical and parametric studies

Example of Insulation Coordination study we carried out:
An insulation coordination analysis is performed to check if surge arresters are required in 63kV/90kV substations for a TSO.
A statistical approach is used to calculate the back-flashover rate and the mean time between failures (MTBF) without surge arresters.

Transformer Switching

  • Modeling of saturation & residual flux
  • Determination of inrush current & voltage drop
  • Statistical study

Example of Transformer Switching study we carried out:
A transformer switching study has been performed for a North-American engineering company. It consists in estimating the voltage drop at the point of common coupling of a wind plant when energizing the main power transformer. The wind plant is located at the end of a long transmission line where short-circuit power is quite low. A specific attention is devoted to the modeling of the transformer saturation. The impact of the residual flux is studied in order to estimate the maximum possible voltage drop that can appear at the point of common coupling.

Transfo

Harmonic Analysis

  • Modeling of harmonic sources
  • Determination of THDs
  • Compliance with IEEE 519-1992

Example of Harmonic Analys study we carried out:
A harmonic analysis of a large photovoltaic system is performed with EMTP-RV.
The system is composed of around 40 inverters modeled individually. The inverters are connected to the medium voltage network through Delta-Wye transformers that suppress the triple harmonics. The medium voltage (MV) network is composed of short underground cables and overhead lines connecting the MV network to the grid through a main transformer. Inverters are modeled in time domain as ideal current harmonic sources.

harmonic

Ferroresonance

  • Oscillating phenomena
  • 4 necessary elements:
    – Non-linear Inductance (PT, CVT,…)
    – Capacitance (Cable, Breaker,…)
    – Voltage Source
    – Low losses

Example of Ferroresonance study we carried out:
The risk of ferroresonance of a large photovoltaic farm is investigated.
The system is composed of short and long cables connecting solar inverters to the plant substation. A possible interaction between the cable capacitance and the inverter transformer is detected. At night time, in no-load condition, the risk of ferroresonance is highest.
The system is modeled in EMTP-RV and a special care regarding the modeling of the transformer saturation and the modeling of the cable is taken. Different events leading to ferroresonance (energization, single-phase switching, double-phase switching…) are simulated and the simulation results analyzed.

ferro

Simulation of a Permanent Magnet Motor

  • Finite-Element Analysis
  • Validation of experimental measurements
  • Estimation of:
    – Cogging Torque
    – Copper Loss in the winding
    – Torque
    – Hysteresis Losses
    – Thermal Losses
    – Iron Loss
    – Eddy Current in the Magnet

Example of finite-element analysis study we carried out:
An European tires manufacturer asked Powersys to validate through simulation the experimental measurements of the electrical and mechanical performances of a permanent magnet motor (IPM).
The model is created from the CAD geometry. On-load and no-load simulation where performed to determine the characteristics of the motor.

PM1

PM2

Development of a co-simulation toolbox for EMTP-RV

  • Capability to link EMTP-RV with the FMI standard V1 & V2
  • More than 60 programs are already compatible with this standard (Matlab/Simulink, LMS, MapleSim, Jmodelica, NI LabView, SimulationX,…)
  • Interaction with the EMTP solver
  • C++ / JavaScript / HTML

Example of development we performed:
Powersys developed the “FMI Toolbox for EMTP-RV” to make EMTP-RV compliant with the standard.
Using this toolbox, EMTP-RV can generate « FMUs » and behave like a co-simulation slave. EMTP-RV can import « FMUs » and behave like a co-simulation master.

toolbig

Substation Grounding

  • Substation Grounding grid design
  • IEEE 80-2000 Standard
  • Touch and surface potentials
  • CYMGRD software

Example of Substation Grounding analysis we performed:
For a European engineering company, POWERSYS analyzed the grounding of a 63/20kV substation in order to check the conformity with the IEEE 80-2000 standard. The substation ground resistance (Rg) and the Ground Potential Rise (GPR) were first investigated. Touch and surface potentials were calculated inside and outside the substation in order to check they were below the limits imposed by the standard.

Safety is a major concern for substation and engineers must ensure that grounding systems are capable of dissipating maximum possible fault current in order to guarantee the safety of personnel and equipment. POWERSYS has a long experience concerning grounding grid design and validation.

cymgrd1

High-Voltage Cable Switching

  • Insulation coordination
  • Cable switching
  • EMTP-RV Simulation
  • Statistical Analysis

Example of High-Voltage Cable Switching study we performed:
A transmission line operator asked Powersys to perform a frequency domain analysis for the resonance detection considering different topologies of the grid. A transient overvoltage and inrush current calculation when energizing the long HVAC cable were also performed in order to verify the insulation specification of the cable and substations equipment.

hvcable1

Cable Ampacity Analysis

  • Heating of buried cable
  • Cable modeling
  • CYMCAP software

Example of Cable Ampacity analysis we performed:
For an international engineering company, POWERSYS analyzed the ampacity of buried cables of a railway electrical network. Cables are transmitting currents up to 1.1kA at 25kV and the cable temperature have to be analyzed in the different possible formations (trefoil or flat) in order to optimize the design. It is important to model the load varying with time during week and week-end days to obtain the best possible accuracy.

Cables (conductor, shield, insulation and overall sheath) and time-varying loads are precisely modeled in CYMCAP. Temperature and ampacity are calculated in different parts of the network. Finally, POWERSYS proposed to the client a design optimizing the geometry and minimizing the risk of failure.

cymcap

Electromagnetic Interference between underground power cables and a buried pipeline

  • Electromagnetic interference
  • Inductive and capacitive coupling
  • Gas pipeline
  • EMTP-RV and Crinoline

Example of electromagnetic interference analysis we performed:
POWERSYS performed for a North American engineering company a study consisting in evaluating the magnetic coupling between a buried pipeline and a network of 34.5kV underground cables. The aim of the study was to determine the induced voltage and current on the pipeline in steady-state and fault conditions.
POWERSYS has a long experience concerning the analysis of electromagnetic interferences resulting from the inductive, capacitive and conductive couplings on telecommunication cables, pipelines, fences and all types of longs metallic overhead or underground structures installed on the vicinity of electric power systems.

electrocable