2.1 Diagram and Nomenclature of the Virtual Test Bench Components

The virtual test bench implemented in the real-time simulator is shown below:

Figure 1: Virtual test bench implemented in real-time simulator

The main elements of the virtual test bench are:

• A direct current machine (DC machine) with independent excitation and an adjustable armature SC1 power voltage source and a power supply voltage from the adjustable field SC2
• A three-phase synchronous machine with a wound rotor, with a power supply voltage from adjustable field SC3 that can be disconnected using contactor (K₅) and an asynchronous starting resistor in parallel on the field.
• A detachable mechanical coupling (K₆) on the shaft connecting both machines.
• A group of controllable contactors (K₁) (K₂) (K₃) (K₄) that allow connecting the synchronous machine’s wye-coupled armature to several devices:
  • A three-phase, wye-connected, adjustable autotransformer SA1 linked to an infinite bus with a user-defined constant frequency and voltage (the default value is f_s = 60 Hz).
  • An adjustable three-phase, wye-connected, balanced, passive load so that each branch is a serial RLC (R, X_L, X_C).
  • A short-circuit three-phase module.
  • An adjustable DC voltage source SC4 in series with two fixed limiting resistors used to measure low resistances in the synchronous machine armature.
• A protection system composed of serial fuses with windings from both machines: (F_if ) (F_ia ) (F_jf ) (F_ia ) (F_ib ) (F_ic ). Fuse rating and their I²t were adapted to specifications of both machines.

The measurement devices associated to the virtual test bench are only represented by their measured quantities: DC voltages V_a & V_f, DC current I_a & I_f, rotational speed of shaft N and torque T_u, RMS value of the voltage line-line U_s and line current I_s, total active and reactive power P & Q exchanged at the synchronous machine’s armature. Oscilloscopes not shown on Fig.1 allow users to view or capture waveforms and instantaneous values.

Detailed descriptions of the adjustable elements (power supplies and contactors) accessible to the user on the panel of the simulator are provided in section 3 of this document.

2.2 Virtual Test Bench Configuration Examples Based on Operating Modes

2.2.1 Synchronous Machine Operating in Generator Mode and Connected to a Grid

Figure 2 shows an example of how the virtual test bench can be virtually connected by the synchronous machine user in generator mode, connected to the AC grid (open contactors and de-energized circuits are not represented).
This configuration is used in exercise 3.

Figure 2: : Bench configuration to operate the synchronous machine in generator mode, connected to infinite bus

2.2.2 Synchronous Machine Operating in Generator Mode and Connected to a Passive Load

Figure 3 shows an example of how the user can virtually connect the test bench to use the synchronous machine in generator mode, feeding the passive load (open contactors and de-energized circuits are not represented).
This configuration is used in exercise 2.

Figure 3: Bench configuration to operate the synchronous machine in generator mode feeding a passive load

2.2.3 Synchronous Machine Operating in Motor Mode

Figure 4 shows an example of how the user can virtually connect the test bench to use the synchronous machine in motor mode (open contactors and de-energized circuits are not represented).
This configuration is used in laboratory exercise 4.

Note that, in this configuration, the power supplied by the DC machine operating in generator mode is automatically dissipated using a resistance R_ch on the armature terminals.

Figure 4: Bench configuration to operate the synchronous machine in motor mode

2.3 Electric Machines Nameplate Ratings

Table 1: Synchronous machine nameplate ratings

Table 2: DC machine nameplate ratings