modelSheetI10

Information

Test Case: Islanding

1. Objective

This test evaluates the behavior of a production unit operating in islanded conditions following a sudden load variation. It verifies frequency stability, voltage stability, and protection robustness.

2. Network Configuration

The test is performed on an isolated network composed of:

• One production unit
• One synchronous compensator
• One load

3. Initial Operating Conditions

3.1 Production Unit

• Active power at PCC:
  $P=0.8\cdot P_{max}$
• Reactive power at PCC:
  $Q = 0$
• Voltage at PCC:
  $U={\mathrm{Un}}_{}$

3.2 Synchronous Compensator

• Model: classical model with internal voltage source behind reactance $X_d$
• Rated apparent power:
  $S_n = S_{n,unit}$
• Reactance:
  $X_d = X_{max} = 0.3 \, p.u.$
• Inertia constant:

$H = \frac{f_0 \cdot \Delta P}{2 \cdot ROCOF \cdot S_n}$

Where:

• $f_0 = 50 \, Hz$
• $\mathrm{\Delta }P=0.1\cdot P_{max}$
• $ROCOF = 2 \, Hz/s$

Alternative formulation:

$H = 1.25 \cdot \frac{P_{max}}{S_n}$

3.3 Load

• Active power consumption:
  $P=0.8\cdot P_{max}$
• Reactive power:
  $Q = 0$
• Model:
  • Constant power load (PQ model)
  • No dependency on voltage or frequency

4. Disturbance Description

At $t = t_0$, the following step is applied:

• Active power increase:
  $\Delta P = +0.1 \cdot P_{max}$
• Reactive power variation:
  $\Delta Q = +0.04 \cdot P_{max}$

5. Expected Behaviour / Compliance Criteria

The system is considered compliant if the following conditions are met:

5.1 Protection

• The production unit must not trip due to internal protections

5.2 Stability

• The system must reach a stable operating point
• No sustained oscillations in:
  • Frequency
  • Voltage

5.3 Frequency Limits

• Frequency must remain within:

  $$49Hz\le f\le 51Hz$$

Parameters

Components