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Grid-Forming Control Based On Emulated Synchronous Condenser Strategy Compliant With Challenging Grid Code Requirements

Julian Freytes, Antoine Rossé, Valentin Costan, Grégoire Prime

TL;DR

The paper tackles the challenge of maintaining stable grid-forming operation for inverter-based resources under severe grid events, where current limiting can destabilize conventional VSM-based controllers. It proposes a Grid-Forming strategy that combines an Emulated Synchronous Condenser (ESC) in parallel with a current source; ESC dynamics follow a swing-equation-like model with $P_{ESC}^*=0$ and $P_{ESC}=\bm{v_{sdqpn}} \cdot \bm{i_v}$, while the current source enforces fast active-power tracking. This yields a single, logic-light control structure capable of handling balanced and unbalanced Fault Ride-Through, main-grid disconnection, black start, and extreme phase jumps, as validated by time-domain simulations on a 2-MW BESS. The approach promises robust inertial and primary-frequency characteristics for high shares of inverter-based generation, reducing the need for ad hoc fault-detection or switching logic. Overall, the ESC–current-source GFM framework offers practical resilience for future grids with stringent grid-code requirements and limited current headroom.

Abstract

Future power systems will include high shares of inverter-based generation. There is a general consensus that for allowing this transition, the Grid-Forming (GFM) control approach would be of great value. This article presents a GFM control strategy which is based on the concept of an Emulated Synchronous Condenser in parallel with a controlled current source with an explicit representation of the swing equation. The advantage of this control is that it can cope with challenging grid code requirements such as severe phase jumps, balanced and unbalanced Fault Ride-Through (FRT), main grid disconnection and black start. All these scenarios can be surpassed with a single control structure with no further logic involved (e.g. fault detection to turn on or off different control parts, freezes, etc.). The proposed strategy is evaluated via time-domain simulations of a 2-MW Battery Energy Storage System (BESS).

Grid-Forming Control Based On Emulated Synchronous Condenser Strategy Compliant With Challenging Grid Code Requirements

TL;DR

The paper tackles the challenge of maintaining stable grid-forming operation for inverter-based resources under severe grid events, where current limiting can destabilize conventional VSM-based controllers. It proposes a Grid-Forming strategy that combines an Emulated Synchronous Condenser (ESC) in parallel with a current source; ESC dynamics follow a swing-equation-like model with and , while the current source enforces fast active-power tracking. This yields a single, logic-light control structure capable of handling balanced and unbalanced Fault Ride-Through, main-grid disconnection, black start, and extreme phase jumps, as validated by time-domain simulations on a 2-MW BESS. The approach promises robust inertial and primary-frequency characteristics for high shares of inverter-based generation, reducing the need for ad hoc fault-detection or switching logic. Overall, the ESC–current-source GFM framework offers practical resilience for future grids with stringent grid-code requirements and limited current headroom.

Abstract

Future power systems will include high shares of inverter-based generation. There is a general consensus that for allowing this transition, the Grid-Forming (GFM) control approach would be of great value. This article presents a GFM control strategy which is based on the concept of an Emulated Synchronous Condenser in parallel with a controlled current source with an explicit representation of the swing equation. The advantage of this control is that it can cope with challenging grid code requirements such as severe phase jumps, balanced and unbalanced Fault Ride-Through (FRT), main grid disconnection and black start. All these scenarios can be surpassed with a single control structure with no further logic involved (e.g. fault detection to turn on or off different control parts, freezes, etc.). The proposed strategy is evaluated via time-domain simulations of a 2-MW Battery Energy Storage System (BESS).
Paper Structure (16 sections, 6 equations, 12 figures, 1 table)

This paper contains 16 sections, 6 equations, 12 figures, 1 table.

Table of Contents

  1. Introduction
  2. Grid-Forming with Classical Virtual Synchronous Machine
  3. Virtual Synchronous Machine (VSM)
  4. Voltage Control and Virtual Impedance
  5. Reference Current Limitation and Current Control
  6. Instability of VSM during current limiting
  7. Grid-Forming Control with Emulated Synchronous Condenser
  8. Emulated Synchronous Condenser (ESC)
  9. Current Source: Active Power Control
  10. Evaluation of GFM control for challenging requirements via time-domain simulations
  11. Power step and power reversal
  12. Black start
  13. Main grid disconnection
  14. Fault Ride-Through Scenario
  15. Extreme Phase-Jump Followed by RoCoF
  16. ...and 1 more sections

Figures (12)

  • Figure 1: Emulated Synchronous Condenser (ESC) ABB_GFVC.
  • Figure 2: BESS Grid-forming system.
  • Figure 3: Grid-Forming Control with Classical Virtual Synchronous Machine.
  • Figure 4: Voltage Controller with reactive power droop "AVR" in Fig. \ref{['fig:GF_Ctrl']}.
  • Figure 5: VSM Instability during current limitation --- Top: ac currents in [p.u.] with $I_{base}^s$; Bottom: ac frequency in [Hz].
  • ...and 7 more figures