Impact of Reactive Power Generation and Absorption on Voltage Regulator: A Case Study in an Industrial Power System

Abstract

The stability and reliability of any electrical power system, particularly in industrial settings, relies heavily on the meticulous control of reactive power (RP) flow and subsequent voltage regulation. Theoretically, the instantaneous amount of reactive power required is fundamentally dependent upon the prevailing voltage level. Maintaining voltage within acceptable limits is critical, as voltage drops can significantly impact the operational efficiency and life expectancy of connected equipment. Reactive power generation (capacitive) and absorption (inductive) characteristics dictate the voltage profile; voltage rise often requires reactive power absorption, while voltage drop necessitates generation. The Automatic Voltage Regulator (AVR) serves as the primary voltage control system for synchronous generators. The AVR operates by controlling the generator excitation system to regulate the generator’s terminal voltage. When a voltage reduction is detected (such as during heavy industrial load changes), the AVR responds by increasing the generator excitation, which consequently boosts the generator Electro-Motive Force (EMF) and increases the amount of reactive power generated, thereby raising the terminal voltage to the desired set point. This study analyzes the dynamic performance of the AVR using transfer function models for its core components: the amplifier, exciter, generator, and sensor. While the basic AVR model may exhibit instability, simulation results demonstrate that stabilization techniques improve response. Specifically, the Proportional-Integral-Derivative (PID) controller is highlighted as a highly effective industrial process control method.

Introduction

Voltage and Reactive Power Control in Industrial Power Systems:
Secure and reliable industrial power delivery relies on voltage and reactive power (RP) control, which is essential for transferring active power efficiently. Proper reactive power management ensures system stability, reliability, and protection against voltage collapse, while poor control can cause equipment damage, increased losses, and reduced lifespan. Industrial load variability and transmission line characteristics require responsive voltage regulation mechanisms.

Automatic Voltage Regulator (AVR):
The AVR maintains generator terminal voltage by controlling excitation. It operates via feedback from potential transformers, comparing sensed voltage with a reference to adjust field current. For dynamic stability, PID controllers and rate feedback stabilization improve transient response and minimize steady-state errors.

Reactive Power Compensation:
Reactive power is generated by shunt capacitors, synchronous generators, and PV systems, and absorbed by inductive loads and transmission lines. Compensation devices include:

• Shunt Capacitors: Inject reactive power near load centers for voltage support.

• FACTS Devices: Provide dynamic control, including SVCs (thyristor-based) and STATCOMs (VSC-based), with STATCOMs offering faster response, voltage support during deep sags, and low harmonic distortion.

Voltage Regulation Technologies:

• Mechanical/Static Regulators: OLTCs and capacitor banks adjust voltage slowly and in steps.

• Synchronous Condensers: Provide dynamic reactive power and inertia but are bulky.

• Thyristor-Based FACTS (SVCs): Enable fast reactive power control electronically.

• VSC-Based FACTS (STATCOMs): Offer high precision, rapid response, and efficient reactive power control for dynamic industrial loads.

Industrial Applications:

• Electric Arc Furnaces (EAFs): SVCs improve power factor, reduce flicker and harmonics, and increase furnace capacity.

• Hot Rolling Mills: Distributed STATCOMs stabilize voltages, minimize reactive power drawn from the grid, reduce harmonic distortion, and optimize operation efficiency.

Overall:
Effective voltage and reactive power management in industrial systems combines AVR control, reactive power compensation, and FACTS technologies. Modern devices like STATCOMs and distributed compensation strategies provide fast, reliable, and scalable solutions to maintain voltage stability, enhance power quality, and improve industrial process efficiency.

Conclusion

Reactive power control is mandatory to maintain rated voltages at all nodes in industrial and long-distance transmission systems and to minimize losses. The Automatic Voltage Regulator (AVR) is critical for system operation, regulating the generator\'s terminal voltage and RP output by controlling the excitation field. Simulation comparison proves that the dynamic performance of the AVR is significantly enhanced through the implementation of a PID controller, which eliminates steady-state errors and provides a faster, more stable response than the basic AVR or rate feedback stabilization. External compensation devices are crucial for handling system-wide reactive power imbalances. The selection of compensators (shunt inductors or capacitors) depends on whether the connected load is below or above the Surge Impedance Loading (SIL). Furthermore, the RPOOC method is demonstrated to be a practical tool for effective and optimum RP control, especially under heavy load. Recent developments utilize power electronics switching devices (FACTS) to solve reactive power control issues, offering high-speed dynamic regulation to maintain voltage stability and transfer power capability. Finally, in complex modern grids with DER penetration, control strategies must ensure sufficient reactive power reserves are available and manage regulator set points to prevent voltage violations and potential voltage collapse.

References

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Copyright

Copyright © 2025 Mr. Mohan B S, Pushpanjali N , Raghuram T S, Saleem Khan , Srinivasa R, Roshan Naika S. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.