The Application of SVG in Power Quality Management Products

1. Background and Current Situation

With the rapid development of modern power systems, particularly the large-scale integration of intermittent distributed energy sources like photovoltaic and wind power, and the widespread use of impact loads like electric arc furnaces and rolling mills, grid requirements for power quality, particularly reactive power balance and voltage stability, are becoming increasingly stringent. Traditional reactive power compensation methods primarily rely on switch-switched capacitors (MSCs) and thyristor-switched capacitors (TSCs), which provide step-like capacitive reactive power by switching capacitor banks in groups.

However, these traditional compensation devices have significant inherent drawbacks: low compensation accuracy, slow response speed (often reaching the order of seconds), prone to resonance with grid inductance during system voltage fluctuations, inability to smoothly and continuously regulate reactive power, and difficulty coping with rapidly changing load demands. These shortcomings render them inadequate for the complex modern power grid environment and may even contribute to deteriorating power quality.

2. Project Background

A mining group previously used traditional capacitor banks for reactive power compensation. However, their production equipment, such as crushers and ball mills, exhibited fluctuating loads with impacts, resulting in dynamically changing reactive power demands. Capacitor banks, however, could only be switched on and off with fixed capacities, lacking precise adaptation. This led to frequent overcompensation, resulting in abnormal increases in grid voltage and increased equipment losses. Furthermore, the inherent inductance of the capacitors and the grid easily formed an LC resonant circuit. This resonant circuit was triggered by fluctuating operating conditions, generating overcurrent and overvoltage, which damaged the capacitors.

3. Solution

(1) SVG Reactive Power Compensation Retrofit Solution for a Mining Group

Our engineering team conducted an on-site survey of the mining group's facility, thoroughly understanding the spatial layout of the reactive power compensation room, grid connections, and production load characteristics. Combined with professional power quality testing, they pinpointed the root causes of overcompensation and resonance issues in the existing capacitor bank and developed a customized SVG retrofit solution.

The existing capacitor bank was completely removed. Based on the spatial dimensions, load-bearing conditions, and ventilation layout of the existing reactive power compensation room, we optimized the SVG cabinet layout, wiring patterns, and cooling system. This ensured the SVG equipment was precisely adapted to the on-site installation environment, eliminating the need for major structural modifications to the existing plant and minimizing the complexity, time, and cost of the retrofit.

This SVG solution enables continuous and precise reactive power regulation, completely resolving overcompensation issues. It also features active harmonic suppression, ensuring safe and stable equipment operation. It also adapts to the mining industry's fluctuating loads, improving power quality and production continuity.

(2) Key Achievements of the SVG Upgrade

After its commissioning, the SVG addressed the issues of the original capacitor compensation system with precise control, achieving significant results:

Voltage Stability 

The SVG responds to changes in load reactive power in real time. By dynamically adjusting reactive power output, it quickly smooths voltage fluctuations caused by impactful loads, stabilizing bus voltage within ±2% of the rated value. This prevents sudden voltage spikes and dips that can impact equipment like crushers and ball mills, ensuring continuous and stable operation of production equipment.

Harmonic Control

The SVG monitors the grid's primary harmonics (3rd, 5th, and 7th harmonics) in real time and actively outputs reverse harmonic current to offset interference, effectively preventing harmonic damage to precision equipment on-site and reducing the risk of equipment failure.

Power Factor Optimization

With a response speed of less than 5ms, the SVG enables continuous and smooth adjustment from rated capacitive to inductive reactive power, accurately matching the dynamic reactive power requirements of the load. This completely resolves the overcompensation issue of the original capacitor bank, maintains a stable system power factor between 0.95 and 1, eliminates reactive power feedback, and reduces grid line losses and equipment losses.

For many years, we have focused on the research, development, and application of power electronics technology. We hold complete intellectual property rights for our SVG products, which are widely used in industries such as wind power, photovoltaics, metallurgy, and coal mining. Our market share has increased annually, and we have been recognized as a champion in the manufacturing industry. We strive to fulfill our corporate vision of "saving energy and serving society," contributing to the nation's goal of achieving its dual carbon emissions goals.