SVG Applications at Photovoltaic (PV) Sites

Project Background

  With the establishment of China's "dual carbon" goals, significant development opportunities and broad prospects have emerged for the photovoltaic (PV) Power Generation industry. The State Council released a notice about the 2030 Carbon Peak Action Plan. It clearly states that wind and solar power capacity should exceed 1.2 billion kilowatts by 2030.

As more people use PV power generation, many have seen Power Factor adjustment fees on their electricity bills. These fees can be high and lead to substantial financial losses for users.

 

Problem Analyzing

The "Power Factor Adjustment Fee Method" requires industrial users. They must maintain a monthly average power factor above 0.9. If they do not, they will face power penalties.

You can find the average power factor by looking at the user's monthly active and reactive power use. We use this formula:

Users usually have capacitor compensation cabinets set up on-site. These cabinets help with Reactive Power Compensation. This leads to low reactive power use and a power factor above 0.9. As a result, users can avoid power penalties.

After adding PV power generation, the utility meter shows less active power. This is because PV generation only gives active power. The reactive power stays the same.

As a result, the power factor drops. When the PV generation matches or exceeds the load, the meter shows zero active power. This leads to exceptionally low monthly active power use and a low power factor.

 

Industry Status

Most factories now use traditional capacitor switching for reactive power compensation. This method has slow response times and low accuracy. When there is no PV system, capacitor compensation has some limits.

However, the leftover reactive power is small. We compare this to the high active power use from the grid. As a result, the power factor stays above 0.9.

After installing PV systems, the large amount of power they generate lowers the power needed from the grid. At this point, the remaining reactive power from capacitor compensation becomes significant compared to the reduced active power consumption. When solar power generation is more than the load consumption, the grid's active power use drops to zero. Some reactive power controllers may not work well, which can raise reactive power and lower the power factor.

For sites with only PV generation, there is little active power use. Managing both the low-voltage side reactive power and the reactive power from the transformer is important. You must also manage the high-voltage side reactive power to ensure the power factor meets the required standards.

 

Solution

To address the low power factor at PV sites, it is essential to ensure complete reactive power management. We need a new device called the Static Var Generator (SVG) for managing reactive power.

SVG applies the most advanced power electronics and automatic control technologies. It connects in parallel to the grid. It uses current transformers to measure the system current in real-time.

It extracts the reactive component and creates a current of equal size but opposite phase. This cancels out the reactive current in the grid. This process achieves reactive power compensation.

SVG has a three-level structure with powerful IGBT power modules. This setup achieves a switching frequency of over 20 kHz.

This lets SVG quickly handle reactive power. It has a response time of under 5 ms and a compensation rate over 99%. This effectively solves reactive power problems at PV sites.

 

Field Application

For general site renovation projects, you can add an SVG module to the existing capacitor cabinet. This will help compensate for the remaining reactive current. It achieves the goal of reactive power compensation. The on-site wiring diagram is as follows:

  At this point, we need to pay attention to the position of the current transformers for SVG and the capacitor controller. Due to the fast response speed of SVG, the capacitor controller's sampling must not include SVG's current, while SVG's sampling current must include the capacitor's current to ensure SVG compensates for the remaining reactive current from the capacitor compensation.

 

  The capacity of the added SVG is generally configured based on the remaining reactive power on-site. This can be determined by checking the remaining reactive power on the reactive power controller or through on-site power quality testing. When selecting the SVG compensation capacity, some margin should be considered.

  For new projects, pure SVG modules can be used for reactive power compensation. The schematic diagram is as follows:

Application Case

Shanghai XX New Energy Technology Co., Ltd. is a comprehensive energy service company with extensive experience in energy-saving renovations, power engineering.

After installing a PV power generation system at a factory in Xi'an, the on-site power factor decreased, resulting in power penalties. 

To address the power penalties, a 200 kvar SVG reactive power compensation cabinet was installed to manage the low-voltage side reactive power. After the compensation, the power factor improved significantly, and no further power penalties occurred.

 Six months later, the user reported power penalties again. After communication, it was found that the user's load had completely stopped production, and the site had become a pure PV generation state with significantly reduced active power consumption. Even with complete compensation of the low-voltage side reactive power, the transformer itself generated reactive power, causing the high-voltage side power factor to remain below the required level.

To address the high-voltage side reactive power generated by the transformer, the on-site high-voltage side power quality was measured. Through analysis, the SVG compensation strategy was optimized to include high-voltage side reactive power compensation, effectively resolving the issue.

After the SVG optimization, the high-voltage side reactive power significantly decreased, and the power factor increased from 0.77 to 0.94, demonstrating excellent compensation results.

 

 

Product Introduction - Static Var Generator

Static Var Generator operates on voltage-type inverter principles using IGBT to generate reactive compensation currents that counteract grid reactive currents.

 

Advantages of SVG over traditional capacitor banks:

· Faster response (within 5ms)

· High precision (Power Factor > 0.99)

· Capable of both inductive and capacitive compensation

 

Key Features:

· Real-time bidirectional reactive compensation

· Harmonic filtering (2nd-25th order harmonics, 100% filtering of rated capacity)

· Fast response and high efficiency (>97.5%)

· Two bus current sampling signals, meeting different sampling requirements for the load side and power supply side, and are suitable for parallel operation of multiple devices, facilitating on-site construction requirements for new or renovation projects.

· Multiple protection mechanisms (overcurrent, overvoltage, overheating)

· Modular design for various installation methods

· Three RS485 signals, meeting communication interface requirements for on-site cabinet assembly and remote monitoring.

· The device has third-party test reports for salt spray, EMC, and simulated altitude tests, enabling it to adapt to various harsh environments.

 

Technical Specifications:

· Operating Voltage: AC 400V (-40% ~ +20%)

· Operating Frequency: 45Hz - 65Hz

· Response Time: ≤5ms

· Efficiency: ≥97.5%

· Harmonic Filtering Efficiency: ≥97%

· Reactive Power Compensation Efficiency: ≥99%

· Protection Level: IP30

· Operating Temperature: -35°C to 55°C

 

Contact us for expert guidance:

For more information on how our Active Harmonic Filter and Static Var Generator can help improve power quality: sales@intonepower.com

 

 

 

Keywords: grid stability, stability and reliability, voltage fluctuations, enhances grid, power factors

state of the art, voltage regulation, power quality issues, static var generators svgs

ensuring efficient, photovoltaic pv systems, power output