CC BY
2УДК 621.314.26
Stepanov M.
master's degree Chuvash State University (Cheboksary, Russia)
IMPACT OF EFFICIENT USE OF FREQUENCY CONVERTERS ON REDUCING INDUSTRIAL ENERGY CONSUMPTION
Аннотация: article investigates the impact of efficient use offrequency converters (FC) on reducing industrial energy consumption. It provides a technological overview and examines the types of FC and their applications in various industries. Technological advancements in the field, such as improvements in power electronics, control algorithms, and materials, are reviewed. The benefits of these innovations in enhancing energy efficiency are highlighted.
Ключевые слова: frequency converters, energy consumption, power electronics, control algorithms, sustainable development, technological advancements.
Introduction.
In the contemporary world, the issue of energy efficiency is becoming increasingly pertinent, particularly within industrial contexts, where energy consumption plays a pivotal role in economic viability and environmental sustainability. One significant tool for enhancing energy efficiency in industrial settings is the utilization of frequency converters (FC). These devices enable the regulation of motor speeds, thereby leading to substantial energy savings by aligning production with actual demand.
The aim of this study is to investigate the impact of effective frequency converter utilization on reducing energy consumption in industrial operations.
Main part. Technological overview of FC.
FC, also known as variable frequency drives (VFDs) or inverters, are electronic devices used to control the speed and torque of alternating current (AC) motors by varying the frequency and voltage of the power supplied to the motor. These devices play a crucial role in industrial applications where precise control over motor speed is required to optimize energy usage and improve process efficiency.
The principle behind the operation of FC lies in the conversion of fixed-frequency AC power from the mains supply into variable-frequency AC power suitable for driving induction or synchronous motors. This is achieved through a series of electronic components, including rectifiers, DC link capacitors, insulated-gate bipolar transistors (IGBTs), and pulse-width modulation (PWM) techniques (figurel).
1С и
Uy
Figure 1. Example of a FC circuit: Inv - inverter, ICU - inverter control unit, AM -asynchronous motor, Uc, U1 - voltage, fs, f1- frequency, Uy - control signal [1].
FC offer several advantages in industrial settings:
• They allow for soft starting and stopping of motors, reducing mechanical stress and wear on equipment, which extends the lifespan of machinery and reduces maintenance costs.
• By controlling motor speed to match process requirements, FC facilitate energy savings by eliminating the need for mechanical throttling devices such as valves or dampers, which dissipate energy as heat.
• Converters enable precise control over motor speed and torque, allowing for optimization of process parameters such as flow rate, pressure, or temperature. This
level of control enhances process efficiency and quality, leading to improved productivity and product consistency.
Advancements in frequency converter technology have led to the development of more efficient and compact devices with enhanced features such as regenerative braking capabilities, sensorless vector control, and integrated communication interfaces for seamless integration into industrial automation systems. These developments have further expanded the applicability of FC across a wide range of industrial sectors, from manufacturing and materials handling to HVAC (heating, ventilation, and air conditioning) systems and renewable energy applications. FC represent a key technology for achieving energy efficiency and process optimization in industrial environments. Their ability to regulate motor speed and torque with precision offers significant benefits in terms of energy savings, equipment longevity, and process performance, making them indispensable tools for modern industrial operations.
Types of FC and their application in industry for energy consumption reduction.
FC are critical components in modern industrial applications, enabling the precise control of motor speed and torque. This capability allows industries to optimize their processes, leading to significant energy savings. Various types of FC are used across different industrial applications, each with specific features and advantages.
Voltage source inverter (VSI) drives are the most common type of VFD used in industrial applications. These drives convert a fixed-frequency, fixed-voltage input to a variable-frequency, variable-voltage output [2]. VSI drives are known for their simplicity, reliability, and efficiency. They are widely used in applications such as:
• Pumps and fans: by adjusting the motor speed to match the required load, VSI drives help in reducing energy consumption, especially in HVAC systems where airflow or fluid flow needs to be regulated.
• Conveyors: in manufacturing and material handling, controlling the speed of conveyors can optimize the production process, leading to reduced energy usage.
Current source inverter (CSI) drives are another type of frequency converter that, unlike VSI drives, utilize a current source instead of a voltage source. CSI drives
are known for their robustness and are typically used in high-power applications. Their applications include:
• Large pumping systems: CSI drives are effective in large-scale water supply and wastewater treatment plants, where they contribute to significant energy savings by optimizing pump operations.
• Mining and metallurgy:the ability to handle high-power loads makes CSI drives suitable for heavy-duty applications such as crushers, mills, and hoists in mining operations.
Pulse width modulation (PWM) drives are a type of VSI drive that uses a sophisticated switching technique to control the motor's voltage and frequency with high precision [3]. PWM drives offer high performance and efficiency, making them suitable for applications such as:
• Precision machining: in industries like automotive and aerospace, PWM drives enable precise control of machine tools, enhancing productivity and reducing energy waste.
• Textile manufacturing: the textile industry benefits from PWM drives through improved control over spinning and weaving machines, leading to better energy management and product quality.
Direct torque control (DTC) drives are advanced FC that provide highperformance control by directly regulating motor torque and flux. This method offers rapid response and high accuracy, suitable for applications requiring precise torque control. DTC drives are commonly used in:
• Paper and pulp industry: for processes such as paper machine drives and pulp processing, where precise control of motor speed and torque can significantly enhance energy efficiency.
• Wind turbines: DTC drives help in optimizing the performance of wind turbines, ensuring maximum energy capture and efficient operation under varying wind conditions.
Sensorless vector control (SVC) drives combine the benefits of traditional VFDs with advanced control algorithms that do not require feedback from a physical
sensor. SVC drives are suitable for applications where sensor installation is challenging or cost-prohibitive. Applications include:
• Centrifugal pumps and compressors: in industries like oil and gas, SVC drives optimize the operation of centrifugal pumps and compressors, leading to substantial energy savings.
• HVAC Systems: for large commercial buildings and industrial facilities, SVC drives improve the efficiency of heating, ventilation, and air conditioning systems by ensuring motors run at optimal speeds.
The effective use of various types of FC in industrial applications is a key strategy for reducing energy consumption. By tailoring the type of frequency converter to the specific requirements of each application, industries can achieve significant energy savings, improve process control, and enhance overall operational efficiency.
The practice of using FC in industry.
The use of FC in industrial settings provides significant energy-saving benefits, especially in energy-intensive industries such as oil and gas extraction. FC enable precise control of motor speed and torque, allowing processes to be optimized for energy efficiency and reducing unnecessary power consumption.
One of the primary advantages of FC is their ability to match motor speed to the specific demands of the process. This capability is particularly beneficial in applications such as pumps and compressors, which are common in the oil and gas industry. By adjusting the speed of these machines to the actual process requirements, FC can eliminate the inefficiencies associated with fixed-speed operation and mechanical throttling devices, which often lead to excessive energy consumption.
A notable example of energy savings achieved through the use of FC is found in the operations of BP, a global leader in the oil and gas industry. BP implemented VFDs across several of its extraction and processing facilities. According to a report by BP, the installation of VFDs on large pump motors at their refinery in Rotterdam resulted in energy savings, leading to significant reductions in both operational costs and greenhouse gas emissions. The frequency-controlled drive mounted on gas turbines has an energy efficiency of 94.5%, which reduces energy costs [4].
Another example is Equinor, which has incorporated FC into its operations to enhance energy efficiency. Equinor's application of VFDs in their offshore oil platforms has led to a reduction in energy consumption. This improvement was particularly noted in compressor applications, where the ability to regulate motor speed based on real-time process demands significantly decreased energy wastage. Thanks to the introduction of new electrification technologies at the Johan Sverdrup field, CO2 emissions are 0.67 kg per barrel, compared with an average of 9 kg. By 2040, the company plans to reduce emissions by 70%, which will be achieved, among other things, by improving energy efficiency [5].
Similarly, Shell has leveraged frequency converter technology to optimize energy use in its upstream operations. In one of its offshore oil platforms, the implementation of VFDs on electric submersible pumps (ESPs) resulted reduction in energy consumption. This enhancement not only decreased the operational costs but also extended the lifespan of the equipment by reducing mechanical stress and wear. The Vita deepwater platform in the Gulf of Mexico is one of the company's newest platforms, with maximum production of 100,000 barrels of oil equivalent per day. During its lifetime, the platform is expected to reduce carbon dioxide (CO2) emissions by about 80% compared to its original design. In addition to reducing emissions, Vito reduces operating costs by 70% more than originally planned. This is an example of improving energy efficiency with lower emissions through the introduction of new technologies [6].
The deployment of FC in the oil and gas industry exemplifies the substantial energy-saving benefits that can be achieved through this technology. Examples from companies like BP, Equinor, Shell, and Hess Corporation demonstrate the effectiveness of VFDs in optimizing motor operations, reducing energy consumption, and contributing to overall sustainability goals. The consistent energy savings observed across various applications underscore the importance of adopting frequency converter technology to enhance energy efficiency in industrial processes.
Features of implementing FC in industry.
Implementing FC in industrial settings involves a comprehensive understanding of the technical, economic, and operational aspects that influence their successful integration (table 1).
Table 1. Key aspects of FC implementation [7,8].
Aspect Description Challenges Solutions
Technical requirements Detailed assessment of electrical and mechanical system compatibility Integration with existing systems, potential need for system upgrades Conduct thorough site surveys, customize solutions to match system specifications
Economic considerations Evaluation of initial investment versus long-term energy savings High upfront costs, uncertain return on investment Perform cost-benefit analysis, consider financing options, use energy savings to justify investment
Operational impact Analysis of how FC affect daily operations and maintenance Disruption during installation, need for staff training Plan installations during downtime, provide comprehensive training programs
Regulatory compliance Ensuring adherence to industry standards and local regulations Navigating complex regulatory environments, meeting safety standards Engage with regulatory experts, ensure all equipment is certified and compliant
Monitoring and control Implementation of monitoring systems for ongoing performance evaluation Complexity of integrating monitoring systems, ensuring data accuracy Use advanced monitoring technologies, establish regular maintenance and calibration schedules
From the author's perspective, the successful implementation of FC in industrial settings hinges on a balanced approach that addresses both the technical and economic challenges while minimizing operational disruptions. The experience of companies like Siemens and ABB, which have pioneered the use of FC, underscores the importance of thorough planning and customization to meet specific industrial needs. These companies have demonstrated that with proper investment in site surveys, training, and monitoring systems, the initial high costs can be offset by substantial long-term energy savings and enhanced operational efficiency. While the integration of FC may present several challenges, the benefits they offer in terms of energy efficiency and process optimization are undeniable.
Technological advances and energy efficiency in FC.
The field of FC, or VFDs, has seen substantial technological advancements that significantly enhance their energy efficiency and performance in industrial applications. These innovations span across power electronics, control algorithms, and materials, driving the evolution of VFDs into more efficient and versatile tools for energy management.
Innovations such as Silicon Carbide (SiC) and Gallium Nitride (GaN) semiconductors have superior electrical properties compared to traditional silicon. SiC and GaN semiconductors allow for higher switching frequencies, reduced switching losses, and improved thermal performance. This leads to more compact, efficient, and reliable FC. Additionally, the latest generation of advanced Insulated Gate Bipolar Transistor (IGBT) modules offers lower conduction and switching losses, higher current densities, and better thermal management, translating to enhanced overall efficiency and reduced cooling requirements [9].
Model predictive control (MPC) algorithms use mathematical models to predict future system behavior and optimize control actions accordingly, providing better dynamic performance and efficiency compared to traditional control methods, particularly in complex and variable-load applications. SVC technology eliminates the need for physical sensors by using sophisticated algorithms to estimate motor parameters in real-time, improving the reliability and robustness of VFDs while
reducing maintenance costs and enhancing energy efficiency. DTC offers direct and precise control of motor torque and flux, providing fast dynamic response and high efficiency by minimizing switching losses and maximizing torque per ampere, contributing to significant energy savings in various industrial processes.
New magnetic materials with lower core losses and higher saturation flux densities improve the performance of inductors and transformers in VFDs, contributing to reduced energy losses and more compact designs. Improved thermal interface materials (TIMs) and heat sink technologies enhance the thermal performance of VFDs, as effective thermal management is crucial for maintaining efficiency and reliability, particularly in high-power applications.
The integration of these technological advancements in FC has led to substantial improvements in energy efficiency. Modern VFDs can achieve efficiency levels exceeding 95%, significantly reducing energy consumption in industrial applications. The benefits include reduced energy losses due to enhanced power electronics and control algorithms, optimized motor performance ensuring that motors operate at their optimal efficiency points, and lower cooling requirements due to improved thermal management. These advancements enable industries to achieve substantial energy savings, reduce operational costs, and improve process control.
Conclusions.
Efficient use of FC plays a crucial role in reducing industrial energy consumption. By optimizing motor performance and minimizing energy losses, these technologies contribute significantly to operational cost savings and improved process control. The advancements in power electronics, control algorithms, and materials have further enhanced the performance and reliability of FC, making them indispensable in modern industrial applications.
Achieving sustainable development goals requires a focus on energy efficiency and reduction of emissions. FC are a key component in this effort, helping industries lower their carbon footprint and comply with environmental regulations. Continued innovation and adoption of advanced frequency converter technologies are essential for promoting sustainable industrial practices and achieving long-term energy savings.
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