Zhang Shiquan Huang Linglin
Ankerui Electric Co., Ltd., Jiading, Shanghai 201801
Abstract: With the in-depth application of power electronics technology, the degree of automation in the petrochemical industry has been continuously improved, and the nature of the load has also undergone qualitative changes. The increase in nonlinear and impact loads has brought about voltage flicker, three-phase imbalance, and harmonics. A series of power quality problems, affecting the safe operation of the grid and reducing production capacity. Therefore, constantly optimizing and improving the power quality of the petrochemical industry is an important guarantee for the safe operation of the petrochemical industry.
Keywords: petrochemical industry, power quality, voltage flicker, harmonics
1 Introduction
With the implementation of a resource-saving and environment-friendly social strategy in China, the petrochemical industry is faced with more severe situations and tasks in resource guarantee, energy conservation, emission reduction and safe production. The production technology of the petrochemical industry is complex and the operating conditions are harsh. The power quality problem is also becoming increasingly serious. A serious carelessness in the power system may cause serious safety incidents. How to improve power quality is crucial for ensuring the safe and stable operation of power-using equipment, improving the comprehensive utilization efficiency of energy in the industry, reducing power network pollution, and implementing safe production.
2 Indicators for Measuring Power Quality in the Petrochemical Industry
The power quality indicators of the petrochemical industry are no different from other industries. However, due to the complexity of its own power grid system, its power quality requirements have become more demanding. The indicators for measuring the power quality of the petrochemical industry mainly include the following:
Voltage deviation index
The change of reactive load makes the voltage of the power system far away from its rated voltage, in which lamps such as motor and lighting are easily affected by voltage deviation.
Flicker and fluctuation of voltage
Caused by changes in active or reactive load caused by impact loads such as electric arc furnaces, arc welders, and rolling mills.
Harmonics of the power grid
The most fundamental cause of harmonic generation at non-linear loads. The abrupt changes in the voltage at the load and the current in the grid are all important factors that cause harmonics.
Three-phase voltage imbalance
The asymmetric load with large capacity and the harmonic components in the power grid system will cause the negative sequence component of the power grid, causing the main factor of unbalanced three phases.
3 Power Quality Analysis in Petrochemical Industry
The petrochemical industry has a long production line, extensive coverage, a high degree of automation, and complex inter-device correlation. Due to the need of production, there are a large number of rapidly changing impact loads, and the electrical load composition has also undergone qualitative changes. The access of a large number of non-linear loads inevitably generates many power problems: flicker and fluctuation of voltage, low power factor, excessive reactive power consumption, and harmonic interference. The problem of harmonic interference is the most concerned issue in the power quality of the petrochemical industry.
In the actual power supply system, due to the presence of a non-linear load, a non-sinusoidal current is formed when the current flows through a load that is not linearly related to the applied voltage. Abrupt changes in current and load terminal voltages can cause harmonics.
The main harmonic sources are: variable frequency speed control devices for pumps, uninterruptible power supply devices, soft-start motors, and new lighting fixtures (energy-saving lamps, fluorescent lamps using electronic ballasts).
Harmonic hazards in the power grid are embodied in the following aspects:
1) The harmonic pollution of the power grid, resulting in a relatively increase in loss of power transmission and distribution lines, motors, transformers, and thus increase the energy consumption;
2) The skin effect of wires and cables becomes larger, which accelerates the aging of insulation layers and reduces the utilization of cables;
3) The magnetic induction circulation of the iron core of the machine is increased, which increases the power consumption of the equipment and the life of the equipment is relatively shortened. In severe cases, the mechanical resonance occurs, the rotational speed of the motor is unstable, and the motor is burned;
4) The power system relay protection is erroneously started, trips by mistake, refuses to act and damage, often causes the accident or expands the blackout accident, threatens the safe reliable operation of the electric power system;
5) Loss of data in computers, data transmission and automatic control systems, distortion of display screens, malfunctions, component damage, and reduced accuracy of system file processing.
4 Ankerui Power Quality Management Solution
Ancorui is committed to the power industry for many years, has always been concerned about the petrochemical industry power quality issues, for the current status of the petrochemical industry power quality issues, to provide a feasible governance program for the petrochemical industry to promote the safe and stable operation of the petrochemical industry. Firstly, filter devices are set at the public power point to ensure that the harmonic content of the common bus of all levels of the grid is within the specified range; secondly, the harmonics of the power network at all levels are closely monitored and analyzed in a timely manner, and the control measures are formulated and implemented to ensure the petrochemical grid. The operating indicators meet the specification standards.
4.1 APMD Network Multifunction Instrument
APMD network multi-function instrument is mainly used in the instrument of high-pressure important circuit and low-voltage circuit. It has the function of power parameter measurement and power quality analysis. It can continuously monitor power quality in real time and save various fault information.
Instrument function:
â— Measurement function
The APMD network multi-function meter realizes the measurement of all power parameters, including real-time current, voltage, active power, reactive power, apparent power, frequency, and power factor.
â— Power quality analysis function
Voltage total harmonics, current total harmonics, 2-31 times voltage and current harmonics, voltage crest factor, telephone waveform factor, current K factor, voltage and current vector analysis, voltage and current imbalance analysis, voltage and current sequencing, Waveform tracking.
With RS485 communication interface, industrial Ethernet, Profibus and other interfaces to meet the needs of communication network management, centralized monitoring information upload, to meet the needs of real-time monitoring.
The continuous finishing production line of automation equipment in the petrochemical industry is extremely sensitive to disturbances in the distribution system. A fraction of a second of abnormal power supply may cause chaos in production, and its loss is difficult to estimate. Through the APMD network power meter to achieve real-time monitoring of power quality, issued an alarm or control instructions, take preventive measures to ensure the safe and effective operation of the petrochemical industry power system, so the need for continuous monitoring of power quality is self-evident.
4.2 ANAPF active filter device
ANAPF active power filter device can dynamically filter the harmonic current generated by the non-linear load in the power supply system, reduce the voltage harmonic distortion, and effectively eliminate the influence of harmonics on transformers, capacitors and precision equipment.
The principle of the ANAPF active filter device: Connected in parallel to the power grid, through the real-time monitoring of the harmonic and reactive components of the load, using PWM converter technology, generated from the converter and the current harmonic components and reactive components corresponding The reverse component is injected into the power system in real time, so that harmonic control and reactive power compensation are achieved.
4.2.1 Main Technical Features of ANAPF
â— A machine with multiple functions can compensate harmonics and compensate for reactive power.
â— DSP + FPGA all-digital control, with a very fast corresponding time;
â— It has perfect bridge arm over-current and protection function;
â— Advanced main circuit topology and control algorithm, high precision and stable operation.
4.2.2 Compensation Capacity Calculation
Harmonic currents can be estimated from the transformer capacity, taking into account the load factor of the transformer, which can be estimated based on the following formula:
K1 is the load ratio: that is, the ratio of the load to the rated capacity of the transformer, which is usually taken as 0.6 to 0.8, where 0.6 is taken;
K2 is the harmonic coefficient, and the centralized compensation field is suitable for occasions where the overall harmonic pollution is not high but scattered, taking 12%;
ST is the rated capacity of the transformer in kVA;
US is the low voltage system voltage, which generally takes 0.4.
According to the above formula, a transformer with a capacity of 2000 kVA has an output side harmonic current of ITHD=206 A. An active power filter cabinet with a harmonic compensation capacity of 200 A can be selected for compensation.
4.2.3 Compensation method
In the petrochemical industry's power supply system, ANAPF active power filter units can use three types of filter compensation.
â— Concentrated compensation on the outgoing side of the transformer
When the number of non-linear loads is large and the distribution is relatively decentralized, and the harmonic distortion ratio is not too high, an ANAPF active power filter device can be centrally installed on the low-voltage power distribution bus of transformers for centralized compensation, such as energy-saving lamps and gas. Discharge lamp more lighting load transformer. This compensation method can effectively improve the operating performance of the transformer and improve the overall power quality of the system.
Centralized compensation
â— Partial branch partial compensation
When the non-linear equipment is concentrated on certain specific branches, an ANAPF active filter device can be installed on the branch to perform local compensation.
Local compensation
â— Specific equipment on-site compensation
Single-capacity, stable-running non-linear petrochemical plants have non-linear loads with obvious spectral characteristics and low natural power factor, and the harmonics generated by harmonic sources are relatively concentrated in three or less consecutive groups (eg, three times, 5th, 7th) harmonics treatment, on-site compensation for harmonic sources, such as rectifier equipment, variable frequency equipment, welding equipment, etc., this method can achieve very good compensation and energy saving effect, will not be on the bypass And the entire system has an impact.
Local compensation
When designing a harmonic control solution, the above three kinds of harmonic control methods can be flexibly adopted according to the harmonic monitoring data of the distribution network, and the harmonic pollution of the petrochemical industry can be better managed to eliminate hidden dangers of the power supply system. Harmonic pollution minimizes the impact on the petrochemical industry's power grid systems and equipment and avoids affecting the normal operation of important equipment.
5 Conclusion
This article analyzes the power quality problems in the petrochemical industry and proposes that harmonics are one of the important indicators of power quality. Explained the management plan of Ankerui's power quality in the petrochemical industry, effectively solved the problem of actual electric energy, improved economic efficiency, and contributed to building a resource-saving society.
6, company profile
Ankerui Electric Co., Ltd. [Stock Code: 300286.SZ] is one of the few leading companies in China that provides system solutions such as smart power monitoring, power management, and electrical safety for smart grid customers.
Since its establishment in June 2003, the company has focused on the R&D, production and sales of customer-side smart power meters. The product line covers the low-voltage power signal acquisition, measurement, measurement, monitoring, protection and system integration of smart grid subscribers. Power meters, intelligent motor controllers, rail-mounted energy meters, power sensors, photovoltaic combiner boxes, active filters, medical clean power cabinets and other products as well as intelligent power monitoring and power management, building energy analysis management, electrical fire monitoring, Data center electricity monitoring, photovoltaic power plant monitoring, ZigBee (Internet of Things) radio energy management and other system solutions.
The company owns a Jiading district-level technology center and is a high-tech enterprise and a software company. He successively participated in GB/T22264-2008 "Installed Digital Electric Measuring Instrument", JB/T10736-2007 "Low Voltage Motor Protector", GB/T15576-2008 "Low Voltage Complete Reactive Power Compensation Device", GB/T22387-2008 "The Residual Current "Action relay" and many other electric power meter national standard and line standard drafting or preparation. As of December 2011, the company has more than 100 authorized patents and more than 70 computer software copyrights; ACR network power meters are listed as national key new products, and the company is listed as one of the key enterprises of the smart grid by the Shanghai Economic and Trade Commission.
In 2007, the company's production base in Jiangyin, Jiangsu was completed and put into production. The first-phase factory building area was 10,000 square meters. It was the first company in the smart power meter industry to adopt the lead-free SMT production technology and provided the industrialization and scale implementation of the company's products. Protection. In March 2010, the company's technical transformation, the workshop to carry out anti-static transformation, so that the production environment to further enhance, at the same time, the introduction of MES management system in production, each process bar code scanning, so that the entire production schedule and process have been controlled . Basically achieved paperless management, saving production costs and improving management efficiency.
Ankerui Trademarks and Products have been rated as Shanghai Famous Trademarks and Brand Named Products. The products are widely used in the Shanghai World Expo Project, the Guangzhou Asian Games Project, the National Stadium of Costa Rica, Beijing-Tianjin High-speed Rail Power Monitoring, Dunhuang 10MW Photovoltaic Demonstration Power Station, China Bank of Pudong Data Center, India 500,000 tons of coking and other major projects at home and abroad, won a good reputation in the market.
references
[1] Ancorui Electric Co., Ltd. Product Manual. 2013.01.
[2] Factors Affecting Power Quality and Improvement Methods, Chen Lei. Shanghai: 2008.
Article Source: "Electrical Technology" No. 1 of 2014
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