Abstract: This paper introduces the function, software, and application of motor protectors in the control system of submersible electric pumps in oilfields, and explains the necessity of applying motor protectors to submersible electric pumps.
Keywords: Intelligent protector, function, oilfield submersible pump, application
1 Introduction
With the development of my country's petroleum industry and the needs of oilfield development, mechanical oil recovery methods are an important step in the entire oilfield development process in order to improve oil production speed and ultimate recovery rate. Submersible electric pumps (SAPs), as an important type of mechanical oil recovery equipment, are playing an increasingly important role in oilfield exploitation.
The submersible electric pump (SAP) control system consists of a SSP control cabinet, a GPRS transceiver, and monitoring software. The SSP control cabinet is used for controlling SSPs in oilfields, supplying power to SSPs with AC frequencies of 50Hz and 60Hz, voltages from 380 to 2500V, and currents up to 200A. Its core component is the SSP intelligent protector. The GPRS transceiver is used to upload electrical parameters measured by the SSP control cabinet and process parameters from other instruments to the control system. The monitoring software is used for HMI operation.
2. Intelligent Protector
Intelligent protectors provide protection, measurement, and control functions for submersible electric pumps. Acrel's ARD3T motor protector is a dedicated protection product for submersible electric pumps. The ARD3T product includes a main module, measurement module, digital input module, analog input module, temperature module, and communication module, and is equipped with a touch screen for real-time display of measurement and protection parameters.
ARD3T Submersible Pump Intelligent Protector
2.1 Measurement Function
The intelligent protector, in conjunction with a protective current transformer, enables three-phase current measurement and real-time display of current curves. The current transformer can withstand overloads up to 10 times. Three-phase voltage measurement and real-time voltage curve display can be achieved via an external transformer. The multipliers of the current and voltage transformers within the protector can be arbitrarily set according to actual parameters. Simultaneously, the protector can measure frequency and power and statistically analyze the consumed electrical energy. A temperature sensor can measure the temperature of the submersible pump. These parameters provide a basis for the protection of the submersible pump.
2.2 Protection Functions
Submersible electric pumps (SAPs) used in oilfields have a high failure rate due to their working environment and other factors. Traditional protection devices generally cannot effectively protect the motor when it malfunctions, often leading to motor and pump burnout and production shutdowns. The ARD3T intelligent protector is designed based on the current status of SSPs in Chinese oilfields and the actual production needs of oil wells. It provides comprehensive protection for the pump. It can detect and control the motor's operating status, preventing damage caused by abnormal operation.
2.2.1 Overload Protection
There are many reasons for submersible electric pump (SEP) overload, including protector failure or improper cable head structure causing well fluid to enter the motor; damage to the motor insulation due to frequent voltage fluctuations and pump start-up and shutdown; sand production leading to prolonged high-load operation, causing excessive operating current and high temperature in the cable core, damaging the insulation; damage to the submersible cable during downhole operations; pump jamming due to sand or impurities, etc. All these causes ultimately manifest as excessive operating current. Under overload conditions, if the motor operates beyond its rated current for an extended period, it will overheat, its insulation will deteriorate, and it will burn out. The protector calculates the motor's heat capacity based on its heating characteristics and simulates the motor's heating characteristics to protect it. The overload protection delay time decreases inversely with increasing overload multiple.
Overload protection current-time comparison table
Overload characteristic curve
2.2.2 Underload Protection
When the motor is connected to a pump-type load, no-load or underload operation of the motor can be hazardous, and the protector provides underload protection. The main causes of underload in submersible electric pumps include tubing puncture, leaking drain valves, and leakage in the sand setter pipe leading to tubing loss; poor formation fluid supply and insufficient fluid supply due to foreign matter blockage in the sand screen pipe; sand blockage or mud blockage in the pump or tubing; and broken pump shaft or separator shaft, etc. When the percentage of the three-phase average current to the rated current is lower than the underload setting value, the protector will operate within the set time (delay). The delay time of the underload protection decreases inversely as the current underload multiple increases.
magnification | Tripping time (s) |
1 | 60 |
0.9 | 49.59 |
0.83 | 41.67 |
0.67 | 26.67 |
0.5 | quick break |
Underload Protection Action Time Reference Table
Underload characteristic curve
2.2.3 Other functions
The product also features inverse-time protection functions such as current imbalance, overvoltage, undervoltage, and voltage imbalance; time-limit protection functions such as phase loss, locked rotor, blockage, and external faults; current history data export and voltage history data export functions; customer attendance function; fault recording function; and parameters are not lost when power is off.
2.3 Technical Parameters
Technical parameters | Indicators | ||
Submersible electric pump operating power supply | 380 to 2500V | ||
frequency | 50Hz, 60Hz | ||
ARD3T Auxiliary Power Supply | AC/DC 110 / 220V, power consumption ≤15VA | ||
Touchscreen auxiliary power supply | DC 24V | ||
Rated operating current of motor | 6.3 (1.2A-3150A) | External current transformer + measurement module CT and PT settings are available. | |
leakage current | 50mA-1A | Utilizing a measurement module + leakage current transformer | |
3A-30A | |||
Relay output contact capacity | resistive load | AC250V, 6A; DC24V, 6A | |
Inductive load | AC250V, 2A; DC24V, 2A | ||
Main switch inputs and outputs | 4DI, 4DO, where DI can be a dry node or a wet node. | ||
Switching module | 4DI, 3DO, where DI can be a dry node or a wet node. | ||
Temperature module | External sensor types: PT100, PT1000, Cu50, PTC, NTC Number of sensor channels: 3 Sensor measurement range: PT100/PT1000: -50°C～+500°C Cu50: -50°C to +150°C PTC/NTC: 100Ω～30kΩ | ||
Analog module | It can realize: 2-channel 4-20mA input measurement, 2-channel 4-20mA transmitter output. Measurement accuracy ±0.5% with 4-20mA input. The maximum load capacity of the 4-20mA output is ≤500Ω. | ||
Main Communication | RS485: Modbus-RTU | ||
Communication module | RS485: Dual Modbus-RTU, Profibus | ||
environment | Operating temperature | -10ºC～55ºC | |
Storage temperature | -25ºC～65ºC | ||
relative humidity | ≤95% non-condensing, no corrosive gases | ||
altitude | ≤2000m | ||
Pollution level | Level 3 | ||
Protection level | Main unit IP20, split display module IP45 (mounted on the cabinet) | ||
Installation Category | Level III | ||
The touchscreen uses Kunlun Tongtai products and is equipped with dedicated software to display the operating status of the electric pump in real time, making it convenient for maintenance personnel to observe and understand the working status of the electric pump on site.
Software interface:
Main interface: Real-time current curve
Real-time voltage curve event log
4. Structure diagram of submersible electric pump control system
5 Conclusion
This article introduces the functions and monitoring interface of the motor protector for submersible electric pumps in Ankerui oilfields. Using this integrated protector can reduce electrical faults during motor operation, detect and control the motor's operating status, and prevent damage to the motor caused by abnormal operation.
6. Company Profile
Acrel Electric Co., Ltd. [Stock Code: 300286.SZ] is one of the few leading domestic companies that provides intelligent power monitoring, power management, and electrical safety system solutions for smart grid users.
Since its establishment in June 2003, the company has focused on the research, development, production and sales of smart power meters for users. Its product line covers low-voltage power signal acquisition, measurement, metering, monitoring, protection and system integration for smart grid users. The main products include network power meters, smart motor controllers, DIN rail mounted energy meters, power sensors, photovoltaic combiner boxes, active filters, medical cleanroom power cabinets and other products, as well as system solutions such as smart power monitoring and energy management, building energy consumption analysis and management, electrical fire monitoring, data center power monitoring, photovoltaic power station monitoring, and ZigBee (Internet of Things) wireless power management.
The company possesses a Jiading District-level technology center and is a high-tech enterprise and software enterprise. It has participated in the drafting or compilation of several national and industry standards for power meters, including GB/T22264-2008 "Installation-type Digital Electrical Measuring Instruments", JB/T10736-2007 "Low-voltage Motor Protectors", GB/T15576-2008 "Low-voltage Complete Reactive Power Compensation Devices", and GB/T22387-2008 "Residual Current Operated Relays". As of December 2011, the company held over 100 authorized patents and over 70 computer software copyrights; its ACR network power meter was listed as a national key new product, and the company was designated as one of the key smart grid enterprises by the Shanghai Municipal Commission of Economy and Information Technology.
In 2007, the company's production base in Jiangyin, Jiangsu Province, was completed and put into operation. The first phase of the factory covered an area of 10,000 square meters and was the first enterprise in the intelligent power meter industry to adopt lead-free SMT production technology, providing a guarantee for the industrialization and large-scale implementation of the company's products. In March 2010, the company underwent technological upgrades, including anti-static renovations to the workshop, further improving the production environment. Simultaneously, an MES management system was introduced, with barcode scanning at each stage of the process, enabling control over the entire production progress and process. This essentially achieved paperless management, saving production costs and improving management efficiency.
Ankerui's trademarks and products have been recognized as famous trademarks and brand-name products in Shanghai. Its products have been widely used in major domestic and international projects such as the Shanghai World Expo, the Guangzhou Asian Games, the Costa Rica National Stadium, the Beijing-Tianjin High-Speed Railway power monitoring, the Dunhuang 10MW photovoltaic demonstration power station, the Bank of China Pudong Data Center, and the India 500,000-ton coking plant, winning a good market reputation.
References:
Acrel Electric Co., Ltd. Sample Materials
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