In Iraq—a land ravaged by war and riddled with scars—countless Chinese engineers, like courageous pioneers forging ahead against the tide, are passionately devoted to technology and tenaciously striving in high-risk, complex environments. They have braved countless mountains and rivers, bringing advanced equipment and cutting-edge technologies to take root here, contributing China’s strength to Iraq’s reconstruction.

STEP is also on this list. For over two decades, the company has been meticulously cultivating the fields of power electronics and motor control, continuously delivering green energy to the world. With high standards, high quality, and high efficiency, STEP drives the construction of major projects in key international markets, earning the deep trust of its customers.

Streets of Basra, Iraq

Crude Oil Central Processing Project

This project involves a central crude oil processing facility in a certain district of Iraq, aimed at building a central crude oil processing plant with a daily capacity of 100,000 barrels. A total of seven new-time high-voltage variable frequency drives (VFDs) have been deployed for this project, including five VFDs for compressor loads and two for oil pumps. This application showcases the on-site use of high-voltage VFDs to drive propane compressors, enabling seamless switching without any interruption. The VFDs employ advanced synchronous switching technology, ensuring rapid startup and smooth, seamless transition to mains-frequency operation.

Project site photo

Propylene Compressor Process Description

The propane compressor generates cooling capacity to cool natural gas by utilizing the endothermic effect of propane vaporization. The operational process is as follows:

The liquid propane from the propane buffer tank is cooled down by heat exchange in an economizer, then further throttled to lower its temperature. After exchanging heat with natural gas, the liquid propane evaporates into gaseous propane (with an evaporation temperature of -10°C), which then enters the propane suction tank. After being separated in the suction tank to remove any entrained droplets, the propane is compressed to 1.2 MPa by a propane compressor. It is then condensed into liquid propane (at 1.15 MPa and 30°C) in the propane aftercooler before returning to the propane buffer tank.

Propane Compressor and Motor

The characteristic of inverter-based reactive power synchronous switching.

Good harmonic filtering characteristics

The addition of an inductor provides excellent harmonic filtering performance, effectively absorbing and suppressing the higher-order harmonics generated by the frequency converter. This reduces harmonic interference on the motor and other equipment, making the output current closer to a sine wave. Moreover, when switching from variable frequency operation to power-frequency operation, the phase angle and amplitude are locked with greater precision.

The switching process is smooth.

By employing a sophisticated yet highly efficient control algorithm, the system can precisely detect and adjust the phase difference between the inverter and the motor, ensuring phase alignment at the moment of switching and enabling a smooth transition. This prevents voltage and current fluctuations caused by sudden phase shifts. In conjunction with the reactor, the system responds rapidly to changes in current during the switching process, quickly suppressing the rate of current rise and fall. As a result, the output current stabilizes within an extremely short time, guaranteeing a seamless switching operation.

Adaptive adjustment and rapid dynamic response

The compressor is equipped with a three-phase induction motor featuring a squirrel-cage rotor. This type of motor is characterized by a high starting current at low speeds and relatively low torque response. To address these characteristics, the inverter employs a starting torque-holding function that dynamically adjusts according to the load conditions, rapidly establishing excitation and driving the motor to its rated frequency. The highly reliable control algorithm has been extensively validated through numerous experiments and real-world applications, demonstrating exceptional reliability and stability. At the customer’s request, we conducted 16 switching operations under various conditions—no-load on-site, simulated industrial-load tests, and actual-load conditions—and each switching operation was performed smoothly and without issue. Furthermore, the system was successfully put into operation on the customer’s scheduled commissioning date.

STEP High-Voltage Inverter AS800 G3 Series Unit

Technical advantages of STEP variable-frequency synchronous switching technology

Reduce mechanical impact

Avoid the large current surge that occurs when switching from variable frequency to power frequency. Since such current surges can damage equipment such as inverters and motors, synchronous switching can effectively protect the equipment and extend its service life.

Fast and accurate phase matching

It reduces voltage fluctuations and transients during the switching process. By installing an output reactor, the output current waveform is improved, and harmonic interference to both the motor and the power grid is reduced. This helps maintain the overall stability of the power grid and is particularly well-suited for factory environments where multiple large-scale devices operate simultaneously.

STEP AS800 Inverter Equipment

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STEP AS 800 Inverter Product Information

Those advanced energy facilities gleam with a metallic sheen in the desert. Like colossal steel behemoths, they stand firmly on the vast expanse of land, starkly contrasting with the harsh local environment. These facilities embody the wisdom and sense of responsibility of Chinese engineers, showcasing China’s formidable technological prowess and highlighting the rise of Chinese national brands, which now shine brightly across the globe.

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