Experience with new large adjustable speed drive technology for multiple synchronous motors

Voltage source Inverter (VSI) technology, suitable for synchronous motor applications, now exists with high power ratings producing high output voltage (≥11kV) with significant benefits over the widely used load commutated inverter (LCI) drives. The paper covers an existing VSI technology applied for the first time at a higher operating voltage. This 15.5 MW, 11 kV VSI Adjustable Speed Drive (ASD) installation is used to soft start three synchronous motors and speed control of one of these for a process gas compressor application. Challenges faced during commissioning are described and associated solutions are presented. A failure analysis of the ASD during commissioning is presented. An ASD design review was undertaken which has resulted in an improved alternative to the conventional HV busbar design. A protection co-ordination study incorporating incoming switchgear and internal drive protection functions is presented. Improved protection schemes and settings are described to obtain faster coordinated fault clearance and improved ASD availability. The paper provides operating experience since the modified ASD was placed in service in January 2006. Key recommendations are made to enhance the reliability, availability and performance of medium voltage drive systems. Also, suggestions are made for additions to the 2006 IEEE 1566 medium voltage ASD standard.Index Terms -High power rating adjustable speed drive, medium voltage, voltage source inverter, failure analysis, protection, reliability, availability.

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“…The gathered field data and measurements show the ASD input and output waveform are near sinusoidal with very high input power factor [12], [13].…”

Section: Success Of Modification and Operating Experiencementioning

confidence: 96%

Ensuring availability of a large Adjustable Speed Drive for process gas compressor application rated 11 kV, 15.5 MW (20778 hp)

Endrejat

Hanna²,

Shultz

2009

2009 Record of Conference Papers - Industry Applications Society 56th Annual Petruleum and Chemical Industry Conference

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“…This removed the requirement for any additional front-end or load side modifications or additions [10], [11]. Nevertheless, new multilevel VSI technologies are available to address all the disadvantages and, most importantly, to obtain highoutput voltages (11 kV) without a step-up transformer, e.g., the VSI-H type with a detailed comparison with the LCI technology in [12].…”

Section: Technology Overviewmentioning

confidence: 99%

“…New reduced certification requirements may be applicable for certain MV technologies because of more sinusoidal output waveforms [15]. Some important factors that must still be evaluated are given in [12], [15], and [16].…”

Section: Hazardous Area Considerationsmentioning

confidence: 99%

The soft starters

Endrejat

Pillay

2008

IEEE Ind. Appl. Mag.

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ARGE PUMPS AND COMPRESSORS IN THE MEGA-watt range are often required by the petrochemical industry. The associated motors are often large enough for soft starting or may also be so large to dictate the requirement of soft starting. Soft starting may also be required because of the nature of the process or the driven equipment. Direct online (DOL) starting results in the severe transients in the machine and associated power system, which can be avoided by soft starting. One or more large drives in a process plant can often benefit from the adjustable-speed operation for improved process control or energy savings. The reliability of the process is, however, extremely important because outages frequently result in major production or financial losses. Therefore, a reliable, flexible, safe, and cost-effective system is required.

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“…This paper describes on-site measurements and simulations investigating the possibility of unacceptable overvoltages. The application configuration of the system is described in [8] and [11]. A synchronization, desynchronization, and process control scheme is applied to improve process availability (to synchronize the adjustable-speed-driven motor before certain drive trip conditions) and also to facilitate soft starting of other motors.…”

Section: Introductionmentioning

confidence: 99%

“…This is also referred to as a bypass configuration. Further explanation for bypass configurations and current limitation during synchronization is described in [3], [11], and [14]. It is important to evaluate the effect of the rather uncommon synchronization reactor (normally not used with ASDs without a bypass configuration).…”

Section: Introductionmentioning

confidence: 99%

Resonance Overvoltages in Medium-Voltage Multilevel Drive Systems

Endrejat

Pillay

2009

IEEE Trans. on Ind. Applicat.

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Simulations and field tests indicate that unacceptable motor-terminal overvoltages and waveform shapes can occur in the normal operating range with high-output-voltage multilevel drive systems. These waveforms (if unattended) can result in premature motor insulation failures. A case study of an 11-kV multilevel system is presented. Simulations and calculations confirm the theory of resonance overvoltages. Different solution possibilities are analyzed. Further simulations and investigations are performed to determine the optimal carrier frequency. Test results confirm that the proposed modification has the desired effect, with waveforms well within limits stipulated by international standards. Simplified equations and recommendations are provided to determine suitable application solutions. Further simulated resonance case studies are presented, considering the effect of the system configurations, motor size, and cable length. Suitable carrier-frequency selection methods are presented to solve the problem.

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Experience with new large adjustable speed drive technology for multiple synchronous motors

Cited by 8 publications

References 38 publications

Ensuring availability of a large Adjustable Speed Drive for process gas compressor application rated 11 kV, 15.5 MW (20778 hp)

Ensuring availability of a large Adjustable Speed Drive for process gas compressor application rated 11 kV, 15.5 MW (20778 hp)

The soft starters

Resonance Overvoltages in Medium-Voltage Multilevel Drive Systems

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