MV inverter selection guide
Tags: inverter, Medium voltage inverter
Power plant should consider reliability, economy, applicability and environment protection:
Reliability
1) Reliability of components: LV is better than MV. Mature product is better than the immature. For the same component, the better can be chosen according to the brand and class.
2) Reliability of main circuit structure: for the requirement of reducing waste of transmitting power, most big capacity motors are medium voltage motor. Voltage class is most 6kV and 10kV.
There are several modes for inverter to output medium voltage. For high-high mode, the reliability of power cells seriers-connecting is better than direct-connecting of components. Medium-low mode or medium-low-medium mode is only temporary solution in development and they should disappear in market. Some experts believe motors of 1.7 kV, 2.3 kV, 3.3 kV, 4.16 kV should be researched or change connecting mode of motor coil and add a transformer ahead of inverter to match inverter, which acts in a procrustean way.
3) Reliability during operation: power plant has following requirements for inverter to ensure generator units safefy: continue derating operation with several cells broken; can be transferred to direct on line state when inverter is broken; inverter does not stop during instant power-fault; equip UPS for controller; power source of 380V fan is supplied by inverter.
Economic
Economic can be discussed from price, spare cost, maintenance cost and product benefit. After-sale service is good and high effective because of self-research & manufacture, which reduces maintenance cost and protects user's investment to meet power plant requirement at maximum.
Meanwhile, MV inverter technology characteristics can also influence economy. For inverter with harmonic filter or power factor compensator, its efficiency and reliability must be low and operation time is short; for inverter equipped special motor, no capability of interchaning of motor; for inverter without cell-bypass function or no function of bypass to direct on line, MTBF is reduced greatly. These result in low efficiency of whole units.
Applicability
MV inverter should adapt power grid fluctuation including bus low voltage and short time bus voltage failure. Inverter also implements soft-start, soft-brake and intellectual speed-adjusting during frequent start/stop and high/low load changing.
Reliability
1) Reliability of components: LV is better than MV. Mature product is better than the immature. For the same component, the better can be chosen according to the brand and class.
2) Reliability of main circuit structure: for the requirement of reducing waste of transmitting power, most big capacity motors are medium voltage motor. Voltage class is most 6kV and 10kV.
There are several modes for inverter to output medium voltage. For high-high mode, the reliability of power cells seriers-connecting is better than direct-connecting of components. Medium-low mode or medium-low-medium mode is only temporary solution in development and they should disappear in market. Some experts believe motors of 1.7 kV, 2.3 kV, 3.3 kV, 4.16 kV should be researched or change connecting mode of motor coil and add a transformer ahead of inverter to match inverter, which acts in a procrustean way.
3) Reliability during operation: power plant has following requirements for inverter to ensure generator units safefy: continue derating operation with several cells broken; can be transferred to direct on line state when inverter is broken; inverter does not stop during instant power-fault; equip UPS for controller; power source of 380V fan is supplied by inverter.
Economic
Economic can be discussed from price, spare cost, maintenance cost and product benefit. After-sale service is good and high effective because of self-research & manufacture, which reduces maintenance cost and protects user's investment to meet power plant requirement at maximum.
Meanwhile, MV inverter technology characteristics can also influence economy. For inverter with harmonic filter or power factor compensator, its efficiency and reliability must be low and operation time is short; for inverter equipped special motor, no capability of interchaning of motor; for inverter without cell-bypass function or no function of bypass to direct on line, MTBF is reduced greatly. These result in low efficiency of whole units.
Applicability
MV inverter should adapt power grid fluctuation including bus low voltage and short time bus voltage failure. Inverter also implements soft-start, soft-brake and intellectual speed-adjusting during frequent start/stop and high/low load changing.
<- - I have an Opinion - ->