Variateur de fréquence moyenne tension dans pompe de condenseur de machine de 600MW
2010-1-4 10:43:19
Résumé : cette page introduit les caractéristiques opératoires et principales du variateur de fréquence VFD, ainsi que l’analyse et la comparaison des effets d’économie en énergie via des tests.
Mots clés : variateur de fréquence moyenne tension MV VFD, pompe de condenseur, ajustement de vitesse à fréquence variable, économie en énergie.

Luanhe Power Plant locates in Chengde city of Hebei province. 2 sets of 100MW turbine generators started to run in 1993 and 1997. The plant reformed with Leader Harvest VFD on condenser pumps in March, 2005. VFD has been running stably. Its energy saving is obvious.

I. Work state of condenser pump

After being cooled and condensed in condenser, steam is collected in hot-well. Condenser pump transfers condensing water to deaerator in time. Keeping pump stability and safety is key to ensure whole plant safety. So monitoring and adjusting water level in condenser is important.

In normal operation, water level can not be too low or too high. When load increases, condensing water increases, water level goes up. When load is low, water level is down.

Power of motors is 6kV/1000kW with redundancy. One motor works and the other is spare. Before reforming with VFD, water level is controlled by adjusting outlet valve opening. Adjusting quality is bad and great energy is wasted on valve. Frequent adjustments cause valve reliability down.

After reforming with VFD, outlet valve opens fully. Outlet flow is controlled by adjusting motor speed.

II. Principal of HARSVERT-A06/130 VFD

HARSVERT-A series VFD adopts technology of multi-level PWM topology. Several LV PWM power cells series connect to output medium voltage. Optical fiber connects MV circuit and controller.

These are advantages of VFD: soft start, soft brake, auto speed adjusting, small start current, continuous adjustable start-up time. Leader Harvest VFD has self-copyright operation&monitor software. Local /remote start/stop, function, parameter, fault, record are shown in WINDOWS interface of colourful LED touch screen. The interface can show voltage/current waveform, frequency and speed at any time. Integrated fault monitor circuit and precise fault orentation detect each part of VFD. All power cells are intellectually designed. When there is fault, the fault information is sent back to main controller. Controller closes IGBT in time to protect main circuit. Fault position, type are shown on HMI. This makes fault point clear at a glance and it is applicable for common personnel.

When external analogue signal is broken or short circuit, VFD supplys alarm signal and keeps output frequency same. Control power source of VFD accepts AC220V and DC 220V. UPS is equipped in VFD to ensure continuous operation if control power is broken.

III. Precaution

To prevent air from entering condenser and avoid breaking vacuum, pressure of condenser main pipe can not be too low. When deaerator pressure is more than pressure of main pipe, steam and water of deaerator inside come back to condenser, which causes water impact in main pipe. Thus outlet valve can not open fully in variable frequency state.

IV. Energy saving effect

We made comparison test for 1# condenser pump on 17 May, 2005. VFD saved energy 470kW, 611kW, 631kW in state of 100MW, 75MW, 50MW. Energy saving rate was 47.4%, 70.8%, 78.4%. The details is in following table: