Nancal 10.5kV 280-800kW Medium Voltage converter used in Power plant

Application field: Waste Incineration Power Plant
Products: Nancal Medium Voltage AC drives
Capacity: 280kW-800kW
Load: Primary fan, Induced draft fan, Pumps
Functions: Processing control; Soft start; energy saving

In recent years, due to the impact of rising energy prices, it has become an urgent problem for waste incineration power plants to reduce the cost and power consumption.
With the development of the medium voltage AC drives technology, it is available to choose drives to adjust the speed of fans and pumps, and achieve the energy saving and consumption reduction in power plant.
This article is mainly introduce the application of Nancal 10.5kV AC drives used in Zhejiang waste incineration power plant.
Introduction of Project:
The project is an expansion project with a daily domestic waste disposal capacity of 600 tons, equipped with a 600t/d mechanical grate incinerator and a 15MW steam turbine generator set.
Fans and pumps are the main energy consumption devices of power plant, and the consumption accounts for 65%-75% of the electricity consumption of the plant.
The traditional solution is to adjust the air volume by adjusting the intake damper, which has serious energy loss. Some power plants use hydraulic couplers for speed regulation, but the energy-saving effect is not very significant, the current use of variable frequency speed regulation technology is the best choice to improve the operating efficiency under low load. The following table shows the performance comparison of using hydraulic coupler and frequency converter:



Hydraulic coupler

Drive method

Smooth speed regulation, wide range

Hydraulic drive, narrow range


VFD+ motor +load

Motor+ hydraulic coupler +load




Speed accuracy


High start acceleration

Soft start character

No fluctuation to grid

Fluctuate to grid

Start current

Low start current

Direct start, high current

Maintenance/Spare parts

Easy maintenance; few spare parts, easy to obtain

Large maintenance workload; whole machine for spare parts

Fault diagnosis



Power factor

High, have reactive power compensation function

Low, need extra compensation device






Shanghai Nancal provides a complete solution including 4sets of Medium Voltage VFDs for induced draft fan, primary fan and circulating water pump, as shown in the following table:


Nancal VFD model




NC HVVF-10.5/10.5-800


Induction draft fan


NC HVVF-10.5/10.5-280


Primary fan


NC HVVF-10.5/10.5-400


Circulating water pump


The above four sets of AC drives adopt the manual bypass system, that is, when the converter is faulty or overhauled, the load can be driven by the grid directly without stop, it can ensure the continuous production.

The system diagram of single set is as follows:



The main functions that can be achieved by this solution:

  1. Meet the operational requirements of on-site fans and pumps.
  2. Soft start the motor, avoid the impact on the grid and prolong the service life of the motor
  3. Realize energy saving and reduce consumption, provide working efficiency of fans and pumps. Reduce operating cost.
  4. Bypass solution can realize the continuous running during the VFD maintenance and failure.



The main features of Nancal HVVF series AC drives:

  1. Voltage source, multi-level PMW technology
  2. High performance vector control
  3. 2.3-18kV output, without any step-up transformer
  4. Low harmonic, meet IEEE519-1992 standard
  5. Low du/dt
  6. SIL2 & CE certifications