Frequency Converter with active grid control
and several 100 sets in wind-power operation.
The special features of
- Adjustable control algorithms are integrated for detection and to compensate harmonic distortion and in combination with ride through capability during grid-disturbance.
- In the converter cabinet, the circuit breakers for the mains connection as well as the 400 V distribution for the internal WT power-supply are integrated.
- Control equipment for communication inside the wind-turbine.
- Control-strategy to protect the generator winding from high voltage spikes.
- Monitoring of grid stability and no WT shutdown, in case of disturbances in the power grid within adjustable limits.
- Control equipment for communication inside turbine.
- High efficient liquid cooling to dissipate IGBT losses based on converter perience since 1995.
ACTIVE GRID FILTER
Harmonic and Reactive Current Cancellation with PQF
Application for Single-phase and 3 Phase. From 100kVA up to 3MVA.
In contrast to traditional capacitor circuits, the reactive compensation by active-control is operating continuously without transients and switching distortions, and the fast reaction guarantees high quality of power.
The compensation can be either capacitive or inductive according to the reactive and harmonic current control of reduced power factor and low efficiency.
In order to eliminate these problems, a parallelly operating inverter-system can be used to shape the current to a sinusoidal waveform and to increase power factor.
The principle of active grid control is based on measuring the harmonic currents and compensating them by current injection in the opposite phase. The compensating current is created by PWM of a two- or three- phase IGBT inverter and a DC capacitor bus. The inverter is connected to the grid by coils and a small filter circuit.requirements of the application
Example of a three phase active compensator
The graphs show a three phase grid connected to a non-linear load. The harmonic and reactive currents of the load are compensated.