PQ HUB
Shanghai Residential Area
Static Var Generator
The Industry
Static Var Generator is based on the voltage-type inverter principle, and uses the insulated gate bipolar transistor (IGBT) to control the size and phase of the inverter AC voltage, so as to achieve the purpose of reactive power and harmonic compensation.Since the switching frequency of IGBT is very high (up to tens of kHz), So the SVG can quickly compensate for the reactive load, At the same time, a very high compensation accuracy can be achieved, The SVG is currently the best solution in the field of reactive power control.
Background
The residential area power grid belongs to the low-voltage distribution network, which is generally connected to the large power grid by 10/0.4kV transformer. The load in the network is mostly working in the three-phase 480V and single-phase 220V voltage levels, mainly for some small capacity loads, such as air conditioning, refrigerator, TV and other household appliances.Most household appliances are non-linear loads and produce a lot of reactive power during use.
Power Quality Problem
Reactive power is too large, its adverse effects are also very prominent, the increase of reactive power will lead to the increase of the system current and apparent power, resulting in the capacity of the generator, transformer and other electrical equipment and wire increase.The increase of reactive power will increase the total current, thus increasing the loss of the equipment and the line, and increasing the voltage drop of the line and the transformer.
Solution
Mixed reactive power compensation is widely used in residential distribution networks. The compensation capacity is generally configured according to 30% of the transformer capacity, and the SVG capacity and capacitor capacity are generally configured according to user needs.The transformer capacity of a residential distribution station in Shanghai has 800kVA, and a 240kvar Static Var Generator device is equipped on site.
Performance
Reactive power and PF before compensation
Reactive power and PF after compensation