The increase in the trend of distributed generation has led to the formation of community microgrids. What is the best possible solution to connect single-phase loads to a microgrid with 2 level voltage source converter?
I feel one possible solution to connect single-phase loads is to use a 3-phase 4 -wire transformer.
You can use the split DC link which includes two series capacitor in parallel with a large balancing resistor for each of them . This a simple way to provide a neutral point which its voltage clamped at half of the DC link voltage .
Special PWM generating schemes can be used for balancing of the capacitors voltages. But where the neutral current is large, it flows through the capacitors and, hence, bulky capacitors are needed to make the voltage ripple on the capacitors. Also the neutral point usually drifts and becomes unbalanced when it includes DC component. So different strategies for neutral point balancing are reported, usually using the Space Vector Pulse Width Modulation or MPC control.
A better way to provide a neutral line is to add an additional fourth leg, called a neutral leg, to the conventional three-leg converter. The neutral current can be controlled to flow through the inductor so that the neutral point is maintained at the mid-point of the DC link. This allows the phase legs and the neutral leg to be controlled independently, which means the three phases can be controlled independently as well.
Ref :
Control of Power Inverters in Renewable Energy and Smart Grid Integration https://ieeexplore.ieee.org/book/6381785
Considering distribution systems in India, you will need a 3 phase-4 wire system, but for North American Systems, the distribution transformer is split phase. If you need more information on this, read my papers on Residential Microgrids:
Article A Benchmark Distribution System for Investigation of Residen...
Article Intra- and Inter-Phase Power Management and Control of a Res...
Conference Paper Cooperative Control and Power Management for Islanded Reside...
You can use the split DC link which includes two series capacitor in parallel with a large balancing resistor for each of them . This a simple way to provide a neutral point which its voltage clamped at half of the DC link voltage .
Special PWM generating schemes can be used for balancing of the capacitors voltages. But where the neutral current is large, it flows through the capacitors and, hence, bulky capacitors are needed to make the voltage ripple on the capacitors. Also the neutral point usually drifts and becomes unbalanced when it includes DC component. So different strategies for neutral point balancing are reported, usually using the Space Vector Pulse Width Modulation or MPC control.
A better way to provide a neutral line is to add an additional fourth leg, called a neutral leg, to the conventional three-leg converter. The neutral current can be controlled to flow through the inductor so that the neutral point is maintained at the mid-point of the DC link. This allows the phase legs and the neutral leg to be controlled independently, which means the three phases can be controlled independently as well.
Ref :
Control of Power Inverters in Renewable Energy and Smart Grid Integration https://ieeexplore.ieee.org/book/6381785
Dr Seyed Hossein Hosseinian ,
Thanks for the reply. I think the strategies you have mentioned are clear. Hope to implement it in my work.
Dr Syed A. Raza ,
Thanks for the reply. I will go through the papers recommended by you.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Energy
- Energy-Generating Resources
- Renewable Energy