In a grid tied solar PV system i heard like what ever power solar module is producing is getting injected to the grid assuming grid is an infinite source and sink. So for the grid injection we have to synchronize the voltage generated by the PV.My doubt us during the synchronization process any loss of power transfer will occur?
For example in a particular instant the module is producing 2KW. Will these whole 2 kw gets injected to the grid?
OR during the synchronization process some losses will occur?
Helps will be deeply appreciated.
PV modules are connected via the grid via an inverter. The inverter does the MPPT tracking, converts DC to AC, transforms to the right voltage and takes care the inverter output is in phase with the grid. A modern inverter will have an efficiency of over 95% .
PV modules are connected via the grid via an inverter. The inverter does the MPPT tracking, converts DC to AC, transforms to the right voltage and takes care the inverter output is in phase with the grid. A modern inverter will have an efficiency of over 95% .
Losses are inevitable in a system. We can reduce these losses by using advanced converter(DC-DC,DC-AC) topologies.Some topologies will make the system unstable,this will badly affect the overall performance of the grid.
Dear Vinu,
can you expound how a topology may lead to instability?
Isn't it a matter of properly controlling the flow of energy and not how the hardware is arranged?
I think inverter's PLL synchronizes with grid reference in less than a second, perhaps even within ms range. Synchronization has no economic impact on your feed-in.
There is risk of instability with some control principles: the simple control of voltage proportional to current results in a negative resistor in parallel to the grid, which might oscillate on a high impedance at high frequency, or in parallel with similar converters. The second problem is that processor controls contain a delay in the current control and tend to destabilise the current control at high frequency. A way to investigate it is that equivalent impedance of the converter should be damping at all other frequencies than the grid, which corresponds to a positive real impedance. One can also test step responses. This has to do with stability, but is a special convertor type:
"Using numerical inverse laplace for optimizing the current control in grid coupled inverters" https://biblio.ugent.be/publication/5801279
This is rather an overview:
"New design trends in photovoltaic converters" https://biblio.ugent.be/publication/4187878
Without galvanic seperation, the efficiency is some 2-3% lower than without.
Indeed the PLL or other synchronizing techniques does not influence too much. A PLL is integrating from frequency to phase. If the loop integrator adds a 90° phase delay it is unstable, so the right phase lead has to be given. Also the reaction of the PLL on harmonics might still influence the stability. If the PLL is uses zero crossing, and not fundamental based, harmonics or spikes can influence the zero crossing.
Dear Ajan,
See the following manuscripts too. They provides a helpful practical sight for DG connections (such as PV) to the main grid in micro grid studies.
Regards,
Morteza Shabanzadeh
http://mortezash.blogfa.com/
Data Voltage Source Inverter (VSI) Simulation and Design using MA...
Data Current Controlled Voltage Source Inverter (CCVSI) Simulatio...
Data Simulation and Design of Distributed Generation Units' Conne...
I think Vinu Sankar ·Jethro Betcke 's explanation is good enough.
THe system power loss includes dc gathering loss ,ac loss and converting loss which caused by inverters.
And for different type of plants,such as centralized plants, residential system or distribution system , the loss varies in a wide range.
- Badges
- Science topic