Dear Bishal

In my opinion the others are

1. Totat harmonic distrortion (THDu %) which is limited by national and international norme at the begining of the feeder which supply LV line with PVs

2.  Protection coordination of upsteram protection devices since PVs contribute to fault currents at LV feeder, not much, but if you have high penetration of PV it can be a problem,

Srete

Dear Bishal

Synchronization with the grid frequency, voltage level and wave form (sinusoidal) is handled by the inverter. There are different allowable standards for voltage limit. frequency and harmonic level based on distribution voltage level.

At LV distribution systems, large scale penetration of PV contributes most in THD as explained in 1st answer. In Canada, the government is limiting the use of PV as the PV farms operating in most cities have reached the short circuit capacity of the network. 

Dear Sir(s),

Thank You for your wonderful insight in my query.

However, i still feel an urge to mention. I understand, The concern regarding the THD in the system is particularly due to the Power Electronics based fast switching Inverters which could still be mitigated using proper active filter or any other way, applicable (Please correct me if I am wrong).

What i am still concerned about is a bit broader aspect. I mean, considering mediating parts like inverters are made to operate in low THD, what are other abnormality that the LV power distribution system has to face? Shouldn't we be concerned about the fact that PV are non inertial sources? and similar other concerns that might have cascading effect in the HV upstreams?

Regards,

Bishal

1) The problem of transient stability only arises when you have multiple synchronous generators in your distribution system.

2) I think Steady state voltage violation, Reverse power flow, Harmonics and Islanding are the prime problems with PV based distribution.

Howdy Bishal, 

When installing your PV use a dc ac converter and you should have no problems on your side of the distribution. The voltage and frequency regulation is the network operators problem. This is valid for small generation up to a tens of kilowatts and being connected to a national network. 

For distributed generation and local networks outwith the national networks. The situation changes dramatically. The intermittent sources such as solar, which produce a high current source for prolonged periods during the day, should utilise battery storage to get the maximum benefit of the energy available. Good storage and dc ac converters coupled with system control should be able to sustain any small or mid sized network. Generally based on diesel generators with renewable penetration. 

The middle ground is generating power in the region of 150 to 600 MW and distributing power on both sides of the meter. A generator must have a grid card to supply power to the grid in this scale. The includes ancillary services which require system control and costs. 

In summary, your question depends on the scale and the type of distribution.

Cheers

Gav 

look up synchronization parameter with between grid and inverter. most of cases inverter voltage would be little bit of higher because of low quality of filter design since the goal is to push the power into the grid. before connecting the grid inverter should be equipped with sophisticated protection system with reliable logic because of any abnormalities would be tends to short circuit fault in your system. Ultimately you are not going to blow your system and it could be catastrophic in case of LV grid failure.      

PV solar generator connection should be analyzed for all typical parameters which are common in DG analysis, such as voltage variations, power loss, short circuit, bidirectional flow, protection, power quality, intermittence etc. When it comes to transient stability analysis, which has traditionally been reserved for transmission systems, PV solar generators in LV network are usually not scrutinized in this sense. The broader picture is mainly concerned with the increase in the popularity of microgrids and the capability of an LV network to operate in both standalone and grid connected mode. In this sense, transient stability and small signal analysis are becoming important and are required in order to ensure safe and effective operation of the microgrid. This is mainly because of an interaction of control systems of DGs, switching operations required for transition from standalone to grid connected mode (and vice versa) and low inertia inherent to small DG

Very interesting observation of Mirza Saric for the future of PVs and other DGs. Some crucial questions need to be solved how PVs and other DGs may operate in islanding mode (standalone mode) with the part of distribution network. Now it is in our country forbidden by National grid code.

From a DSO point of view the most relevant issues, when it comes to LV- and MV-connected PV, are voltage quality (slow voltage variations, fast voltage variations, total voltage drop, etc.), local congestion management, uncontrolled islanding. Voltage problems generally arise first than congestions; islanding problems strongly depend on regulating capabilities TSO may impose to small-size PV (P-f, Q-V, LVFRT, etc.). For a quick overview of problems and nonconventional solutions, you may see the outcomes of PV Grid EU-Funded Project (http://www.pvgrid.eu/home.html).

From a DSO point of view the most relevant issues, when it comes to LV- and MV-connected PV, are voltage quality (slow voltage variations, fast voltage variations, total voltage drop, etc.), local congestion management, uncontrolled islanding. Voltage problems generally arise first than congestions; islanding problems strongly depend on regulating capabilities TSO may impose to small-size PV (P-f, Q-V, LVFRT, etc.). For a quick overview of problems and nonconventional solutions, you may see the outcomes of PV Grid EU-Funded Project (http://www.pvgrid.eu/home.html).

Dear All,

Thank you very much for your valuable insight and response in my query. These are very helpful for me.

Regards,

Bishal

Protection coordination, then voltage rise, then harmonic pollution, then impact on reactive power compensators ... etc