Distribution Generation is a better one from technical, economic and environmental concerns point of view. Its maximum capacity of up to 10mw makes the system simple to design, construct and operate. The DG usually uses renewable resources and is environmental friendly unlike the centralized power system (High capacity Power Transit). The economical and social benefits are undeniable as the power is being produced near the load. All the DGs can be connected through micro-grid and the micro grid can be connected to the central grid for reliability purpose. 

Dear Samuel,

That’s not the way I see it.

At first glance, it seems that DG is much better than HVDC however, the transmission network of a country can be connected to the grids of its neighboring countries using HVDC technology and as a result, such interconnected systems can provide so many technical and economic benefits for each country at a macro level.

Furthermore, the private investments on DG installation seem a time-consuming and lengthy process.

What is your idea?

Dear Morteza, concerning the technical issue, the challenge waits in the HVDC case as it needs precise controlling and handling of the system. Concerning the initial cost, this system needs a huge investment which can't be afforded by needy countries otherwise it could be cheap energy supply (lesser cost of energy/kwh of load). The time of investment is also an 'it depends issue' on the countries policy towards such investment. The interconnected system for HVDC can be there and is a good thing but doesn't mean the DGs are not important as they are the crucial part of the national grid if they are handled properly (grid connected). The DGs connected to the grid are will give any extra power they have to the grid which greatly increase the efficiency of the DGs and vise versa, the DGs take power for every pick power they experience during the day time and this increases its power security. 

Hi,

The technical benefits of DG units, especially for transmission-level grid, highly depend on the different operational characteristics of the plethora of types of DG units. Thus, some of them may be proved invalid. For example, the operation of stochastic units such as small-scale wind power plants and PV units may lead to an opposite effect regarding the necessary transmission capacity. 

It is not far-fetched that CHP systems (as controllable DG units) may have a positive effect while the presence of wind power plants (as non-dispatchable DG units) may instead lead to increased investment needs in power transport capacity, although such DGs are perceived as environmentally friendly units (renewable energy sources).

On the other hand, current technical recommendations like G83/1, G59/1, IEEE 1547 and CEI 11-20 prescribe that DGs should be automatically disconnected from the MV and LV distribution networks in case of tripping of the circuit breaker that supplies the feeder connected to the DG. Therefore, with greater DG penetration, automatic disconnection of DGs for loss of grid situation drastically reduces the expected benefit of DGs. It also leads to unnecessary loss of DG power in the event of utility fault and increases the complexity of protection system.

With the above-mentioned reasons, I think we have to think about other alternatives for power supply such as interconnection with neighboring countries through HVDC.

How do you think about it?

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Morteza

http://mortezash.blogfa.com/

In my opinion, Import power supply through HVDC is totally difference from supply within zonal by DG. HVDC is classified as one of a transmission method, another is AC transmission. Of course, electricity from sending end can be transfered whatever surplus primary resources are. On the other hand, DG is classified on a generation system. Its characteristics are distributed according to their primary resources. Additionally, some of them are intermittent resources e.g., wind and solar. These are zonal power generation with high potential in some area and some are cost free. For a rich area of these renewable energy, converting to electric energy into grid is beneficial. Technical problems following is not trivial however it later on. In conclusion, either Supply through HVDC or DG have their own character so that cannot make a decision that which one is better. Thus, planning of bringing generation into zone must be considered from area to area or country to country.

Dear Komson,

I agree with your idea mentioned in the last sentence ' it must be considered from area to area or country to country'. However, I believe that we can compare the benefits of DGs and HVDC systems because both of them provide valuable economic benefits for generation section of the power system as a whole, the former locally (or nationally) and the latter externally (or internationally).

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Any contribution and participation in this discussion would be highly appreciated.

I feel that we are forgetting the fundamentals of DG. The concept of DG is to basically exploit the locally available sources, which are renewable in majority. The concept of HVDC links between countries will further boost the centralised generation, which is conventional sources based in majority. I feel This concept is contradictory to emission reduction and clean energy.