Power Analysis Of Different Distribution Systems

Distribution Systems


Characteristic Features:

  • Micro grid¬†consists of two parts:
  • Solid State Circuit Breakers
  • Micro-power supplies (distributed generations)
  • Sub-station transformer
  • Seven interconnected buses (bus1 is generator bus; buses 5,6,7 are load buses)
  • Three PMT‚Äôs
  • Three breakers

Reason behind the selection of SLD:

Due to rapid growth of electricity demand, grid expansion and several world-wide blackouts, the vulnerability of large power grids is fully exposed. Therefore the world has now trying to move towards a new power technology-Distributed Generation i-e DG through micro-grids. Distributed power generation has outstanding features.


  • flexible power generation
  • Environmental compatibility
  • Better controllability of power system operation
  • Better meet with the power quality
  • Increased reliabilty of consumers


 Micro grid can be installed in limited area and its results can be studied. Thus its feasible to implement this on a limited scale first then move towards larger scale.

Cost Analysis:

Additional investment is required in this innovative technique.

Cost to benefit ratio must be calculated before installation.


 Fig.2   Sld of a general power system to study different power system parameters

Characteristic Features:

¬∑         3-sync.generators                   9-bus system                         6 lines

¬∑         3 loads                                    3- two winding t/f

Reasons behind the selection of SLD:

This SLD enables the power engineer to have a deep eye on the following aspects:-

¬∑         Analyze the dynamic performance of interconnected power systems.

¬∑         Examines the characteristics of the various components of a power system during normal operating conditions and during disturbances.

¬∑          Explores the detailed mathematical models of system components and analyzes the system behavior using the necessary computational tools.


¬∑         Power engineers when finds out the above information then they are well able to model and operate the system under the most economical, reliable and in an appropriate manner.

¬∑         Besides consumers are also directly benefitted.


¬∑         This SLD is vey simple and easy to implement for the different areas of engineering study.

Cost Analysis:

¬∑         Capital required for it is zero percent. It just requires the determination and will power from the Power Engineers side.


Fig.3  Sld shows a small distribution system

Characteristic Features:

¬∑         Above sld depicts a small distribution system. The electric company distributes power at 69kV, which in turn feeds a 13.8kV distribution system by a 13.8kV, 3-phase, 50-Hz, 20 MVA distribution transformer with an impedance of 8.5%. The 1,000kVA, 6.7% impedance transformer is used to step the voltage down from 13.8kV to 480V.

¬∑         Here the point of study is the understanding of harmonics generation and harmonic voltage arises due to it.

¬∑         Keep in mind that PCC stands for ‚ÄúPoint of common coupling‚ÄĚ. It is the electrical connecting point or interface between the utility distribution system and the customer’s or user’s electrical distribution system.

Reasons behind the selection of SLD:

¬∑         To improve the ‚Äúpower quality‚ÄĚ is the most in and current  topic of discussion among all the distribution Engineers of the world .

¬∑         Until and unless the position of harmonics at each and every component of power system is not known by the engineers then how could they improve the quality of power? Therefore the above sld is short listed.


It equipped the Distribution Engineers with the following flow advantages:-

¬∑         Finds the current harmonics at each and every load in the system.

¬∑         Compare the obtained results with the IEEE Standards ratings.

¬∑         Harmonics are filter at each individual load and measured easily at the point PCC.


¬∑         Feasibility is 100%

Cost Analysis:

¬∑         Its most economical due to PCC since no need to measure the harmonic distortion at each and every point which ultimately saves the capital


Characteristic Features:

¬†The load is grouped at bus 7 and consists of an impedance modeled as a RL load (120MW/32Mvar) supplied by a single generator (250MVA/13.8 kV) and a bulk power system modeled as an infinite bus (10GVA/230kV) by a two transmission lines. The generator is powered by a multi-stage steam turbine which is connected to the network through a¬†Y¬†‚ÄstD¬†step-up transformer (350 MVA, 13.8/230 kV).¬†The STATCOM/SMES i-e static synchronous compensator and superconducting magnetic energy storage system is placed at main bus (bus 4) with the purpose of participating in the primary frequency control of the electric system together with the generator, in case when severe disturbances are occurred.

Reasons behind selection of this sld:

The SLD is selected since it depicts one of the fundamental concepts of power engineering that is ‚Äúprimary frequency control mechanism.‚ÄĚA professional Engineer should, infact must know about the controlling of frequency and its different methods.


  • The knowledge of frequency, variation in frequency and its control ultimately made the Power Engineers to safe the precious equipments and power system from massive damage.
  • In the meantime consumers also benefitted directly.
  • Security and reliability of power system is enhanced.


  • STATCOM /SMES is a new research.
  • Requires experienced and technically sound persons to be implemented.
  • Sincere and serious efforts required to be implemented in Pakistan.

Cost Analysis:

  • ¬†Firstly the results can be judged by installing STATCOM/SMES at certain locations.
  • If desired results are achieved then can be implemented on large scale.
  • Cost of energy storage devices is not too high so its economically feasible.


 Fig.5  Sld depicts protection of equipment through grounding resistor

Characteristic Features:

  • Neutral¬†Grounding¬†Resistors¬†are¬†used¬†to¬†protect¬†power¬†transformers,¬†power¬†generators¬†and¬†otherassociated¬†equipment¬†in¬†your¬†power¬†systems¬†against¬†50/60¬†Hz¬†faults¬†(short¬†circuit)¬†and¬†transient¬†phenomena¬†(lightning).
  • Rated¬†current:¬†from¬†1¬†amp¬†to¬†2000¬†A
  • Rated¬†voltage:¬†from¬†0.4¬†to¬†35kV
  • Rated¬†Resistance:¬†from¬†1¬†ohm¬†to¬†2000¬†ohm
  • Rated¬†time:¬†1¬†sec¬†to¬†continuous¬†time¬†rating
  • All¬†Neutral¬†Grounding¬†Resistors¬†are¬†designed,¬†rated,¬†manufactured¬†and¬†tested¬†in¬†strict
  • with¬†IEEE32.¬†Routine¬†tests¬†performed¬†on¬†each¬†Neutral¬†Grounding¬†Resistor¬†are¬†measurement¬†of¬†resistance,¬†high¬†voltage¬†power¬†frequency,¬†insulation¬†measurement
  • Standard¬†unit¬†includes¬†the¬†stainless¬†steel¬†resistor¬†assembly¬†plus¬†all¬†the¬†required¬†

insulators, internal connections and hardware installed in a standard safety enclosure. NeutralGrounding Resistor units are completely assembled, prewired, and tested at our facility

Reasons behind the selection of this sld:

  • Protection is a technique where the world engineers move to and a lot of work is still in progress for the security of the power system. That‚Äôs why the SLD has a right to be short listed here.
  • Protection is a backbone in power system. Due to this immense significance this sld is selected.
  • SLD shows in a very simple manner that how can be a transformer or any equipment can be operated safely.


  • Little amount of initial investment protects the most precious machines.
  • Consumers are benefitted directly once again.


  • The SLD shown above is much feasible in its nature.
  • Feasibility of this can be better judged by experienced engineers at particular location of particular site either they have to use this or not.

Cost Analysis:

  • Costing PKR=100,000 -10,00,000/-.
  • Professionally and technically its wise to invest this amount in order to safe the most precious. equipments costing millions of rupees.
  • One time initial investment saves the power system.
  • Hence security and reliability increased.

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