Intelligent Load Shedding Using TCP/IP for Smart Grids


Computerized power management system with fast and optimal communication network overcomes all major discrepancies of undue or inadequate load relief that were present in old conventional systems. This paper presents the basic perception and methodology of modern and true intelligent load shedding scheme in micro grids topology by employing TCP/IP protocol for fast and intelligent switching. The network understudy performs load management and power distribution intelligently in a unified network. Generated power is efficiently distributed among local loads through fast communication system of server in the form of source and clients in the form of loads through TCP/IP. The efficient use of information between server and clients enables to astutely control the load shedding in a power system of micro grids system. The processing time of above stated system comes out to be 10 ms faster than others which ensure very less delay as compared to conventional methods. The Micro Grids system operating through TCP/IP control has been implemented in MATLAB/SIMULINK and results have been verified.

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M. Raza, M. Ali, N. Tareen, W. Rehman, A. Khan and A. Asar, "Intelligent Load Shedding Using TCP/IP for Smart Grids," Energy and Power Engineering, Vol. 4 No. 6, 2012, pp. 398-403. doi: 10.4236/epe.2012.46053.

1. Introduction and Background

In power system terminology, when some interdisturbances are leading the overall system towards instability, the final unwanted solution is load shedding. During load shedding some loads from interconnected network are disconnected for fast and quick recovery of an overall system to its initial settling state. Every grid station has its separate control that controls only the loads in terms of source management. For good management the power generation must be greater than the power consumption then system remains stable. Problems will occur if generation is unable to meet the demands of loads. Then small grids stations are not able to provide energy to their consumers and the only solution is load shedding, to remove power supply from the loads for the system stability.

Disturbances of any nature like hurricanes, faults, transients etc leads a system towards a fatal scenario and these unwanted actions may take place either on generation side, load side or transmission side depending upon the case. Damir proposed artificial neural network approach for intelligent detection [1,2] in power systems for stable operation on transmission lines and some issues were also discussed in a report [3] of NERC. Some methods were also suggested for transmission lines control [4] operation. Schemes of load shedding that has been adopted in past have been discussed in power system literature [5-8]. In breaker interlock scheme, when mains breaker was sending an emergency signal to connected loads breakers all loads were shed without any sequence or priority. However, high priority loads are left untouched during any disturbance and low priority loads are shed from supply. In second method called as under frequency relay scheme that was blind for detecting disturbances but reacted to changes. Slow response time of frequency relays and false dropping out of loads without check were its major discrepancies. Later on, PLCs System was introduced in an interconnected network but was lacking intelligence due to its blindness to transient shifts and slow response time for breakers to trip in emergency condition. Also, more loads were shed than required. Methods of checking voltage instability and actual loss of transmission capacity [9,10] have not been found.

The need for local load shedding [11] was proposed by Adibi for an over loaded equipment under certain time constraints. Conventional schemes were replaced by “Intelligent Load Shedding” [1] scheme which not only has fast response time by introducing TCP/IP for data transfer but manages dropping of specific loads based upon priority and accurately predicts shifts in available generation.

The paper under study has been divided into four main sections illustrating out the work in detail. The first section discusses ILS design using Transmission Control Protocol (TCP/IP), a link that provides intelligent network relation to fast data transfer while the second section relates a LV system (MG) with intelligent control and third section explains the implemented network in MATLAB/Simulink. Finally results are discussed and conclusions with future work have been presented.

2. ILS Design Using TCP/IP

In power system each connected network plays an important role either on supply side or generation side or load side .If one connected device becomes problematic than overall system goes towards instability. This is the very important and key feature in power system operation and control because the control and stability are related to each other uncontrolled system is basically unstable. And if that uncontrollable scenario in a power system is not tackled by quick shutdown than heavy blackouts and big disaster may occur in a system. This scene should be avoided because it really affects economic conditions of the organizations that are responsible for its functioning. Here reliability plays a very notable role in a sense that reliable systems are effective and unreliable systems are not stable for very long time. For good and efficient system stability should persists for an unlimited period of time until and unless operating conditions varies drastically. Quick and controlled actions are needed in any system to uproot the changes in controlling parameters which otherwise destroys the systems performance. Otherwise faults occur in a huge amount and connected equipment becomes faulty. It is the scenario where intelligent networks plays important role as traffic control and data transfer is very vital since jamming of information signals will prove fatal.

In Figure 1, block diagram shows the step by step events that will take place in a system quickly. Each block represents an event that has been taking place in a system. First of all power will be produced that will be constant and supplied to the central controller which will make a quick action and send information in form of bits to the local controllers that connected to the respective clients using computational engine. After receiving the useful information by local controllers it has been sent to clients for switching load breakers for an intelligent load shedding. Here all the information has been exchanged through TCP/IP platform because TCP/IP controls transmission, demand, distribution, load management and power in Power systems in sensible way and has much more recommendations proposed by Holland [12] for shifting electrical networks from SCADA to it. As numbers of system may be interconnected and they might sent data and information to each other so the system should be strong to hold such a heavy traffic and should be manage from not to get mal functional. As controller handles large amount of data and update it rapidly after mille second so it not easy for it to make decisions of each control and emergency signal at that specific time intervals. And delay can make Power system gets unstable. Therefore for the data transferring reliable medium should be used, having large band width and speed. Channel response should be fast too. For this to be accomplished transmission control protocol is prior for interconnected power system which not only provides high band width but also much quick in response. Secondly, it is connection oriented protocol and data traffic remains secure and safe.

Figure 2 shows that, server client—client model and information that has been transmitted on TCP platform. Server is the central controller having a data base and clients are basically loads here. Local Ethernet networking has been extended there. Communication between both parties is really fast and controlled intelligently by server.

Conflicts of Interest

The authors declare no conflicts of interest.


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