International Journal of Electrical, Electronics and Data Communication, ISSN: 2320-2084
Volume-1, Issue-10, Dec-2013
MINIMIZING DISTRIBUTION LOSSES BY SYSTEM RECONFIGURATION 1
MANJU MAM, 2SANDEEP SAINI, 3LEENA G, 4N.S. SAXENA 1,3
EEE, FET, MRIU, Faridabad, Haryana PG Student, Power System, Dept. of Elect. Engg., DCRUST, Murthal, Haryana 4 MDI, Gurgaon, Haryanan Email:
[email protected]
2
Abstract— The paper proposes a reconfiguration method for radial distribution systems. The effectiveness of the proposed method is demonstrated on a test system. The network is reconfigured for loss minimization and to relieve the overloading of the network components. This system reduces the computational burden. The application results show that the proposed method is efficient for the minimization of real power loss of radial distribution systems. CYME software simulation has been used for achieving this. Keywords—Distribution system, Radial network, Reconfiguration, Loss minimization
I.
Thus there are many techniques to reduce the power loss in the distribution system. Reconfiguration of the distribution system can achieve the following i) decrease the real power loss ii) Increase system Reliability iii) Exchange the voltage profile iv) Increase the Power factor
INTRODUCTION
Network reconfiguration is performed by opening sectionalizing (normally closed) and closing tie (normally open) switches. The switching operation is performed in such a way that the network remains radial and all the loads are energized. A normally open tie switch is closed to transfer a load from one feeder to another while an appropriate sectionalizing switch is opened to restore the radial structure. The configurations may be varied with manual or automatic switching operations so that, all the loads are supplied and reduce power loss. Reconfiguration also relieves the overloading of the network components. Network reconfiguration is a combination problem, and many techniques for reducing the real power loss in network reconfiguration system have been provided such as: Branch exchange method [2], tabu search technique [3], genetic algorithm [4], and ant colony method [5]. This paper shows that the minimizing the real power loss of a network distribution system results in improvement of voltage stability and load balancing of the system. A branch exchange method was used in which approximate formulae is provided to reduce losses due to feeder reconfiguration in [6,7]. In another technique by Shirmohammadi and Hong [8] the switches were opened one by one beginning from a fully meshed system, based on an optimal power flow pattern. Another algorithm by Goswami and Basu [9] is based on optimal flow pattern, of a single loop, formed by closing a normally open switch, and the switch with minimum current was opened. A method based on partitioning the distribution system into group of load buses, such that the line section losses between groups of nodes were minimized is given by Sarfi et al. [10]. But in [11,12], solution strategies have been proposed for feeder reconfiguration using simulated annealing. Borozan et.al [13] based on approaches in [7, 8] proposed a heuristic method for three-phase unbalanced systems.
II.
PROBLEM FORMULATION
Minimum Loss Model In a radial distribution system, the load section is also divided into each radial feeders with sectionalizing switches and is connected to other feeders via many tie switches. In the network reconfiguration problem the loss minimization can be expressed mathematically as follows:
Where n total no of branches r branch of resistance i ; q branch of reactive power i ; p branch of active power i ; v voltage on head node of branch i ; k switch on branch i ,1 can equal to closed, 0 can equal to open; A simple distribution system with two sub-stations[6] can be represented as:
In this system A1, A2, A3, A4 and B1, B2, B3, B4 are the nodes between the two feeders A and B. Where K is the tie switch which is placed in between
Minimizing Distribution Losses By System Reconfiguration 3
International Journal of Electrical, Electronics and Data Communication, ISSN: 2320-2084
the two nodes A4 and B4. S1, S2, S3, S4, S5, S6, S7, S8 are sectionalizing switches in this two feeders distribution system. The main method of branch exchange can be expressed as follows: to find the original flow and to get the power losses first, a loop is formed when a closed the tie switches, and then choosing a sectionalizing switch we open the loop to get back the radial topology. In Baran M.E. [7] and Zhang Dong [15], all the tie switches in the network are searched and calculated during reconfiguration process. In the proposed system, an 11 KV, 16 node bus system has been considered with base reconfiguration based on 1 MVA. The line data, bus data, and tie switches data are based on [1]. The 16 bus test system is shown in fig 2.
Volume-1, Issue-10, Dec-2013
During network reconfiguration by opening and closing 6 suitable switches i.e. (s21, s17, s18, s10, s19, s20) respectively, the voltage, reactive and apparent power profiles are shown.
Fig 5 Voltage profile of the test system
Fig 6 KVAR profile of the test system
Fig 2 A simple 16 bus test system
The aim of the study is to minimize the active loss. In this system some electrical conditions of line length, properties of cables, feeder etc. and so on are required. The bus and branch data for the 16 bus system is entered using the software. The real (active) power losses in optimal configuration is calculated at 10 MW which has been reduced to 5.93 MW. III.
Fig 7 KVA profile of the test system
B. After System Reconfiguration case The branches 3-8, 5-12, 6-13, 9-15, 10-16, 10-12 to 2-3, 8-9, 9-10, 11-12, 12-13, 10-12 are open now. When the switches s2, s8, s9, s15, s16, s20 are open, the losses calculated are 10MW as per [1]. By the proposed system the losses have been further brought down to 5.93 MW with the same switching position. The change in the switching position is shown in fig 8.
NETWORK MODEL IN THE SOFTWARE ENVIRONMENT
The network can be created to calculate power losses before and after reconfiguration. A distribution system network is created in software environment as shown in fig 3:
Fig 3 16 Bus System Fig 8 Switching Position (s2, s8, s9, s15, s16, s20) Open
A. Before system reconfiguration case Before system configuration, the real power loss is 14.2 MW when the switches s21, s17, s18, s10, s19, s20 are in open position.
By opening and closing 6 suitable switches i.e. (s2, s8, s9, s15, s16, s20) respectively, the voltage, reactive and apparent power profiles can be seen.
Fig 4 Switching Position (s21, s17, s18, s10, s19, s20) Open
Fig 9 Voltage profile of the test system
Minimizing Distribution Losses By System Reconfiguration 4
International Journal of Electrical, Electronics and Data Communication, ISSN: 2320-2084
Volume-1, Issue-10, Dec-2013
REFERENCES [1]
[2]
[3]
Fig 10 KVAR profile of the test system
[4]
[5] Fig 11 KVA profile of the test system [6]
TABLE 1 TABLE SHOWS THE TOTAL LOSSES IN KW [7]
[8]
TABLE 1 TABLE SHOWS THE TOTAL LOSSES IN KW
[9]
[10]
[11]
CONCLUSION In this paper, the system reconfiguration has been done using CYME software to minimize the losses and to keep the system balanced. This method simplifies the distribution network, keeping the constraints in view. Test results have been presented which shows that losses as proposed in earlier method can be further reduced.
[12]
[13]
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