Power Tracing in a Deregulated Power System : IEEE 14-Bus Case Satyavir Singh Indian Institute of Technology, Rookee,India E-mail: [email protected]Abstract In this present era , a fair transmission pricing scheme is an important issue due to incresed deregulation and restructuring of power sector. In this view, issue of tracing the flow of electricity has been gain importance as its solution helps in evaluating a fair and transparent tariff.An electricity tracing method would make it possible to charge the generators and/or consumers on the basis of actual transmission facility used. This paper focuses on tracing of electricity using Bialek’s tracing algorithm .Case study is carried out using an IEEE 14- bus system with three simultaneous bilateral transactions simulated in Power world simulator. 1. Introduction Power system operation in many electricity supply systems worldwide, has been experiencing dramatic changes due to the on going restructuring of the industry. The vertically integrated structure of power industry is being replaced by market structure which led to a significant increase in power wheeling transactions. In such a structure a transmission system is being used by multiple generation and load entities that do not own the transmission system. In view of market operation it becomes more important to know the role of individual generators and loads to transmission lines and power transfer between individual generators to loads. Basically there are three methods for power tracing which are described below [1]: 1.1. Node method In a meshed transmission network there are number of possible routes by which electrical power can flow from sources to sinks. It is possible to determine relation between the generators/loads and the flows in transmission lines by means of sensitivity analysis, that is by determining how a change in nodal generation/demand influences the flow in a particular line [2, 3]. Although this method based on dc load flow and sensitivity analysis cannot consider accurately, the reactive power transfer allocation and system non linearity. A novel electricity tracing method has been proposed [4] which, under the assumption that nodal inflows are shared proportionally between the nodal outflows, allows one to trace the flow of electricity in a meshed network. This method was proposed by J.Bialek [5] .The complete description of this method for the tracing of real power is given in section 2. The characteristics of nodal method are given below: (i) The transmission losses must be removed from the lines before the application of the method. (ii) Matrix calculation is more complex and the speed is a problem for a big network. (iii) The method can handle cyclic flows in the system, so the method is suitable for systems with loop flows. (iv) If MVAR tracing is required, the method becomes messy with the introduction of artificial nodes. In [6] a new method for determining the generator’s contribution to a particular load is presented. The method uses the nodal generation distribution factors (NGDF-s). It features a search algorithm, capable of handling the active and reactive powers. Paper [7] provides new insights into the electricity tracing methodology, by representing the inverted tracing upstream and downstream distribution matrices in the form of matrix power series and by applying linear algebra analysis. A rigorous mathematical proof of the invertibility of the tracing distribution matrices is given, along with a proof of convergence for the matrix power series 1.2. Graph method This method assumes that a generator has the priority to provide power to the load on the same bus and is based on the following lemmas of graph theory [8]. Lemma 1: A lossless, finite-nodes power system without loop flow has at least one pure source, i.e. a generator bus with all incident lines carrying outflows. Lemma 2: A lossless, finite-nodes power system without Satyavir Singh et al ,Int.J.Computer Technology & Applications,Vol 3 (3), 887-894 IJCTA | MAY-JUNE 2012 Available [email protected]887 ISSSN:2229-6093
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Power Tracing in a Deregulated Power System : IEEE 14-Bus Case
Table 7: Power flow results with generator and load data record
Conclusion
In a deregulated environment, generation, transmission
and distribution are independent activities. This
unbundling of the transmission services has resulted in
need to trace the flow of power i.e. to assess the impact of
a particular generator or the load on the power system.
This paper is based on Bialek’s tracing method which
may be applied to both real and reactive power flows.
The results corresponding to the upstream looking
algorithm tabulated in table 1 and 2 allows one to assess:
What amount of power from a generator goes to
a particular transmission line (Table 1).
What amount of power from a generator goes to
a particular load (Table 2).
The results corresponding to the downstream looking
algo tabulated in table 2 and 3 allows one to assess:
What amount of power from a generator goes to
a particular load (Table 2).
The contribution of a particular transmission line
flow to a particular load (Table 3).
References
[1] M. W. Mustafa and H. Shareef, “A Comparison of Electric
Power Tracing Methods Used in Deregulated Power Systems” First International Power and Energy Conference PECon 2006, Putrajaya, Malaysia, November 28-29, 2006, pp. 156-160
[2] Rudnick. H., Palma. R. and Fernandez. J. E., "Marginal
pricing and supplement cost allocation in transmission open
access', IEEE Trans., PWRS-10, (2), 1995, pp. 1125-1142.
[3] NG. W.Y., "Generalized generation distribution factors for
power system security evaluations", IEEE Trans., PAS-100, (3),
1981, pp.1001-1005.
[4] Bialek, J., “Identification of source-sink connections in
transmission networks”. Proceedings of fourth IEE conference
on Power system control and management, London, April 1996,
pp. 200-204.
[5] J. Bialek, "Tracing the flow of electricity," IEE Proc. Gener.