Reactive Power Loss Allocation Research Articles

A novel index for identification of weak nodes for reactive compensation to improve voltage stability

In this study, a new reactive power loss index (RPLI) is proposed for identification of weak buses in the system. This index is further used for determining the optimal locations for placement of reactive compensation devices in the power system for additional voltage support. The new index is computed from the reactive power support and loss allocation algorithm using Y-bus method for the system under intact condition and as well as critical/severe network contingencies cases. Fuzzy logic approach is used to select the important and critical/severe line contingencies from the contingency list. The inherent characteristics of the reactive power in system operation is properly addressed while determining the reactive power loss allocation to load buses. The proposed index is tested on sample 10-bus equivalent system and 72-bus practical equivalent system of Indian southern region power grid. The validation of the weak buses identification from the proposed index with that from other existing methods in the literature is carried out to demonstrate the effectiveness of the proposed index. Simulation results show that the identification of weak buses in the system from the new RPLI is completely non-iterative, thus requires minimal computational efforts as compared with other existing methods in the literature.

Real and reactive power loss allocation in pool-based electricity markets

Although real power is the main traded commodity in electricity markets, reactive power plays crucial roles in power systems reliability and security. Market participants utilize the network differently to maximize their profits. It means that their effects on the system, such as losses, can also be different. The development of a fair and accurate loss allocation scheme for real and reactive power is significant to avoid cross subsidies and to have the correct charge for each participant. This paper introduces a new method to allocate real and reactive losses in pool-based markets. The basic idea assumes that network users have their own effects on the system as well as their interactive effects which are based on their contributions to currents flows. The proposed method determines these contributions and adjusts them, due to system nonlinearity, according to Current Adjustment Factors (CAFs). Unlike other approaches, the proposed method can easily and effectively allocate real and reactive losses simultaneously without any additional calculation except the substitution of line reactance instead of resistance. The proposed method is illustrated on a simple system and tested on the standard IEEE-14-bus and IEEE-30-bus systems. Results have shown validity and consistency of the proposed method.

Towards reactive power markets. Part 2: Differentiated market reactive power requirements

Two major contributions are discussed in this part of a two-part set. first, it presents a new concept of market reactive power requirement (qreq) for every participant in both bilateral and pool markets. this qreq is defined as the reactive power loss allocation to each bilateral transaction using current adjustment factor (CAF) method that has been proposed in part 1. when a transaction is allowed to provide reactive power more than its qreq, it contributes to system reactive power needs and it is considered a reactive power provider. on the other hand, if it cannot produce its qreq, it relies on other reactive power sources to ship its contracted power and it is considered a reactive power consumer even though it may generate some reactive power. the concept then is extended to participants in a pool market. secondly, this paper proposes a new general concept of differentiated reactive power requirements for every participant in electricity markets. it assumes that qreq of a participant depends on its allocated losses using any appropriate loss allocation method. the proposals help system operators and market participants to trade reactive power as well as real power effectively and fairly. the simulation results show validity and consistency of the proposals.