Branch Current Decomposition Method for Loss Allocation in Radial Distribution Systems With Distributed Generation

Abstract

The allocation of the system losses to suppliers and consumers is a challenging issue for the restructured electricity business. Meaningful loss allocation techniques have to be adopted to set up appropriate economic penalties or rewards. The allocation factors should depend on size, location, and time evolution of the resources connected to the system. In the presence of distributed generation, the variety of the power flows in distribution systems calls for adopting mechanisms able to discriminate among the contributions that increase or reduce the total losses. Some loss allocation techniques already developed in the literature have shown consistent behavior. However, their application requires computing a set of additional quantities with respect to those provided by the distribution system power flow solved with the backward/forward sweep approach. This paper presents a new circuit-based loss allocation technique, based on the decomposition of the branch currents, specifically developed for radial distribution systems with distributed generation. The proposed technique is simple and effective and is only based on the information provided by the network data and by the power flow solution. Examples of application are shown to confirm its effectiveness.

Using smart meters to estimate low‐voltage losses

“…Hence the fair allocation of the costs resulting from these poorly known low voltage losses, is difficult. This is a particular issue when evaluating the benefits from embedded generation reducing current sizes around the network and hence the size of the losses [5], [6], [7], [8], or assessing the consequences of new load types such as electric vehicles [9].…”

“…Having customer smart meter readings available for a low voltage circuit will allow the "copper" losses to be estimated using a load flow analysis [6], [10]. Not only will this avoid the coarse approximations involved in using loss factors and allow a temporal breakdown of the losses, but the consequences of phase imbalance [9] and embedded generation can be accounted for.…”

Steady-State Assessment of the DG Impact on Voltage Control and Loss Allocation

“…Furthermore, in distribution systems local loads or generators are owned and managed by different entities, and operated within specific regulatory frameworks. In order to allocate the distribution system losses, the DNO is considered as the subject undertaking bilateral contracts for loss allocation with the distribution system entities (Carpaneto et al, 2006a). The distribution system losses are allocated to the local generators and loads connected to the distribution system nodes, excluding the slack node.…”

“…As a consequence of the conceptual differences indicated above, it is possible to apply the loss allocation methods formulated for transmission systems to the distribution systems, provided that the losses allocated to the slack node are redistributed among the other nodes (Carpaneto et al, 2006a). A simple way to avoid allocating losses to the slack node is to connect the slack node to the reference node with a null impedance, that is, to impose the slack voltage magnitude to zero in the network used for determining the loss allocation; in this case, it is possible to use the loss allocation methods defined for transmission systems for allocating losses in distribution systems, as shown in the examples presented in Carpaneto et al, 2006b.…”

“…These techniques can generally be partitioned into derivative-based and circuit-based. The correctness in the formulation of the computational techniques depends on avoiding the occurrence of the loss allocation paradox identified in Carpaneto et al, 2006a.…”