This article proposes a cooperative energy market model for an active Distribution Network (DN) by using the theory of Generalized Nash Bargaining (GNB). The proposed energy market has three types of ...participants: the DN operator, buyers, and sellers. Two energy trading manners are allowed at the same time: 1) each of buyers/sellers trades energy with the DN operator; 2) buyers and sellers trade energy in a Peer-to-Peer (P2P) manner and pay network usage fees to the DN operator. In the market, the DN operator actively manages voltage and reactive power (Volt-VAR) via controlling on-load tap changers of transformers and shunt capacitors. The payments among participants are subject to price constraints. The GNB problem for the proposed market is formulated and then decomposed into two subproblems: social welfare maximization problem (P1) and energy trading problem (P2). Both P1 and P2 are nonconvex problems. Next, linearization techniques are employed and a grid propagation algorithm is developed, transforming P1 and P2 into their equivalent Mixed-Integer Linear Programming (MILP) problems. In simulation, the proposed market model is compared with other GNB-based market models. The results show that the proposed one can significantly increase social welfare through Volt-VAR control and also can maximize the extent of fairness of profit allocation under the price constraints.
Power distribution networks (PDNs) has played a crucial role in expediting transition towards cleaner and better distributed energy sources. Nowadays, more and more distributed generations (DGs) are ...used in PDNs which complicates the automatic fault location. This article presents an accurate impedance-based method to determine the fault location for smart PDN in the presence of DGs. In addition, phase domain equations of distributed line parameters are used to enhance the accuracy of fault location. Two types of networks are considered. The first type of network is assumed to be fully observable with <inline-formula> <tex-math notation="LaTeX">\mu PMU </tex-math></inline-formula> and in the second type there are only a few <inline-formula> <tex-math notation="LaTeX">\mu PMU\text{s} </tex-math></inline-formula> with data loggers on the rest nodes. Load impedances of all nodes are estimated using pre-fault recorded information by present <inline-formula> <tex-math notation="LaTeX">\mu PMU\text{s} </tex-math></inline-formula> and data loggers. The proposed algorithm might suggest several points as possible fault locations for a PDN. To find out the actual location of fault same fault type is simulated for all suggested points. A matching value which is mathematically defined in the article, is calculated using recorded and simulated voltage to determine the actual fault point among all the suggested candidates. The accuracy of suggested method is analyzed against various conditions.
The rapid development of renewable distributed generation in active distribution networks (ADNs) imposes an increasing burden on the transfer capability of the ADNs, bringing new challenges to the ...distribution network expansion planning (DNEP) problem. Dynamic thermal rating (DTR), which evaluates the equipment rating based on the actual weather conditions and equipment thermal states, can enhance the equipment transfer capability to support the integration of renewable distributed generation. In this paper, we propose a DNEP model of ADNs incorporating the DTR of cables and transformers, given that underground cable feeder is preferred in the rapid urbanization trends. Then, we derive a linear reformulation of the original DNEP model and propose a modified Benders decomposition (MBD) algorithm to solve the DNEP model. To select more effective representative day scenarios, we propose a cost-based clustering method for representative day selection applicable to solving the DNEP model. Case studies based on the IEEE 33-node system and the PG&E 69-node system show that the implementation of DTR saves 14.7% and 15.1% of the investment costs of the two systems respectively. The effectiveness of the MBD algorithm and the cost-based clustering method is also verified by the case studies.
With the advantage of high-power supply capacity, low loss in power transmission and distribution process, strong power flow control ability, direct current (DC) distribution network has been one ...hotspot of the future distribution network. The cascaded multiport power electronic transformer (PET) has been proposed as key equipment for future distribution grid with multi-voltage level and alternating current (AC)/DC hybrid feature. Based on the typical topological structure and engineering reliability theory, a reliability evaluation model for PET considering the device redundancy is established. After that, the reliability evaluation method of the AC/DC hybrid distribution network with a cascaded multiport PET is proposed. Finally, case studies are provided in a ‘hand in hand’ AC/DC hybrid power distribution network structure. Case 1 analyses the PET reliability level under different design patterns and the redundancy level. Case 2 gives the reliability evaluation results of the AC/DC hybrid distribution network with PETs, which proves the correctness and validity of the proposed algorithm. Case 3 compares the reliability level of the AC and DC system under different scenarios and proposes the reliability promotion advice for the DC power distribution network.
Active power curtailment of residential PV systems is an effective way to mitigate technical issues in distribution networks. However, existing curtailment schemes can treat households unfairly; ...e.g., Volt-Watt schemes increasingly being adopted worldwide inherently penalize PV systems at remote locations in radial feeders. Nonetheless, whether fairness is improved or not by alternative curtailment schemes depends on how the impacts on households are considered. In this context, household-centric metrics that quantify PV harvesting, energy export and financial benefit are used along with the Jain's fairness index to assess fairness from different perspectives. To explore the trade-offs brought by schemes that consider fairness differently, four linearized, three-phase Optimal Power Flow (OPF)-based schemes are proposed to determine, periodically, short-term curtailment settings. Using a real Australian 22kV feeder and realistically modelled LV networks with 4,500+ households, a detailed comparison is carried out considering also a Volt-Watt scheme. Results demonstrate tha tall the schemes that consider fairness are effective in removing locational penalizations. However, in terms of fairness, their performance across the adopted metrics reveals noticeable trade-offs. This highlights the need for decision-makers to determine the metric from which fairness can be based upon in a way that aligns with their respective policies.
This paper elucidates a new real time energy management framework for radial active unbalance distribution networks (UDNs) by integrating load shedding and conservation voltage reduction (CVR) ...techniques. In contrast with the shortsighted real time optimization strategies, the proposed technique accounts offline beneficial aspects in real time optimization platform as time coupled stochastic expressions. Those are further simplified to a mixed integer non-convex programming (MINCP) using merger of Queueing theory and Lyapunov optimization process. To solve the complex MINCP portfolio, a consecutive mixed integer linear programming (c-MILP) based solution method is proposed after adopting necessary linear approximations. After demonstrating on modified IEEE 123 bus test network, it is showed that the proposed real time strategy can provide most energy efficient, secure and reliable operation to the UDNs and can accommodate offline advantageous attributes successfully along with the real time load shedding and CVR constraints. Validating the power flow solutions at OpenDSS platform, it is proved that the proposed c-MILP approach possess fast convergence and provide near optimal power flow solutions. Further investigations certify that presence of residential consumers are more beneficial for the networks as they are more sensitive to voltage.
Renewable energy resources (RERs) such as wind and solar are said to be considerable promising of the power system worldwide, and Afghanistan is evaluated for abundant and feasible electricity ...generation capacity from these resources. It fortifies merging of RER to the electric power system of Afghanistan where power quality issue sums up with scheduled and unscheduled load shedding due to the shortage of electricity. This research study presents an optimal solution comprising of rooftop solar photovoltaic (PV) as distributed generation to a real and substantial 162-bus electric distribution network (EDN) in Kabul, the capital of Afghanistan. Genetic algorithm (GA) based on Newton–Raphson power flow with the objective of power loss minimisation is put forward for sizing and placement of the solar PV at practically available locations or candidate buses of the network. This approach tends to reduce the dependency on the import power and at the same time improves the performance of the current system through minimisation of the total power loss and voltage deviation. The proposed method is simulated by MATLAB® software to compare and demonstrate the performance of the system under different scenarios of the PV allocations.
The accurate location of cable line faults is crucial in the troubleshooting of distribution networks. This paper introduces a cable fault location method based on the Decomposition of Time Reversal ...Operator (DORT) to address the challenges associated with cable fault identification in distribution networks. The proposed method utilizes the scattering matrix of the network and its eigenvectors to formulate a time reversal operator, effectively eliminating the impact of network topology and terminal reflections. Time-reversal (TR) waveforms are injected from each port of the network, and the time-domain response and spatial energy spectrum of each network segment are combined to pinpoint the fault location. Furthermore, this method is extended to multi-fault localization through the decomposition of differential scattering matrix, allowing for the identification of multiple faults using a single measurement of the fault scattering matrix. This extension significantly enhances the efficiency of fault location. Additionally, the effects of blind spots and Gaussian pulses on fault localization are analyzed. The results demonstrate the method's effectiveness in overcoming the influence of network topology and accurately locating various faults. Even in scenarios involving multiple faults, the proposed method can accurately locate all faults, which offer a promising solution for cable fault location in distribution networks.
The postdisaster restoration capabilities for critical loads in distribution networks need to be enhanced. In recent years, electric buses (EBs) have been widely used with the carbon-neutral target, ...which can be dispatched and discharged for load restoration considering their mobility and the V2G technology. However, the restoration capabilities of EBs are limited by the transportation system while the ac distribution network can hardly achieve power transfer between lines due to the radial constraint. In this article, a coordinated restoration method of hybrid ac-dc distribution network with EBs is proposed, which has flexible power transfer capability. The control modes of voltage source converters (VSCs) during the postdisaster period as well as the EB restoration capability considering transportation system constraints are analyzed in detail. Then, a bilevel programming model is developed to optimize the network reconfiguration, VSC outputs, and the proposed EBs dispatching scheme simultaneously, in order to achieve a better power transfer capability for load restoration considering their coordination. Simulation studies are performed to verify the proposed method.
Due to the lack of data in active distribution networks, employing new accurate measurement devices like phasor measurement units (PMUs) and micro-PMUs with a high reporting rate becomes an ...inevitable choice for the future vision of distribution systems. As a result, different algorithms have been presented to optimally place PMUs cost-effectively based on the estimation errors of the distribution state estimation (DSE) results. However, any component failure in measurement devices or communication links between sending ends and monitoring system of the distribution management system can significantly affect the DSE results. In response, this study introduces the reliability of satisfying accuracy constraints (RSACs) as an important requirement in the DSE problem. This reliability index along with the estimation errors of the DSE results are then used as two performance indices for determining the optimal number and location (configuration) of PMUs. Finally, the performance of the proposed algorithm in comparison with traditional approaches in different topologies and operating conditions of two considered ADNs is evaluated. The results proved that employing the RSACs in the optimal PMU placement problems leads to a PMU configuration with the optimum RSACs and also the cost and latency of the communication system between all configurations which have the same measurement cost and satisfy accuracy constraints of DSE results.
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