This paper presents the dispatch of reactive power compensation and real power curtailment of photovoltaic (PV) systems to prevent the overvoltage violation when load transfer between distribution ...feeders is executed. The voltage sensitivity factors of reactive power injection at all PV buses are derived according to the configuration of the distribution network. The advanced distribution automation system issues the control command to each PV inverter for adjustment of PV power generation, according to the sensitivity coefficients and PV installation capacity, so that the ancillary service of voltage support can be provided by all PV systems in a fairer manner. The practical Taiwan Power Company (Taipower) distribution feeders are selected for computer simulation, to verify the effectiveness of the proposed control method to mitigate the voltage violation problem for the operation of load transfer between distribution feeders with high penetration of PV installation.
Multi-agent systems (MAS) are emerging as a promising approach for smart power system restoration. After a fault has been detected and isolated, the maximum out-of-service loads should be restored in ...a timely manner. This study aims to develop reliable restoration through autonomous, rapid, and stable communication. For this purpose, a multilevel consensus is suggested to coordinate MAS in a fully decentralized fashion. System dynamics emerge in a distributed manner based on the state vectors of the agent and its proximate neighbors. The information matrix (IM) is used by the agents to accumulate and exchange state vectors encompassing common variable interests. In order to weight the influence of agents on voting, an optimized weighting model (Optw) is proposed. The parameters are bound by Lyapunov's assessment to ensure consensus and then optimized for quick convergence. The proposed multilevel topology supports parallel information discovery in local bunches and provides extremely quick convergence. The suggested one-by-one communication architecture facilitates the exchange of information since each agent only interacts with four of its neighbors. The redundant communication prevents a single point of failure. These achievements make it suitable for application in large-scale power systems. The effectiveness of the affirmation method is revealed through numerical simulation in various scenarios.
•Decentralized restoration by MAS using multilevel consensus.•Optw model, one-by-one topology, and multilevel consensus to accelerate convergence.•Parallel communication in local bunches of multilevel to expedite negotiation.•Globally stable MAS communication.•Global solution by providing global data via multilevel consensus.
A new solution method is introduced to the problem of optimally deploying manual and automatic switches in distribution systems, where the product of two continuous variables and the inverse of a ...continuous variable are reformulated as a linear relation. This leads to a (mixed integer linear problem) MILP power flow formulation too. The objective function includes cost and reliability. The cost term itself includes capital investment, installation, and maintenance costs (MC) as well as customer interruption cost (CIC); while the reliability term is represented by system average interruption duration index (SAIDI). The problem is formulated as a MILP, which guarantees a global optimal solution. The effectiveness of the proposed method is validated through various case studies and sensitivity analyses on the RBTS4, followed by a comprehensive discussion and analysis of results. The proposed MILP formulation prescribes fewer switches while achieving lower SAIDI, compared to that of a previous MINLP formulation.
A fault section in Korean distribution networks is generally determined as a section between a switch with a fault indicator (FI) and a switch without an FI. However, the existing method cannot be ...applied to distribution networks with distributed generations (DGs) due to false FIs that are generated by fault currents flowing from the load side of a fault location. To identify the false FIs and make the existing method applicable, this paper proposes a method to determine the fault section by utilizing an artificial neural network (ANN) model for validating FIs, which is difficult to determine using mathematical equations. The proposed ANN model is built by training the relationship between the measured A, B, C, and N phase fault currents acquired by numerous simulations on a sample distribution system, and guarantees 100% FI validations for the test data. The proposed method can accurately distinguish genuine and false Fis by utilizing the ability of the ANN model, thereby enabling the conventional FI-based method to be applied to DG-connected distribution networks without any changes to the equipment and communication infrastructure. To verify the performance of the proposed method, various case studies considering real fault conditions are conducted under a Korean distribution network using MATLAB.
Distribution automation systems in terms of automatic and remote-controlled sectionalizing switches allows distribution utilities to implement flexible control of distribution networks, which is a ...successful strategy to enhance efficiency, reliability, and quality of service. The sectionalizing switches play a significant role in an automated distribution network, hence optimizing the allocation of switches can improve the quality of supply and reliability indices. This paper presents a mixed-integer nonlinear programming aiming to model the optimal placement of manual and automatic sectionalizing switches and protective devices in distribution networks. A value-based reliability optimization formulation is derived from the proposed model to take into consideration customer interruption cost and related costs of sectionalizing switches and protective devices. A probability distribution cost model is developed based on a cascade correlation neural network to have a more accurate reliability assessment. To ensure the effectiveness of the proposed formulation both technical and economic constraints are considered. Furthermore, introducing distributed generation into distribution networks is also considered subject to the island operation of DG units. The performance of the proposed approach is assessed and illustrated by studying on the bus 4 of the RBTS standard test system. The simulation results verify the capability and accuracy of the proposed approach.
Due to the large amount of resources needed for implementing distribution automation systems (DASs), distribution companies (DISCOs) should develop long term plans for this project. Similarly, DISCOs ...have network capacity expansion (NCX) plans which specify the scheme of constructing the feeders and substations. Since considering DAS may lead to more efficient NCX plans, the planner should revise the NCX plan through the DAS planning. On the other hand, for DAS planning it is necessary to consider a NCX plan as a platform to determine the time and location for installation of automation equipment. Therefore the planner should simultaneously work on two plans, each of them affects the other. To facilitate this complicated planning procedure, this paper presents a novel method for integrated planning for NCX and DAS implementation. The proposed method develops a comprehensive plan in which the optimal scheme and schedule for constructing the lines and substations and installation of automation equipment is specified. To reduce the huge computational burden, an optimization method based on genetic algorithm is proposed. The proposed method is evaluated on an illustrative test network and the obtained results are presented and discussed.
Implementing automation system in distribution networks needs a huge investment that usually cannot be funded entirely in a short period of time. So distribution companies (DISCOs) should develop ...long-term plans to equip their network with automation technologies as far as economically justifiable. Aiming to provide a methodology for development such plans, this paper presents a novel multistage planning model for implementing distribution automation system considering all main hardware and software infrastructures. The proposed method optimally determines the type, location, and time in which an equipment or infrastructure must be added to network considering the network capacity expansion plan. The objective function of the planning problem is to maximize the net present value of the DISCO's profit in the planning time horizon. In this method, the optimization problem is solved using the genetic algorithm approach as a promising technique in solving the mixed integer nonlinear programming problems. The proposed method is evaluated on an illustrative test network and the obtained results are presented and discussed.
This paper introduces a multi-objective fault indicator (FI) placement method in electric distribution systems. The prevalent FI placement problem formulation is extended by considering effects of ...existing protection and control devices on customers' restoration time. Moreover, the customers' average restoration time index (CARTI) is proposed, as a new technical objective function with respect to uncertainties of automatic switching. Furthermore, a multi-objective solution approach is developed to simultaneously minimize indispensable economic and technical objectives. The resultant optimization problem is solved through a multi-objective particle swarm optimization (MOPSO) based algorithm, accompanied by a fuzzy decision making method to select the best result among the obtained Pareto optimal set of solutions. Assuming SAIDI and CARTI as technical objectives, the proposed method is applied to bus number four of the Roy Billinton test system (RBTS4), as well as a real-life distribution network with about 5500 customers, followed by a discussion on results.
State Grid Corporation of China and China Southern Power Grid Corporation put forward the vision of Smart Grid in 2009. Then China launched the second round of distribution automation system (DAS) ...project. This paper summarizes the DAS in this round, including the project planning, current development and related technical standard. The development situation and trend of feeder automation (FA) technology are focused. The various realization modes and test verification technology of FA are presented in details. With the integration of distributed generation to distribution grid, the trend of Advanced Distribution Automation (ADA) and other techniques such as optimizing operation and practicability of FA in China are introduced.
A distribution automation system is the integration of physical power distribution systems and information systems. Its information system guarantees the safe operation and reliable power supply of ...physical systems by monitoring, collecting and transmitting information. In the information system, the remote terminal unit of distribution automation is the hub of the information system, connecting it to the physical power system. Considering the unreliability of terminal information transmission in the information system, this paper aims to build a model to quantitatively evaluate the impact of unreliable transmission information on the power supply reliability of distribution systems. Firstly, the m-segment and n-connection unit model of distribution feeders is established, and then, the power supply reliability indices in the process of handling feeder terminal unit error are analyzed and calculated under the configuration modes of “three-remote” and “two-remote” of remote terminals. Then, considering the impact of a transmission error in the information system, the reliability index calibration model under the condition of unreliable information transmission is established. Finally, a case study is presented to illustrate how the proposed model is implemented.
