Utilization of information from remote-controlled elements for the MV distribution system control

The explosive growth of the Internet demands higher reliability and performance than what the current networking infrastructure can provide. This dissertation explores novel architectures and protocols that provide a methodology for grouping together multiple networking elements, such as routers, gateways, and switches, to create a more reliable and performant distributed networking system. Clustering of networking elements is a novel concept that requires the invention of distributed computing protocols that facilitate efficient and robust support of networking protocols. We introduce the Raincore protocol architecture that achieves these goals by bridging the fields of computer networks and distributed systems. In designing Raincore, we paid special attention to the unique requirements from the networking environment. First, networking clusters need to scale up the networking throughput in addition to the scaling up of computing power. Second, task switching between the different services supported by a networking element has a major negative impact on performance. Third, fast fail-over time is critical for maintaining network connections in the event of failures. We discuss in depth the design of Raincore Group Communication Manager that addresses the forgoing requirements and provides group membership management and reliable multicast transport. It is based on a novel token-ring protocol. We prove that this protocol is formally correct, namely, it satisfies the set of formal specifications that defines the Group Membership problem. The creation of Raincore has already made a substantial impact both at Caltech and the academic community as well as in the industry. The first application is SNOW, a scalable web server cluster that is part of RAIN, a collaborative project between Caltech and JPL/NASA. The second application is RainWall, a commercial solution created by Rainfinity, a Caltech spin-off company, that provides the first fault-tolerant and scalable firewall cluster. These applications exhibit the fast fail-over response, low overhead, and near-linear scalability of the Raincore protocols. In addition, we studied fault-tolerant networking architectures. In particular, we considered efficient constructions of extra-stage fault-tolerant Multistage Interconnection Networks. Multistage Interconnection Networks provide a way to construct a larger switching network using smaller switching elements. We discovered an optimal family of constructions, in the sense that it requires the least number of extra components to tolerate multiple switching element failures. We prove that this is the only family of constructions that has this optimal fault-tolerance property.

Local nonspiking interneurons in the thoracic ganglia of insects are important premotor elements in posture control and locomotion. It was investigated whether these interneurons are involved in the central neuronal circuits generating the oscillatory motor output of the leg muscle system during rhythmic motor activity. Intracellular recordings from premotor nonspiking interneurons were made in the isolated and completely deafferented mesothoracic ganglion of the stick insect in preparations exhibiting rhythmic motor activity induced by the muscarinic agonist pilocarpine. All interneurons investigated provided synaptic drive to one or more motoneuron pools supplying the three proximal leg joints, that is, the thoraco-coxal joint, the coxa-trochanteral joint and the femur-tibia joint. During rhythmicity in 83% (n = 67) of the recorded interneurons, three different kinds of synaptic oscillations in membrane potential were observed: (1) Oscillations were closely correlated with the activity of motoneuron pools affected; (2) membrane potential oscillations reflected only certain aspects of motoneuronal rhythmicity; and (3) membrane potential oscillations were correlated mainly with the occurrence of spontaneous recurrent patterns (SRP) of activity in the motoneuron pools. In individual interneurons membrane potential oscillations were associated with phase-dependent changes in the neuron's membrane conductance. Artificial changes in the interneurons' membrane potential strongly influenced motor activity. Injecting current pulses into individual interneurons caused a reset of rhythmicity in motoneurons. Furthermore, current injection into interneurons influenced shape and probability of occurrence for SRPs. Among others, identified nonspiking interneurons that are involved in posture control of leg joints were found to exhibit the above properties. From these results, the following conclusions on the role of nonspiking interneurons in the generation of rhythmic motor activity, and thus potentially also during locomotion, emerge: (1) During rhythmic motor activity most nonspiking interneurons receive strong synaptic drive from central rhythm-generating networks; and (2) individual nonspiking interneurons some of which underlie sensory-motor pathways in posture control, are elements of central neuronal networks that generate alternating activity in antagonistic leg motoneuron pools.

Within the carbon constrained world, virtually unrestricted integration of renewable energy sources into power networks is expected to become common in practice, making power systems to be more ubiquitous[1] in nature, structurally and operationally. Consequently, handling the intermittent and random behavior of renewable generation, thus Load Frequency Control (LFC), would become one of the major challenges in power systems operations in the future. In this paper we report a simple method that can support LFC of Ubiquitous Power Networks, rich in renewable generation. In the proposed method, frequency control support is achieved through the coordinated control of active power produced and consumed by various controllable system elements at distribution level where renewable generation is expected to appear in large scale. Simulation results obtained for a test system are also presented to demonstrate the effectiveness of proposed method.

GRID technology, emerging in the late nineties, has evolved from a metacomputing architecture towards a pervasive computation and information utility. However, the architectural developments echo strongly the computational origins and information systems engineering aspects have received scant attention. The development within the GRID community of the W3C-inspired OGSA indicates a willingness to move in a direction more suited to the wider end user requirements. In particular the OGSA/DAI initiative provides a web-services level interface to databases. In contrast to this stream of development, early architectural ideas for a more general GRIDs environment articulated in UK in 1999 have recently been more widely accepted, modified, evolved and enhanced by a group of experts working under the auspices of the new EC DGINFSO F2 (GRIDs) Unit. The resulting report on ‘Next Generation GRIDs’ was published in June 2003 and is released by the EC as an adjunct to the FP6 Call for Proposals Documentation. The report proposes the need for a wealth of research in all aspects of information systems engineering, within which the topics of advanced distributed parallel multimedia heterogeneous database systems with greater representativity and expressivity have some prominence. Topics such as metadata, security, trust, persistence, performance, scalability are all included. This represents a huge opportunity for the database community, particularly in Europe.

Advancing high impedance fault localization via adaptive transient process calibration and multiscale correlation analysis in active distribution networks

To date utilities have focused predominantly on the quality of treated water and the physical condition of distribution assets when improving the quality of water at the customer's tap. However, the quality of the water delivered is also affected by the time the water is retained in the different elements of the distribution network. As water passes through a distribution system, its quality, with respect to many chemical and biological parameters, will degrade as a result of chemical processes and biological reactions that occur in the bulk water and at the pipe wall. Pipe wall reactions are strongly influenced by the distribution system materials and the contact time of the water with them. AwwaRF published the findings of the research project, titled #2796: Managing Distribution Retention Time to Improve Water Quality in May 2006 as an electronic guidance manual. The software based decision support tool provides a structured approach and practical methodologies for managing water quality by controlling retention time. The presentation will introduce the session "Meeting Current and Future Drinking Water Standards: The Role of Retention Time Management" setting the background to the session using incidents and projects to illustrate some of the issues surrounding deteriorating water quality in distribution systems and how they could be managed efficiently. The presentation will conclude with an introduction to the electronic guidance manual developed during the research project. This paper therefore provides the background to the presentation. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF).

Distributed generators (DGs) are nowadays most commonly used in distribution networks to meet the rising demand. The distribution network power flow is altered as more distributed generations are integrated with the distribution network. Analyzing and researching the network's power flow with distributed generation is an essential element of analyzing the distributed generation's influence on the networks. This study proposed new sites in the test network for the purpose of connecting DGs. Good results were obtained in improving the necessary network elements. Firstly, applying a Newton-Raphson method to measure the distribution network's power flow without distributed generations. Then the optimal power flow approach with DGs is set up based on many goals such as minimizing fuel cost, minimizing losses, voltage deviation, increasing efficiency, and the incremental fuel cost in the network appeared. Eventually, applying Particle Swarm to overcome the optimization problems. In MATLAB software environment and programing MATPOWER version 6.0, the simulation is evaluated and validated using the IEEE30 node method. The test results indicate that optimal power flow analysis with distributed generation will accomplish many networks aims and boost system economy.

The possibility of applying the measure of information uncertainty (entropy) in structural reliability analysis of electricity distribution networks is assessed. The essential factors influencing the process of reliability analysis and related to the presence of information uncertainty are highlighted. The peculiarities of reliability analysis in network designing and operation, when it is required to estimate the state of elements and choose the efficient structure of a network are considered. The opportunities and limitations in the application of existing methods of structural reliability analysis are evaluated; it proves the importance of information uncertainty measurement. The conceptual apparatus of entropy includes the mathematical procedure of its calculation. Fail-safe operation probability and probability of network element failure are taken as reliability index. The mathematical expressions proposed for calculating entropy are applicable when there are two independently functioning network elements, each of which will be able to be in one of two states with a fraction of probability: operable and non-operable. The obtained results allowed identifying the more reliable elements/objects. The application of the proposed mathematical procedure allows to compare network elements with each other through the value of entropy and to choose the most reliable ones. Thus, the proposed solution is a preliminary step in the uncertainty removal task.

Communication is very important to distribution automation (DA) because DA relies on the coordinated effort of various elements in the system. Many communication systems have been designed for DA so far. However, most of these communication systems use proprietary (vendor specific) protocols and are for individual instead of all DA functions. Thus, there has long been a great need for an open and integrated communication system capable of supporting all DA functions transparently. This paper presents a new communication infrastructure, PS-TCP/IP (power system TCP/IP), for all DA communications including customer services. PS-TCP/IP can support all DA functions transparently because it follows three design principles. First, each network element (NE) involved in DA communications, including customer meters, is assigned a unique network-layer address which corresponds to their relative position in the power distribution network. Second, all NEs can communicate with each other as long as they encapsulate their data in a standard-format "IP datagram". Third, any ISO layer 1 and 2 protocols can be incorporated easily. PS-TCP/IP's design follows ISO's layered approach. This means that the structure of the communication system is independent of that of any DA function's, thus creating a truly open and transparent communication environment for all DA functions.

With the development of the intelligent and interactive power system, the elements of distribution network planning continue to increase. The distribution network connects the transmission system and individuals, directly affects the individual’s power consumption experience, and is a key link in the power system. A reasonable planning scheme can not only improve the power supply capacity and reliability of the distribution network but also fully apply the data of each system in the distribution network to realize the optimal planning of the medium-voltage distribution network driven by data. Firstly, this paper constructs the CIM model and the distribution network topology model and establishes the wiring pattern recognition feature library. The network reconstruction and planning method research was carried out for the target line, and a typical operation scenario of the distribution network was generated. At the same time, based on the time period network loss index, the distribution network reconfiguration optimization model and distribution network expansion planning model are established, and the solution method of the distribution network reconstruction and expansion planning model is expounded. A reconstruction optimization scheme with the best overall network loss performance is in the network operation scenario. The experimental results of the final example show that based on the proposed time period network loss index, the overall operation loss of the distribution network in a period can be calculated more accurately, and the optimized planning scheme is more suitable for the load power consumption characteristics of the region, and the method has certain feasibility.

The aim of this thesis is to investigate novel recharging schemes for energy demand management (DM) of electric vehicles (EVs). While there has been a lot of work highlighting the importance of energy DM of EVs, most of the reported works do not expand on suggesting how such a DM system may be implemented. In this thesis the focus is on two aspects of DM system implementation. At the instantaneous control time scale, an alternative mechanism for frequency regulation with the aim of neutralising sudden changes in output power of electric generators is presented. At the recharge planning time scale, the aim is to avoid congestion and undesirable voltage drops in the distribution system, and a novel approach is presented that can improve voltage profiles. The problem of considering both voltage congestion and frequency regulation in a composite DM framework is also addressed. At the instantaneous control time scale, a novel distributed recharging rate controller is presented that is based on non-linear control and that yields a real time and distributed solution. This controller minimises communication overheads and allows EVs to join and leave at arbitrary times. From the perspective of recharging rate allocation, the controller achieves a Pareto efficient allocation which is also proportionally fair. The proposed controller is then applied to a system with a single, isolated, and unregulated synchronous machine and it is shown that the frequency can be used as proxy to the imbalance between produced and consumed electric power and hence communication overhead can be eliminated in such cases. A protocol is also discussed that can modify the controller and can implement the modified controller in a multi-machine system. Simulation is used to show the frequency regulation and fairness of recharging rates of EVs when the protocol and the modified controller are used. Subsequently, the integration of the recharging rate controller with the legacy protection system is also discussed. At the recharge planning time scale, the problem of congestion in the distribution system is addressed. Most of published literature on distribution system voltage issues deals with control of various network elements, for instance, on-load tap changers or banks of shunt capacitors on the distribution feeders. In this thesis, a complementary approach 7 8 is presented that can also improve voltage profile by scheduling EV load in such a manner that undesirable voltage drops are avoided or their severity is diminished. In this context, a novel approach is presented for recharging EVs in the same geographic neighbourhood that share the same secondary circuits when recharging. The approach is based on a numerical method called Smoothed Particle Hydrodynamics (SPH) that has been previously used by other researchers to solve the equations of fluid dynamics. The characteristics of the method used for the proposed approach as well as its performance in term of improvement in the reduction of voltage drops and its adaptation to elastic and non-elastic loads is highlighted via simulation. Finally, the approach is extended to also provide a frequency control reserve service.

This paper proposes a self-healing method for active and smart distribution systems. The method uses a distributed algorithm for Fault Location, Isolation, and Service Restoration (FLISR) to enhance the reliability of active distribution systems. The proposed FLISER method is designed to be implemented in the relays of the circuit breakers (CBs) of distribution lines. The same algorithm is executed for all the CBs and each CB only communicates with the adjacent CBs. Therefore, the proposed method takes advantages of the benefits of distributed methods. To provide a fast service restoration, especially when a zone of the distribution grid is disconnected from the upstream transmission system, the method uses a five-step process to provide the required power for loads of the faulted feeder by use of tie lines and the available capacity of distributed generators (DGs). In comparison with the previous works, in the proposed method the minimum number of CBs are opened. The exchanged data between the network elements can be transferred by use of the IEC61850 protocol and in the form of standard GOOSE messages.

This paper introduces the implementation and utilization of domain-specific information in a decision support system (DSS) for logistics distribution networks. This information is used to steer an evolutionary algorithm’s search for promising configurations of the network. Results show that utilizing this information improves the performance of the DSS.

Open knowledge platform can provide a purified knowledge base. Thus, we build a platform for several application areas in a cloud computing that supports APIs for various data based on a knowledge utilization model. The goal of this platform is to maximize the utilization of the knowledge base. In order to achieve this goal, we designed the structure of this platform as an open knowledge platform. The targets of the design are to maximize the utilization of data linkage, to expand it to national common knowledge and to increase its usability by providing services with knowledge graphs. In order to design the platform we identified users, information sources, and infrastructures. In the process, we found it is crucial to specify roles and services to the users of the platform. The requirements are induced from a utilization model and scenario of the service based on the knowledge graph. With the service scenario, stakeholders of the platform started narrow down function modules needed to support the service. One of the modules is a national common knowledge in the knowledge base, which provide essential connected knowledge to support solving regional problems of government such as earthquake, flooding. To increase the usability of data scattered by departments and agencies, data linkage, and knowledge between fragmented data sets is included in this platform. Subsequently, we designed modules to support the effective utilization of this knowledge information. Also, we found that a cloud infrastructure instead of in-house hardware and software could provide flexible and compatible services for the platform. Moreover, the cloud system has advantages on big data analysis and distributed system interconnection. Utilization model and scenario-based process modeling provide a systematic approach to design an open knowledge platform that supports many required components enabling interoperability, compatibility, and connectivity among other knowledge bases..

The paper presents an efficient and overall analytical approach towards the prognosis of reliability indices in the process of development of medium voltage city distribution networks. The presented model gives possibility for estimation of duration of the interruption of supply of the load points in question, due to unexpected failure at some, arbitrarily chosen, element of radial distributive network. Repair crew movement during searching for the faulted cable section is modeled, in order to estimate time needed for isolation and renewal of supply of load points. The differences in strategies of searching and isolating of the faulted section are also taken into consideration. The reliability analysis is possible in the case that the dispatcher and the crew for maintenance search for the section by use of halving method or by the method of measuring the resistance of isolation using megaommeter. Application of the model and developed computer program is illustrated on the example of the real network of the city of Novi Sad. Some feeders are analyzed as unstationary elements which during the planned period change the configuration, number of load points, load and unit outage costs. The change of configuration is manifested by connection of new MV/LV substations between the existing ones, or by prolongation of lines. The change of the configuration of open loop depending on link arrangement is considered. The results give a real reliability picture of the present but also of the future MV network. In addition, data thus obtained can be used as basic ones for the estimation of benefits in cost-benefit analyses.