New Publications are available for Control of electric power systems
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New Publications are available now online for this publication.
Please follow the links to view the publication.An adaptive, agent-based protection scheme for radial distribution networks based on IEC 61850 and IEC 61499
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0764
This paper shows a possible implementation for an auto configurable protection scheme based on the well-known logic selectivity concept, using an agent-based architecture with standard communication protocol (IEC 61850) and programming language (IEC 61499). An easy-to-use technique to integrate the two standards is shown, enabling the exploitation of encapsulation capabilities provided by IEC 61499 to provide easy to maintain and reusable code, along with interoperability with 61850-enabled IEDs. The proposed scheme can also implement automatic reconfiguration of protections following network topology changes. (4 pages)A methodology for the redesign of frequency control in modern power systems in presence of renewable energy resources
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0893
The Ministry of Energy in Iran published a target to install 5GW Renewable energy resources to be connected to grids by 2015. However, as outputs from wind power generation fluctuate time to time and wind power resources are available only in specific areas, deterioration of the quality of utility's power supply has become an important issue to be solved .this paper proposes a new algorithm to participate wind power generation in frequency control, with cooperation of DSO and TSO. For above purpose, this paper also introduce a new concept, Bulk Virtual Power Plant. (4 pages)Volt/Var control in a microgrid with consideration of uncertainty of generation in both grid-connected and islanded modes of operation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0799
In this paper, a strategy based on Genetic algorithm for optimal allocation of reactive power resources in distribution system with microgrid is presented. In the proposed approach uncertainty in power generation of renewable based DG is considered. The main objective is to allocate fixed and switched capacitors as reactive power resources for voltage control within the desired limits on a distribution system with microgrid in both grid connected and islanded modes of operation in single stage. Case study was carried out in a local distribution system with DGs to demonstrate the effectiveness of the proposed methodology. (4 pages)Coordinated voltage control in distribution systems under the smartgrid concept
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0858
The deployment of the smart grid concept requires more automation and control in electrical distribution systems in order to be able to accommodate Distributed Energy Resources (DER), particularly those based on Renewable Energy Sources (RES). This paper presents a hierarchical control architecture designed for electrical distribution system comprising two main control layers. This structure enables the implementation of advanced functionalities such as coordinated voltage control between the MV and LV levels, exploiting Distributed Generation (DG) capabilities together with traditional voltage control techniques. The performance of the proposed voltage control algorithm is illustrated based on simulation results using real distribution networks. (4 pages)Reactive power compensation of self-induced voltage variations
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0886
The significant increase in renewable energy resources in distribution networks has introduced novel technical challenges to distribution system design and operation. The integration of intermittent DGs, like solar and wind, into the distribution network poses a challenge to the traditional voltage regulation strategies due to the alteration of power flow patterns, and the variability of the DG output. It is now commonly accepted that a high level of renewables penetration into the distribution networks would ultimately require the participation of DGs in voltage regulation. To date, no ideal approach exists for how the DGs can best contribute to the voltage regulation. This paper presents a new reactive power regulation method for the compensation of self-induced voltage variations. The proposed approach achieves sufficiently accurate voltage compensation with very little to no communication requirements. A further significant advantage is that this approach does not violate the restrictions imposed by standards. (4 pages)Evaluation of reactive power control concepts for PV inverters in low-voltage grids
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0892
The proportion of renewable energies in power generation has increased significantly in recent years according to the political aims. In low-voltage grids, these are mostly distributed intermittent generation systems such as photovoltaic systems that are connected through inverters to the grid. Thus, the distribution networks have to meet hitherto unfamiliar technical challenges. A temporary reversal of the power flow can cause overvoltage problems. Traditional voltage regulation strategies cannot solve this problem. Consequently, regenerative sources need to be turned off temporarily or on the long term the grid infrastructure has to be extended by the network operator. Therefore, the distributed generation has to take part in the voltage regulation. With the help of reactive power, which is generated by the solar inverters, power capability and voltage quality of the networks can be increased. Thus, grid extension can be delayed or even avoided in many times. This paper presents a new approach to the evaluation of reactive power control strategies. Different reactive power control concepts are simulated and evaluated concerning their efficiency, effectiveness and stability. (4 pages)Increasing demand for voltage control in secondary substations
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0853
German grid operators are facing increasing challenges regarding voltage limits in grids with large numbers of installed PV systems. In order to allow for the development of advanced technical solutions to overcome these challenges and therefore to increase the capability to install PV in low voltage distribution grids, a model to assess the voltage level in grids with different levels of PV penetrations has been developed. Results show a strong need for voltage control in secondary substations and derive basic guidelines for application as well as development criteria. (4 pages)Voltage regulation (MV) by means of Q(U) - Simulation and measurement on a 12 MVA PV power plant
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0841
Open loop reactive power (Q) control function of the local voltage (U) measured at the inverter's terminals is one possibility to comply with the BDEW's MV grid regulations [1] in Germany, while other countries are considering to apply this solution as well. A better understanding of the stability limits for such a control algorithm is required when applying it to large PV plants or PV dominated grids. A dynamic RMS simulation model of a big PV plant including Q(U) control is developed. The model is compared with real life measurements in the PV plant and the local laboratory. Various study cases are further on performed in order to assess the voltage stability. An upper stability limit can be found depending on the grid connection parameters in the point of common coupling (PCC). (4 pages)A pseudo-real time distribution network simulator for analysis of coordinated ANM control strategies
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0849
This paper describes a pseudo-real time distribution network simulator developed to investigate the use of real time distribution system control presets to better integrate high levels of distributed energy resources into active distribution networks. A combination of historical and modelled generation profiles, along with varying demand patterns, are used to demonstrate the real time application and improved system response from active network management control strategies. (4 pages)Active voltage control - from theory to practice
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0809
Active voltage control has been studied extensively in the past decade but only few real implementations have been realized although active voltage control can in many cases decrease the total costs of a distribution network and enhance the voltage quality. This paper discusses the barriers for active voltage control and also suggests measures to overcome these barriers. Also the development process of an active voltage control method is described. (4 pages)Keeping the lights on using distributed generation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0813
Keeping the lights on for consumers during network disturbances is a major challenge for power engineers. Distributed generation can supply power close to the point of use and, although not current UK practice, many can operate in isolation of the grid supply. To achieve this, their control scheme needs to be modified for islanded operation and other system considerations need attention. Arguably the greatest challenge is reconnecting the power island to the grid supply. For this a specialist controller is presented which controls the point of reclosure of the breaker used to reconnect the two networks. (4 pages)Study on digital controller of multi-task interleaving parallel BUCK modules
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0643
Take three parallel Buck modules for example. By adopting master-slave current sharing technology, a digital controller is designed on the basis of DSP56F807 and μC/OS II operating system. As the key parts of the research, interleaving parallel technology and current sharing strategy, as well as the scheduling and division of the task modules, is introduced in detail. The parallel power system and the design of real-time multi-task software play a significance role for the improvement of the reliability of the system.Control strategies for smart low voltage grids - the Project DG DemoNet - Smart LV Grid
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0824
Upcoming challenges for LV grids include a high penetration of distributed energy resources and electric vehicles. The project “DG DemoNet - Smart LV Grid” aims to enable an efficient and cost effective use of existing grid infrastructures based on a three-step concept: intelligent planning, on-line monitoring and active LV grid management. Communication-based systems for automatic control concepts for low voltage grids are developed and demonstrated in pilot installations. This paper describes the results of the first phase within research project. The consortium out of distribution system operators, research institutions and industry partners have defined a set of control strategies for active low voltage grids. (4 pages)On-load voltage regulation in the low voltage grid
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0745
In the electrical distribution grids the complexity of power flow increases due to increasing penetration with small and distributed power generation plants. In the future distribution system operators (DSOs) are requested to build up an efficient and up to date grid infrastructure by integrating the end consumers with their fluctuating power generation, their load and their storage capabilities in the system. In most European countries government subventions and the obligation to connect small solar and bio mass power generation lead to necessary extensions and strengthening of the LV grids. Depending on the generation and load scenarios in the LV and MV grids, a fluctuation of the power flow is expected, which can even result in back-feeding power into the MV and HV grid. This causes large voltage fluctuation in the grid. One possibility to remain compliant with the reduced voltage range of +/-10% according EN 50160 in grids with a high share of distributed generation is the use of a regulated distribution transformer. Especially in the case of homogeneous grids this measure is promising. Thereby the challenge is the development of an on-load voltage regulation for distribution transformers by keeping the accustomed performance and dimensions to ensure the changeability und comprehensive operation wherever it's needed. Siemens AG has developed a regulated distribution transformer with an on-load voltage regulation on the low voltage side which fulfills all these requirements. Together with the German DSO E.ON Mitte AG a functional model was installed and field tested in an existing grid. (4 pages)Voltage control in low voltage systems with controlled low voltage transformer (CLVT)
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0821
The rapidly growing penetration of Germany's distribution grids with all forms of DG causes a high pressure on voltage stability according to several normative guidelines. Beside conventional network reinforcements increasing short-circuit-power, new technical alternatives awake interest. One approach is the CLVT, an innovative downsizing of substations voltage regulation. This paper investigates the potential for voltage control of this new technology as well as the possibility to increase the DG connection capacity of LV networks with respect to step voltage, number of operating positions and which measurements are used as reference value for the controller. The benefits and disadvantages of an mono- and multi-sensor operation mode will be discussed. Furthermore possible interactions between several CLVTs connected to one single grid are analysed. (4 pages)Voltage profile quality of conformance evaluation with process capability analysis in the presence of distributed generation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0827
Quality is defined as meeting the requirements of the customers, so it is vital for distribution companies to provide electric power with specified voltage in all time for all customers in the competitive energy market. In the absence of distributed generation (DG) it is possible to control voltage profile with proper network design and optimized setting of high voltage transformer online tap changers, but in the presence of DG, especially renewable resource like photovoltaic panels and wind turbines, the voltage profile is affected by stochastic behaviour wind velocity, sun light and DG owners decisions. In this study process capability analysis and statistical control chart have been used together to evaluate of distribution system capability to maintain voltage in design level and to detect abnormalities in voltage profile in the presence of distributed generation. (4 pages)Optimal short term operational planning for distribution networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0718
Short term operational electricity distribution network planning (to be distinguished from long-term planning) involves activities aimed at anticipating network constraints and improving network performance within the existing level of basic infrastructure. This concept is commonly used by Transmission Network Operators in order to anticipate and optimize their network operating point at a national and regional level. Based on the development of local load and generation forecasts tools, for which accurate meteorological forecast is required, short-term operational planning decisions in distribution networks will be made in the near future of operational time (Week-1, Day-1). In addition, real-time network automation functions are used in order to solve the few problems which could not be anticipated. This paper introduces EDF R&D and ERDF's vision of the French Distribution System Evolution and presents the DSO induced needs. The voltage control function is used as an example in order to describe the different time sequences. (4 pages)Impact of DER integration on the cyber security of SCADA systems - the medium voltage regulation case study
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0808
The operation of active distribution grids with high penetration of Distributed Energy Resources, connected to Medium Voltage bars and feeders, requires the implementation of new Medium Voltage regulation functions. Assuming that this control function is best positioned in the primary substations of the control hierarchy, the paper presents the architectural changes occurring at both the centre and the substation control levels. Possible cyber risk scenarios and mitigation countermeasures of the new SCADA architecture are discussed, in compliance with the IEC communication standards and the IEC/NIST cyber security technical recommendations related to the smart grid sector. (4 pages)The effect of different control modes and mixed types of DG on the non-detection zones of islanding detection
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0823
Loss of mains protection (LOM) is among the most challenging issues related to the integration of distributed generation (DG). This paper presents simulation studies on the effect of multiple DG units on LOM protection. The results reveal an operational risk related to the active LOM detection methods. The effect of voltage droop control of the DG on the form of the NDZ is also studied. (4 pages)Development of voltage regulation method including voltage control by switching capacitors of customers in autonomous demand area power system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0773
In 6.6kV power distribution system of Japan, the introduction of many distributed power generations (DGs) is expected. Under such circumstances, power flow congestion and voltage fluctuation on distribution lines caused by varied output of the DGs will occur. This will result in failure to maintain power quality and supply reliability by conventional power system management. Especially, in residential, commercial and industrial mixed area of Japan, the distribution system voltage will rise at the end of feeder because of reverse power flow by photovoltaic (PV) generations and capacitors (SC) for power factor control by 6.6kV customers. We have proposed a new power supply system referred to as the Autonomous Demand Area Power System (ADAPS). ADAPS may be in the loop formation, in addition to the conventional tree branch formation. We try to establish network technology and operation management technology of ADAPS, and identify its effectiveness. In this paper, we studied voltage regulation method by using Static Var Compensator (SVC), Step Voltage Regulator (SVR) and customer's SCs controlled to improve power factor and to regulate voltage at connection point as power distribution system in transition period from conventional system to ADAPS. (4 pages)Optimisation of HV/MV-transformer-voltage-control in distribution networks with a high proportion of distributed generation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0734
The power supply from many small decentralised power generation plants (DPG) is increasingly influencing the voltage quality in the distribution networks. The further expansion of the decentralized energy plants is expected to lead to a worsening of the situation. The need to further expand the German distribution network, a need forecast by the BDEW (the German Energy and Water Authority) has given rise to the necessity to look for fast, cheaper and innovative solutions to reduce the negative effects on the power supply of the power generation plants on the MV and LV network levels. Within the framework of a pilot project carried out by the LEW Verteilnetz GmbH, it was examined whether the maintenance of the voltage level in the MV network could be improved with the help of an optimised voltage regulator of the HV/MV transformer, at the same time remaining in the stipulated limits. The LEW Verteilnetz GmbH (LVN) is a regional network operator in Bavaria and a subsidiary of Lechwerke AG based in Augsburg. The network area of Lechwerke includes Bavarian-Swabia as well as parts of Upper Bavaria. (4 pages)The increase of distributed generation on enel distribuzione's network: state of the art, actions and strategies for integration
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0870
In recent years the scenario of the Italian electrical system is characterized by the exponential growth in connections of renewable sources power plants, which is actually revolutionizing the network planning and operation criteria. In the current legislative and regulatory framework, renewables have the right to be connected by the least cost technical acceptable (LCTA) solutions. Furthermore they have priority of dispatching and no production forecasts are required. For these reasons it is necessary to control and measure in real-time the power injected into the network by each generator in order to regulate and limit the power when required for the electrical system stability. The high number of ongoing connection requests is increasing the potential saturation of the network, with the result of a close coordination with the TSO. This paper shows, in the first part, the increase of distributed generation - in terms of requests and connections - on Enel Distribuzione's network. In the second part are described Enel Distribuzione's innovative technical solutions in order to better integrate the DG ensuring a safe and effective operation of the whole electrical system, with the aim, in a desirable new legislative and regulatory framework, to enable DG “active” participation. At last, many projects are now developed in order to study new methods of network operation and upgrades. (4 pages)Implementation of smart grid environment in Green Campus project
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0825
The Aim of this paper is to introduce the implementation of Smart Grid environment in the Green Campus project. Green Campus project is a combination of existing low voltage customer network with smart grid elements. The goal of this project is to have an actual field implementation of smart grid with load control, distributed generation and energy storages. The Smart Grid recognizes the units connected to the system, enabling data gathering from these units via the communication line. Demonstration grid is capable of controlling loads and energy storages to limit consumption spikes as well as reduce energy costs by optimising the energy management system? with the optimisation of an energy management system. (4 pages)Integrating larger RES share in distribution networks: advanced voltage control and its application on real mv networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0826
The paper describes the algorithm that supports increasing the hosting capacity of the network by means of Voltage control of Medium Voltage feeders in presence of storage units. Starting from description of main characteristics and simulation results, the document depicts the future application of the algorithm in a real MV network. (4 pages)Energy resource scheduling considering reactive power management
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0802
The reactive power management is an important task in future power systems. The control of reactive power allows the increase of distributed energy resources penetration as well as the optimal operation of distribution networks. Currently, the control of reactive power is only controlled in large power units and in high and very high voltage substations. In this paper a reactive power control in smart grids paradigm is proposed, considering the management of distributed energy resources and of the distribution network by an aggregator namely Virtual Power Player (VPP). (4 pages)Voltage control of active distribution networks by means of dispersed generation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0829
The aim of this paper is to analyze how the dispersed generators can be used to effectively control the voltage of the distribution network. The technical and economical viability of this proposal can be assessed throughout a systematic analysis of how the voltage of the point of common coupling (PCC) increases as a function of the injected active power, and the required reactive power needed to maintain the voltage of the PCC to a given value. (4 pages)Decentralized intelligent SCADA for intelligent controlling and DG integration in the electric distribution grid
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0857
The Greater Tehran Electricity Distribution Company (GTEDC) is actively pursuing more and more developments to achieve its visions as a smart grid. In this paper the developments of SCADA systems in GTEDC operation area is represented. It includes the philosophy and architectural design of different levels of smart grid vision in GTEDC, their interactions, SCADA software structure, and communication infrastructure. Moreover, the implemented and pilot projects on SCADA, automation, and DG interconnection are explained by details. (4 pages)Voltage control challenges and potential solutions for largescale integration of PV resources in LV networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0819
In this paper we illustrate PV single inverter response to voltage rise in LV networks and simulate multiple PV cascading that may result from inverter's response. We then address potential solutions to mitigate the drawbacks of simplistic control approaches, such as reinforcing the network, shifting supply phases, and implementing enhanced control processes. We elaborate on the framework of such control processes and identify main implementation challenges to make them effective. (4 pages)Real time voltage control in distribution network considering renewable energy sources
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0793
Nowadays, fossil fuels reduction, environmental impacts, transmission line and substation construction costs, economic and technical efficiency, are leading to increase distributed generation such as renewable energy sources (RES). RES are connected to distribution networks (DN), so we don't need to transmission equipment. But the reverse power flow from RES causes to change operation method. As we know weather condition have influence on output power in RES. Conventional control methods are not useful for operation and bus voltage variation damage equipment of network and customer. So we see voltage control is important in DN with RES. So developing in communicating, smart sensors and distribution network automation is made possible for real time control. In this paper we propose a real time voltage and reactive power control in distribution network considering RES. Also fuzzy sets theory is combined with partial swarm optimization algorithm to solve the multiobjective voltage control problem. (4 pages)Investigating the potential to maximise wind penetration on distribution networks through active control and the implications for network users and operators
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0803
Meeting Irish wind generation targets had lead to very high penetrations of embedded wind generation on distribution networks and will continue to do so over the coming years, Current firm connection policy and little or no use of active voltage control from wind farms requires network reinforcement such that generation can output at its Maximum Export Capacity (MEC) under all network conditions (minimum demand, regular and contingency network configuration) regardless of the frequency of their occurrence. ESB Networks, the Irish distribution system owner and operator, has undertaken an innovative field trials to investigate the potential for active voltage control from wind farms can facilitate increased hosting capacity for generation on existing networks and aid network management in the presence of distributed generation. This paper looks at the application of a range of voltage control strategies including active restriction, demand management and wind turbine reactive control for these purposes, through investigating the potential export which could be achieved on an existing network were such mechanisms employed. (4 pages)Interface for energy regulation: An application for distributed generation control
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0810
In this paper the main technical features of IRE (Interface for energy regulation) are presented. It is a control device specified by Enel Distribuzione in order to support voltage regulation and power flow control on MV "active" networks, in the scope of some demonstrative/pilot projects in Italy. IRE performs its functions adjusting active and/or reactive energy of private power plants connected to the MV distribution network. These functions are defined independently from the specific device that actuate the requested variation of power parameters (inverters, storage systems, capacitors, etc). The Distributor can dynamically impose the energy flows conditions for each MV client sending this request to IRE devices along the feeders. IRE will process the request actuating the settings in a reasonable time span. The results of simulations are also described, to demonstrate the effectiveness of the implemented algorithm. (5 pages)Experimental validation of control strategies for a microgrid test facility including a storage system and renewable generation sets
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0830
The paper is aimed at describing and validating some control strategies in the SYSLAB experimental test facility characterized by the presence of a low voltage network with a 15 kW-190 kWh Vanadium Redox Flow battery system and a 11 kW wind turbine. The generation set is connected to the local network and is fully controllable by the SCADA system. The control strategies, implemented on a local pc interfaced to the SCADA, are realized in Matlab-Simulink. The main purpose is to control the charge/discharge action of the storage system in order to present at the point of common coupling the desired power or energy profiles. (4 pages)Evaluation and error minimization of dynamic short time load forecasting model with control charts and process capability analysis in the presence of distributed generation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0842
Short time load forecasting (STLF) is a pivotal concept in energy marketing, therefore, regulatory has defined penalty for load forecasting errors, which disturb energy market balance. Distributed generation (DG) has two effects on STLF models: first, in the presence of DG these models inevitably entail non-repeating data as well as load trends, and second, the share of DG in power generation is not constant. Therefore, the STLF model should be evaluated and improved continuously otherwise model accuracy will dwindle gradually. A lot of STLF models have been developed but there isn't proper tool to assess their accuracy in the presence of DG. For controlling the impact of probabilistic behaviour of distributed generators on load forecasting, West Tehran province power distribution company (WTPPDC) combined dynamic model, statistical control chart and Process capability analysis for continual evaluation and monitoring of the STLF model. In this study WTPPDC have used process capability analysis for evaluation of forecasting capability of model and control charts for detecting out of control error and accumulative bias in prediction in the presence of DG. Quality approach to load forecasting error controlling can help distribution companies to improve their model before forecasting errors reduce their profit and business confidence. (4 pages)Decentralized voltage control in active MV distribution networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0796
A decentralized voltage control strategy for MV distribution networks is here proposed, which is based on the possibility at any specific node to locally estimate the voltage level variations at the neighbouring nodes through the real-time measure of the current flowing on the incoming and outgoing lines. This enables to develop voltage control strategies accounting for 3 adjacent buses although based solely on local measurements. This approach is demonstrated to improve the overall network performance while limiting the need of large investments on communication systems. (4 pages)Local voltage regulation influence on DG and distribution network
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0732
Distribution grids were initially not designed to house significant amount of distributed generation (DG). However, DSO experienced during the last few years a huge increase in penetration rate of renewables. Since DG has a major impact on the voltage level, its connection can result in voltage constraints that limit its integration or lead to grid investments. In such situations, using voltage control may relieve some constraints with no or limited investments. Higher penetration rate of DG will make generation facilities' contribution to voltage control a necessity in a near future, in addition to existing control devices (on-load tap changers). (4 pages)Improving power quality in distribution feeders with high PV penetration through inverter controls
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0749
Voltage fluctuations caused cloud transients in distribution systems with a high level of distributed photovolaic systems is of concern to electric utility companies since this can lead to power quality issues. This article proposes a scheme that can minimize this problem by allowing grid-tie inverters to generate controllable amounts of reactive current in a way to neutralize the change in active current. Inverter oversizing is not required by the implementation of this method. The performance of this technique is verified through computer simulations using PSCAD software. (4 pages)Centralized voltage-var regulation in distribution network
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0713
This paper presents centralized voltage-var control solutions for capacitor banks, step-voltage regulators, load-tap changers, and reclosers. These systems include communications, a centralized automation platform, and software to control voltage profile and reactive power flow. (4 pages)Micro grid control structures for better integration of renewable energy
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0776
Driven by the increasing need to expand grid capacities due to the sustained integration of distributed renewable energy sources (especially photovoltaic generation in low voltage grids), solutions for an economic justifiable approach are needed. The majority of the provided options by the OEMs lead to an increased amount of data and control complexity in order to operate the additional equipment. To avoid dependencies on a higher control instance and to reduce the needed effort to operate a distribution grid covering a large area, local control strategies could provide a solution. In a small village, the EnBW electricity company runs a pilot project and tests different options for low voltage (L V)-grid load shedding. To implement and validate control structures under real conditions is an inherent part of the research program. This paper shows the general approaches chosen for the design of a control system as a local micro grid, as well as the first results from the phase of practical testing. (3 pages)Distributed generation forecast as input to capacitor banks management in distribution networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0785
Reactive energy control has an important role in the electric system, once it is a tool which enables a more efficient management of the Distribution Network (DN). Nowadays, in Portugal, the balance between active and reactive energy is performed daily at REN EHV/HV substations fulfilling ERSE (Portuguese Regulator) rules. Failure to comply these rules implies financial penalties for the Portuguese DSO, EDP Distribuicão. Up to now, the capacitor banks management model used by Portuguese DSO was based on local historical demand at the HV/MV substations. This methodology is only valid for passive networks with no DG. This paper aims to check the feasibility of including DG forecasting into the proposed capacitor banks management model at networks with large concentration of DG. To validate this study, a comparison (considering actual generation patterns) between the results obtained by both the historical and the proposed model will be conducted. (4 pages)Utilizing local resources to participate in power balance: a concept and its realization
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0791
Integrating large amount of low-inertia and intermittent renewable generation into the power system has increased the occurrence probability of power system imbalance brought about by large disturbances in short time scale and reduced the control capability of the power system under those disturbances. The continually increased electric vehicles (EVs) connected to the power grid may be capable of responding to those disturbances and contributed to the power balance by utilizing the fast-response, continuously regulating and power decoupling control capability of the power electronic charging interfaces. In this paper, different control schemes have been proposed to respond to the disturbances originated from distribution systems and the transmission systems respectively by regarding the electric vehicles as power support resources and considering the characteristics of the distribution network. A typical 11-kV 38-node system has been presented and tested to validate the effectiveness of utilizing the electric vehicles as power balance control resources and the related control schemes. (4 pages)An agent-based control system for outage management in distribution network in presence of distributed generation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0752
In this paper, a new control scheme based on the multiagent system concept is introduced which is completely compatible to the today's smart grids with presence of distributed Generations. The aim here is to define an agent-based system, and accordingly a suitable procedure, to improve the fault locating, isolating and restoration process in a distribution network. The proposed system, then, is applied to a network with real characteristics in order to be assessed and evaluated based on its performance compared to some other outage management systems. (4 pages)Coordinated voltage control in distribution systems with DG - control algorithm and case study
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0890
Distributed generation (DG) in medium voltage distribution networks has become widespread during the last years. Distribution networks are normally planned and built to cope with decreasing voltage from the substation along the feeders. With a high DG penetration the power flow can be reversed in some feeders during some time periods and thus the voltage increases along the feeder. In this paper an improved voltage control algorithm for a more active voltage control in medium voltage networks is presented and tested by simulations in an existing network. By using coordinated control of the DG units' active and reactive power as well as the on-load tap changer (OLTC), the DG hosting capacity can be increased without expensive network reinforcement. In the test case it was possible to increase the DG capacity from present 13 MW to 38 MW without the need of network reinforcements. (4 pages)Frequency control of microgrids by demand response
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0708
This paper investigates the use of electricity demand response as a new measure for fast reserves inside of an autonomous (islanded) microgrid during different operating conditions including frequency controlled disturbance and normal ones. It is worth noting that demand response programs using under-frequency relays to shed the loads is used in the past, but these programs have, however, mainly focused on large-size industrial loads. This paper proposes novel approaches to stabilize the frequency in normal and emergency conditions based on the new bilateral communicating infrastructure within a microgrid. Demand reserves are used based on a pre-scheduled scenario instead of shedding loads or applying generation resources, hence the ease and priority of the customers are guaranteed and full exploitation of generating resources are provided. (4 pages)Demonstrating enhanced automatic voltage control for today's low carbon network
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0770
Increased amounts of distributed generation and disruptive loads such as electric vehicle charging and heat pumps will increase the importance of Distribution Network Operators (DNOs) actively managing voltage on their network. Dynamic voltage control is commonplace at higher voltages; however, tighter control of voltages further into the distribution network is likely to be necessary. This paper provides an overview of the Customer Led Network Revolution (CLNR) project and the trials involving Enhanced Automatic Voltage Control (EAVC). The proposed control methodology is discussed with a description of the Grand Unified Scheme (GUS) control system. (4 pages)Benefit assessment of energy storage for distribution network voltage regulation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0872
The paper describes some results of a preliminary analysis of a pilot project for the exploitation of energy storage devices on the distribution system. The storage has been used for load levelling and voltage support and its performances have been obtained with software simulations based on real data. Emphasis has been placed on the importance of the optimal sizing and siting of the storage device. (4 pages)Control architectures to perform voltage regulation on low voltage networks using DG
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0884
Increasing levels of small scale generation units connected to lower voltage levels are causing problems on distribution network operation. The implementation of smart grids enables the operator to have an extended view over the system operational parameters and even to control active participants (loads and generators). Voltage profile volatility is one of the main problems associated with DG units connected to LV networks. The adequate architecture, technical requirements and algorithms for voltage regulation are addressed on this paper. (4 pages)Object-oriented modeling of a power network for model-based voltage control
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0833
This paper deals with the design of dynamic regulators for voltage control in Medium Voltage feeders with Distributed Generators, which can be used as active control elements. A modular object-oriented simulation environment has been developed in Matlab<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">®</sup>/Simulink/Simscape. This tool has been used for the design and validation of a control structure made by control loops acting at different levels. Specifically, two control structures are synthetized: the first one is made by standard PI-PID regulators, while the second one relies on the Model Predictive Control (MPC) approach. (4 pages)Active intelligent distribution networks - coordinated voltage regulation methods for networks with high share of decentralised generation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0820
This paper describes several voltage regulation approaches and strategies for distribution networks for achieving a cost-effective integration of high shares of distributed generation by an optimal utilization of already available network capacities. The voltage regulation methods are examined by their theoretical potential using an approach with generic networks in a first step. Afterwards case studies for their application in a real rural low voltage (LV) network with different scenarios for the installation of new photovoltaic (PV)-systems are carried out. Information about the pilot test phase applying these voltage regulations methods is provided as outlook. (4 pages)Voltage regulation in distribution grids with high ratio of distributed generation units
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0897
Distributed generation - especially from renewable energy sources - poses new challenges, the most significant being voltage band violation during high infeed low-load times. This paper investigates the potential of direct voltage control by controllable distribution transformers (MV/LV transformer with on load tap-changer) and indirect control by means of power inverters featuring reactive power support. (4 pages)High efficiency standalone photovoltaic system using adaptive switching of an interleaved boost converter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0329
Photovoltaic generation is gaining increased importance as a power source in many applications. However, energy conversion efficiency is an important factor for the long term feasibility of these systems. Significant work has been carried out into improving the effectiveness of solar arrays in the last 20 years. In addition, there has been substantial research into novel power converter topologies for maximum energy efficiency. However, in photovoltaic applications, even the most promising power converter topologies do not necessarily guarantee optimum performance under all operating conditions. For example, the efficiency of the power conversion stage may be excellent during periods of high irradiance, but significantly lower in poorer light conditions. This work attempts to address this problem, by seeking to achieve higher energy conversion efficiency under sub- optimal conditions. In this paper, stand-alone photovoltaic systems using dc-dc converters are considered. A novel adaptive control scheme is proposed to maximise system efficiency over a wider range of real-time operating conditions. (7 pages)