An overview of the present grid codes for integration of distributed generation (original) (raw)
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Integration of distributed generation to Grid
This paper considers the probable operating problems and challenges in connecting distributed generation to low-and medium-voltage electric power grids. ABSTRACT | In today's distribution grids the number of distributed generation (DG) units is increasing rapidly. Combined heat and power (CHP) plants and wind turbines are most often installed. Integration of these DG units into the distribution grid leads to planning as well as operational challenges. Based on the experience of a Dutch distribution system operators (DSO), this paper addresses several possibilities to handle grid planning issues. Effects on voltage control, grid protection, and fault levels are investigated and described. These aspects are illustrated with the aid of simulations on an existing distribution grid. It is demonstrated that in compact distribution grids voltage control problems and blinding of protection are not likely to occur and that false tripping and fault level have to be considered carefully.
Integrating distributed generation into electric power systems
It is now more than a decade since distributed generation (DG) began to excite major interest amongst electric power system planners and operators, energy policy makers and regulators as well as developers. This paper presents an overview of the key issues concerning the integration of distributed generation into electric power systems that are of most interest today. The main drivers behind the focus on DG integration, especially of the renewable type, in many countries around the world are discussed. A synopsis of the main challenges that must be overcome in the process is presented. Particular emphasis is placed on the need to move away from the fit and forget approach of connecting DG to electric power systems to a policy of integrating DG into power system planning and operation through active management of distribution networks and application of other novel concepts. The paper also analyses the repercussions in transmission system operation and expansion that result from the connection of large amounts of DG of different energy conversion systems focusing on issues related with impacts in steady state operation, contingency analysis, protection coordination as well as dynamic behaviour analysis. A discussion on the possibility of provision of ancillary services by DG is also included. Some results from studies performed in the interconnected Portuguese transmission system are presented and discussed. Some of the opportunities that could be exploited in support of the integration and hence greater penetration of DG into electric power systems are also explored.
Electric Power Systems Research, 2007
It is now more than a decade since distributed generation (DG) began to excite major interest amongst electric power system planners and operators, energy policy makers and regulators as well as developers. This paper presents an overview of the key issues concerning the integration of distributed generation into electric power systems that are of most interest today. The main drivers behind the focus on DG integration, especially of the renewable type, in many countries around the world are discussed. A synopsis of the main challenges that must be overcome in the process is presented. Particular emphasis is placed on the need to move away from the fit and forget approach of connecting DG to electric power systems to a policy of integrating DG into power system planning and operation through active management of distribution networks and application of other novel concepts. The paper also analyses the repercussions in transmission system operation and expansion that result from the connection of large amounts of DG of different energy conversion systems focusing on issues related with impacts in steady state operation, contingency analysis, protection coordination as well as dynamic behaviour analysis. A discussion on the possibility of provision of ancillary services by DG is also included. Some results from studies performed in the interconnected Portuguese transmission system are presented and discussed. Some of the opportunities that could be exploited in support of the integration and hence greater penetration of DG into electric power systems are also explored.
International Journal of Renewable Energy Development
Owing to liberalization of electricity market, technology evolution, energy security, environmental issues and growing concerns of energy cost, the penetration of distributed energy units in distribution network is increasingly observed worldwide. Penetratingrembedded generation, or distributedrgeneration (DG), in powerrdistribution grid requires asnumber of issues to be considered, such as definition of DG, rating of DG, the best DG technology etc. This paper presents an extensive critical review of various dimensions of distributed generation (DG) including definitions, generation technologies and their status, impact on distribution network performance etc. The study also presents comparative study between the various technologies in terms of most important technological characteristics of each DG technology. The policy makers, utility regulators and DG planning engineers can use this critical review, withoutigoing through complicatedicomputations, as guidelines to makeipolicies,...
A Review on Distributed Generation Definitions and DG Impacts on Distribution System
Rapidly increasing the power consumption and shortage in generating and transmission capacities have set the trend towards the Distributed Generation (DG) sources. Still there is not a universal definition of DG. This paper discusses the different definitions proposed in the literature. Further DG system to become a major stake holder in the current power scenario it needs to be connected with the existing grid system. This integration will cause some technical, operational and economic impacts on distribution systems. This paper also summarizes these different impacts of DG on distribution system.
IMPACT OF DISTRIBUTED GENERATION (DG) ON THE DISTRIBUTION SYSTEM NETWORK
Power system quality is a vital issue for electricity companies and consumers of low and medium voltage. In order to reduce the dependency on producing electric energy from fossil fuel, so the distributed renewable energy technologies are becoming increasingly important in the energy supply systems of many countries. Distributed Generator (DG) units can be defined as small units that generate electric power near to the location of customers based on the renewable energy techniques, including wind energy, solar energy, and geothermal energy. Interconnecting DG to an existing distribution system provides various benefits to several entities as for example the owner, utility and the final user. DG provides an enhanced power quality, higher reliability of the distribution system and can peak shaves and fill valleys. However, the integration of DG into existing networks has associated several technical, economic and regulatory questions. This paper investigates the impact of DGs on the power system for enhancing the power system quality by improve the voltage profile and power losses reduction. This paper uses the power system IEEE-12 busses for an example to illustrate the voltage control and decreases the active and reactive power losses by adding the wind generation DGs with the distribution network.
Improved Grid Integration of Distributed Generation in Existing Network Structures
2011
Caused by rapidly increasing numbers as well as installed power of distributed generation especially in rural areas in many cases distribution grids are already close to their limit of grid integration capacity. A highly cost-efficient and short-term implementable methodology to improve grid integration capacity for distributed generation is given by enhanced transformer control concepts. The operating range, technical potentials and the economic efficiency compared to conventional network reinforcement such as installation of additional lines or cables are determined and evaluated by a voltage-level overarching probabilistic approach.
Integration of distributed resources in power systems
2011
14.4 Technical advantages of Microgrid 14.5 Challenges of Microgrid development 14.6 Management and operational issues of a Microgrid Practical analysis of the impact of wind farms on transmission or distribution network 15.1 Power load flow model of Wind Power Plants connected to the high voltage grid 15.2 A short circuit model of WPS integrated with HV grids 400/220/110 kV 15.3 Modeling of Wind Farms in the Load Flow Analysis at a distribution MV network 15.4 Short-circuit model of WPS connected to MV grid 15.5 An example of the wind turbines impact on MV distribution This book deals with the basic concept, generation technologies, impacts, operation, control and management aspects, and economic viability and market participation issues of active distribution networks with DER in a broad perspective. Chapter 1 and 2 discusses the basic concepts of distributed energy resources and active distribution networks, their needs, technical advantages and challenges, socioeconomic impacts and several management and operational issues. Chapter 3 discusses the basic principles of operation and diagrams of connection of dispersed generators into electric power system. Chapter 4 discusses the technical impacts of DER concepts. DER has enormous impact on main grid operation and its customers. This chapter covers aspects of electricity generation and utilization, process optimization, and electricity market reforms to accommodates DER for their potential economical benefits. Major issues like impacts on distribution system, emission reduction, communication infrastructure needs, ancillary services, protection coordination , etc., have also been discussed in detail. Chapter 5 discusses the technical features of DER and modeling of active distribution. network and their applicability in integrated operation of the DER with the main power utility. It also details how and to what extent the operational needs may be taken care of by the DER technologies. Chapters 6 and 7 deal with the voltage impacts and short-circuit current impacts of DER, respectively. Chapters 8 and 9 discus the dispersed generator contribution to voltage regulation and frequency regulation in electrical power system, respectively. Chapter 10 concentrates on stability analysis. There is a limit of active and reactive power generation, which must not be violated without loss of synchronism of DG. If any generator does not remain in synchronism with the rest of the power system, large circulating currents occur and the following action of relays and circuit breakers removes the generator from the system. Chapter 11 discusses in detail the protection systems in DER, which have quite different protection requirements as compared to conventional distribution systems. Chapter 12 discusses power quality and reliability issues of DER and active distribution networks. Chapter 13 discusses and the technical features of DER and stand-alone DER installations. Chapter 14 discusses the basic concepts of Microgrids and active distribution networks, their needs, technical advantages and challenges, socioeconomic impacts and several management and operational issues. In Chapter 15 there are many sample calculations and design examples, which help to illustrate the techniques and facilitate their application. 1.3.3 Voltage Profile Issues Voltage profiles along a loaded distribution network feeder are typically such that the voltage level is at maximum c1ose to the distribution network transformer busbar, and the voltage drops along the length of the feeder as a result of the load connected to the feeder. Voltage drop is generally larger on rural networks, which are commonly radial networks with feeders covering long distances with relatively low-current-capacity conductors, especially at the remote ends of the feeders. The distribution transformer, feeding the distribution network, with a tap-changer, which controls the setting of the busbar voltage. The tap-changer will be set to ensure that, under maximum feeder loads, the voltage drop along a feeder does not result in voltage levels falling below the lower of the statutory voltage limits. DG along a distribution feeder will usually have the effect of reducing the voltage drop along the feeder, and may lead to a voltage rise at some points, which could push the feeder voltage above the statutory voltage limit. Voltage rise is generally more of a problem on rural radial networks than on interconnected or ring networks The excessive voltage rise can be initiated by relatively small amounts of DG due to the high impedance of the conductors since these feeders are often operated c1ose to the statutory upper voltage limit to counter the relatively large voltage drop over the length of such feeders. Voltage rise may be reduced by:
DISTRIBUTED GENERATION: ISSUES CONCERNING A CHANGING POWER GRID PARADIGM
Distributed Generation: Issues Concerning a Changing Power Grid Paradigm Scott G. M. Therien Distributed generation is becoming increasingly prevalent on power grids around the world. Conventional designs and grid operations are not always sufficient for handling the implementation of distributed generation units; the new generation may result in undesirable operating conditions, or system failure. This paper investigates the primary issues involved with the implementation of distributed generation and maintaining the integrity of the power grid. The issues addressed include power flow, system protections, voltage regulation,