Showing papers on "Blackout published in 2004"

Structural vulnerability of the North American power grid

Abstract: The magnitude of the August 2003 blackout affecting the United States has put the challenges of energy transmission and distribution into limelight. Despite all the interest and concerted effort, the complexity and interconnectivity of the electric infrastructure precluded us for a long time from understanding why certain events happened. In this paper we study the power grid from a network perspective and determine its ability to transfer power between generators and consumers when certain nodes are disrupted. We find that the power grid is robust to most perturbations, yet disturbances affecting key transmision substations greatly reduce its ability to function. We emphasize that the global properties of the underlying network must be understood as they greatly affect local behavior.

Final report on the August 14, 2003 blackout in the United States and Canada : causes and recommendations

Abstract: This final report by the U.S.-Canada Power System Outage Task Force examines the electricity system before and during the massive power outage on August 14, 2003 which affected approximately 50 million people in the Midwest and Northeast United States and Ontario, Canada. The report identifies the causes of the outage and why they were not contained. It also gives recommendations to prevent or minimize future blackouts, some of which include implementing reliability standards and increasing the physical and cyber security of the network. The four group causes for the blackout have been identified as: (1) inadequate system understanding, (2) inadequate situational awareness, (3) inadequate tree trimming, and (4) inadequate reliability coordinator diagnostic support. This final report covers work done by 3 working groups which focused on the electric system, security and nuclear facilities. The chapters of this report dealt with the following issues: the North American electric power system and its reliability organizations; causes of the blackout and violations of North American Electric Reliability Council (NERC) standards; preconditions for the blackout with reference to the northeastern power grid before the blackout; how the blackout began in Ohio; the cascade stage of the blackout; the August 14 blackout compared with previous major North American outages; performance of nuclear power plants affected by the blackout; and, physical and cyber security aspects of the blackout. The report indicates that the loss of FirstEnergy's overloaded Sammis-Star line triggered the cascade. Its 345-kV line into northern Ohio from eastern Ohio began tripping out because the lines were in contact with overgrown trees. The loss of the line created major and unsustainable burdens on lines in adjacent areas. The cascade spread rapidly as lines and generating units automatically took themselves out of service to avoid physical damage. The blackout had many contributing factors in common with earlier outages including: inadequate tree trimming, failure to identify emergency conditions, inadequate operator training, and inadequate regional-scale visibility over the power system. refs., tabs., figs.

Evidence for self-organized criticality in a time series of electric power system blackouts

Abstract: We analyze a 15-year time series of North American electric power transmission system blackouts for evidence of self-organized criticality (SOC). The probability distribution functions of various measures of blackout size have a power tail and rescaled range analysis of the time series shows moderate long-time correlations. Moreover, the same analysis applied to a time series from a sandpile model known to be self-organized critical gives results of the same form. Thus, the blackout data seem consistent with SOC. A qualitative explanation of the complex dynamics observed in electric power system blackouts is suggested.

Complex dynamics of blackouts in power transmission systems.

Abstract: In order to study the complex global dynamics of a series of blackouts in power transmission systems a dynamical model of such a system has been developed. This model includes a simple representation of the dynamical evolution by incorporating the growth of power demand, the engineering response to system failures, and the upgrade of generator capacity. Two types of blackouts have been identified, each having different dynamical properties. One type of blackout involves the loss of load due to transmission lines reaching their load limits but no line outages. The second type of blackout is associated with multiple line outages. The dominance of one type of blackout over the other depends on operational conditions and the proximity of the system to one of its two critical points. The model displays characteristics such as a probability distribution of blackout sizes with power tails similar to that observed in real blackout data from North America.

General blackout in Italy Sunday September 28, 2003, h. 03:28:00

Abstract: On September 28, 2003 the Italian power system experienced an electric power blackout. The outage affected an area with an estimated 60 million people and load variation in the continental grid from about 24000 MW at the early hours of the day, up to 50000 MW during the central part of the day. The event which caused the blackout began at 3:01:00 am and proceeded up to 3:28:00. Power was restored after three hours in the North area and during the same day in the large part of Italy. The energy not delivered amounts to 180GWh. The paper explains the major events that occurred as the blackout initiated and evolved and identifies the technical causes characterising the different phases of the process, which led to the general blackout. It lists the sequence of the interconnection loss and reconstructs the dynamic phases of unstable phenomena leading to the separation from Europe. The subsequent slow death throes of the separated Italian network with a cascade of generator tripping is also described up to final blackout.

The Italian 2003 blackout

Abstract: On September 28th, 2003, at 3:01 a.m., a fault on the Swiss power system caused the overloading of two Swiss internal lines close to the Italian border. The interconnection lines were heavily loaded by the large power import and the coordination between the system operators was not sufficient to mitigate the overload. The consequent loss of those important branches caused cascading outages of the lines interconnecting the Italian system and the remaining part of the UCTE (Union for the Coordination of the Transmission of Electricity) system. This resulted in a very sudden loss of synchronism between the Italian system and the UCTE grids, causing the loss of the whole import. The consequent power unbalance caused the frequency in Italy to decline; the automatic load shedding procedure was not able to shed load enough to balance the generation and the load, and this resulted in the blackout. The paper provides a short description of the pre-fault system operation and of the main events that triggered the blackout, identifying some of the main causes that resulted in the separation of the Italian system and the blackout. In addition, issues related to the misoperation of the Italian automatic procedure to prevent the blackout are discussed.

The unruly power grid

Abstract: Most experts agree that the major blackout that affected a large part of the North American upper Midwest and Northeast last August 14, 2003, was no anomaly and will definitely happen again. Records show that between 1984 and 2000, utilities logged 11 outages affecting more than 4000 megawatts, making the probability of any one outage 325 times greater than mathematicians would have expected. Mathematicians, engineers, and physicists have set out to explain the statistical overabundance of big blackouts. Two distinct models emerged based on two general theories of systems failure. One, an optimization model presumes that power engineers make conscious and rational choices to focus resources on preventing smaller and more common disturbances on the lines; large blackouts occur because the grid isn't forcefully engineered to prevent them. The other model views blackouts as a surprisingly constructive force in an unconscious feedback loop that operates over years or decades. Blackouts spur investments to strengthen overloaded power systems, periodically counter-balancing pressures to maximize return on investment and deliver electricity at the lowest possible cost. The mainstream view among power system engineers continues to be the answer to reliability problems is to make the grids more robust physically, improve simulation techniques and computerized real-time controls, and improve regulation. What system theorists suggest is that even if all that is done and done well, the really big outages still will happen more often than they should.

Experiential aspects of alcohol-induced blackouts among college students.

Abstract: Our current understanding of alcohol-induced memory blackouts is derived largely from research with middle-aged, hospitalized, male alcoholics In the present study, 50 undergraduate students (34 female and 16 male) with a history of at least one blackout were interviewed to gain insight into their experiences Fragmentary blackouts, in which memory for events is fragmented, were far more common than blackouts of the en bloc type, in which a period of time is simply missing from memory Most students recalled bits and pieces of events without cueing from others, yet still relied on friends, most also intoxicated themselves during the blackout period, to tell them what transpired Thinking about the fragments triggered further recall in the majority of cases Half of all subjects, more females than males, reported having been frightened by their last blackout experience Being frightened typically led to more careful drinking for several weeks or longer Characteristics of blackouts among college students in the present study are compared to the standard model of blackouts based on reports from alcoholics

Performance of "WAMS East" in providing dynamic information for the North East blackout of August 14, 2003

Abstract: The blackout that impacted the U.S. and Canada on August 14, 2003, was notable for its extent, complexity, and impact. It triggered a massive review of operating records to determine what happened, why it happened, and how to avoid it in future operations. Much of this work was done at NERC level, through the U.S.-Canada power system outage task force. Additional background information concerning the event was gathered together by a group of utilities that, collectively, have been developing a wide area measurement system (WAMS) for the eastern interconnection. Like its counterpart in the western interconnection, "WAMS East" has a primary backbone of synchronized phasor measurements that are continuously recorded at central locations. Operational data have been critical for understanding and responding to the August 14 blackout. Records collected on WAMS East demonstrate the contributions that well synchronized data offer in such efforts, and the value of strategically located continuous recording systems to facilitate their integration. This work examines overall performance of the WAMS East backbone, with a brief assessment of the technology involved. Later papers will provide a utility view of the NERC data review and its institutional implications.

Genetic epidemiology of alcohol-induced blackouts.

Abstract: Background Alcohol-induced blackouts (ie, periods of anterograde amnesia) have received limited recent research attention. Objective To examine the genetic epidemiology of lifetime blackouts and having had 3 or more blackouts in a year, including analyses controlling for the frequency of intoxication. Design, Setting, and Participants Members of the young adult Australian Twin Register, a volunteer twin panel born between January 1, 1964, and December 31, 1971, were initially registered with the panel as children by their parents between 1980 and 1982. They underwent structured psychiatric telephone interviews from February 1996 through September 2000. The current sample contains 2324 monozygotic and dizygotic twin pairs (mean [SD] age 29.9 [2.5] years) for whom both twins' responses were coded for blackout questions and for frequency of intoxication. Main Outcome Measure Data on lifetime blackouts and having had 3 or more blackouts in a year were collected within an examination of the genetic epidemiology of alcoholism. Results A lifetime history of blackouts was reported by 39.3% of women and 52.4% of men; 11.4% of women and 20.9% of men reported having had 3 or more blackouts in a year. The heritability of lifetime blackouts was 52.5% and that of having had 3 or more blackouts in a year was 57.8%. Models that controlled for frequency of intoxication found evidence of substantial genetic contribution unique to risk for the blackouts and a significant component of genetic risk shared with frequency of intoxication. Conclusions The finding of a substantial genetic contribution to liability for alcohol-induced blackouts including a component of genetic loading shared with frequency of intoxication may offer important additional avenues to investigate susceptibility to alcohol-related problems.

Voltage collapse diagnostic and ATC system

Abstract: An analysis method for an electrical power system whereby the plurality of buses are grouped into agents, family lines of agents and families of agents based on the reactive reserves depleted when the buses are loaded. Contingencies are then applied to the electrical power system. The reactive reserves are monitored, and an exhaustion factor is determined for one or more family lines in one or more families. A boundary case solution is used to assess where, why, and how the contingency causes voltage instability, voltage collapse and/or local blackout. Based on this information, the design of voltage rescheduling, active rescheduling, unit commitment, load shedding, etc., is determined that can be used as preventive, corrective or emergency controls in applications such as system design and planning, operation planning, reactive and voltage management, real time control and Special Protection System Control. Based on this information, solutions can then be applied to the power system.

Dynamical and probabilistic approaches to the study of blackout vulnerability of the power transmission grid

Abstract: The CASCADE probabilistic model for cascading failures gives a simple characterization of the transition from an isolated failure to a system-wide collapse as system loading increases. Using the basic ideas of this model, the parameters that lead to a similar characterization for power transmission system blackouts are identified in the OPA dynamical model of series of blackouts. The comparison between the CASCADE and OPA models yields parameters that can be computed from the OPA model that indicate a threshold for cascading failure blackouts. This is a first step towards computing similar parameters for real power transmission systems.

Cascade to black [system blackouts]

Abstract: This paper looks at the similarities between the August 14, 2003 blackout and the Western System collapse of 1996. It was shown that the August 14 collapse resulted from system overloading that led to voltage deterioration in the system and consequently a "fast" collapse, similar to the July 2, 1996 collapse.

Data management issues associated with the August 14, 2003 blackout investigation

Abstract: The largest blackout in the history of the North American electric power grid occurred on August 14, 2003. An extensive investigation into what happened (and why) began immediately. The joint U.S.-Canadian task force led the effort, including support from the electric utility industry and several federal agencies, e.g. the U.S. Department of Energy. The North American Electric Reliability Council (NERC) supported the task force, including particularly the electricity working group. The overall blackout investigation team drew expertise from a large number of organizations, assembled into teams to address specific attributes of the blackout. This work describes the data management issues associated with supporting the blackout investigation, beginning with the immediate response in the days and weeks following the blackout, supporting the interim report, to the long-term plans for deriving lessons learned for implementing improvements in the overall process of outage disturbance reporting. The sole focus of This work is the electricity working group activities at NERC; the security and nuclear working groups are outside the scope of this paper.

Alcoholic blackout for criminally relevant behavior.

Abstract: Some criminal suspects claim to have had an alcohol-induced blackout during crimes they have committed. Are alcoholic blackouts a frequently occurring phenomenon, or are they merely used as an excuse to minimize responsibility? Frequency and type of blackout were surveyed retrospectively in two healthy samples (n = 256 and n = 100). Also, a comparison of blood alcohol concentrations was made between people who did and those who did not claim a blackout when stopped in a traffic-control study (n = 100). In the two survey studies, blackouts were reported frequently by the person himself (or herself) and others (67% and 76%, respectively) in contrast to the traffic-control study (14%), in which blackouts were reported only when persons were involved in an accident. These results indicate that although blackouts during serious misbehavior are reported outside the court, both the denial and the claim of alcoholic blackout may serve a strategic function.

Recent blackouts in US and continental Europe: is liberalisation to blame?

Abstract: The paper starts with a detailed technical overview of recent blackouts in the US, Sweden/Denmark and Italy in order to analyse common threads and lessons to be learnt. The blackouts have exposed a number of challenges facing utilities worldwide. Increased liberalisation of electricity supply industry has resulted in a significant increase in inter-area (or cross-border) trades which often are not properly accounted for when assessing system security. The traditional decentralised way of operating systems by TSOs, with each TSO looking after its own control area and little information exchange, resulted in inadequate and slow response to contingencies. A new mode of coordinated operation for real-time security assessment and control is needed in order to maintain system security. This new mode of operation requires overcoming a number of organisational, psychological, legal and technical challenges but the alternative is either to risk another blackout or run the interconnected system very conservatively, maintaining large security margin at a high cost to everyone. The paper also includes technical appendices explaining engineering power system concepts to non-engineering audience.

The performance of North American nuclear power plants during the electric power blackout of August 14, 2003

Abstract: On August 14, 2003, an estimated 50 million people in large areas of the Midwest and Northeast US and of the Canadian province of Ontario, experienced a legendary electric power blackout This event involved some 62 thousand megawatts of electric load at more than 260 power plants in 8 US states and the province of Ontario Within less than a minute, 20 nuclear power plants tripped or disconnected from the grid, including 9 nuclear units in the US and 11 in Canada President George W Bush and then-Prime Minister Jean Chretien directed that a joint US-Canada Power System Outage Task Force be established to investigate the causes of the blackout and ways to reduce the possibility of future outages Based on 3 reports issued within the year following the blackout, this article highlights the key Task Force's findings and recommendations, with a particular emphasis given to the performance of nuclear power plants affected by the blackout, and from the author's perspective as an appointed member to the Task Force's Nuclear Working Group In fact, and most importantly, providing confirmation that nuclear power plants did not trigger the blackout or inappropriately contributed to its spread

Iran national grid blackout, power system protection point of view

Abstract: During last few years some catastrophic failures of power systems have been experienced throughout different regions of the world. Although power network blackouts had also been experienced in the past, it seems that the frequency of their occurrence has increased recently. Lack of sufficient investment in power systems accompanied with the more complex exploitation regulations could be considered as some of the consequences of the new deregulated power systems. As a result, even more system blackouts might be experienced in the future. Digital protection of power systems is proved to be a promising and flexible technology. Digital control and protection techniques accompanied with power system substation automation technology are being used more and more recently. While system restructuring is reducing power system margins and endanger system stability, the new technology offers new adaptive solutions in the forms of implementing novel concepts as well as using system wide protective defense schemes. In this paper, one of the major blackouts in the Iran national grid is studied. Some suggestions and solutions are also given which could improve the system performance during abnormal events and conditions.

A metric for quantifying the risk of blackout

Abstract: This paper addresses the problem of quantifying the risk of blackout and the need to do it fast, in real-time and for multiple off-line simulations. Is there a metric that can tell how far is a given power system state from its stability limit? But then, what is a stability limit? How to quantitatively describe such limit, or perhaps, limits, if more than one, and how to quickly determine how far is the transmission network from a state where a blackout might occur? The concept of steady-state stability reserve, introduced half a century ago to quantify the distance to instability, is also reviewed. Space and presentation time do not allow a detailed analysis, but an extensive list of references is provided to help promote further research. The main theme of this paper is particularly relevant in the aftermath of the wave of blackouts that affected utilities in US, UK and mainland Europe in 2003. The approach presented herein can help system dispatchers and reliability engineers foresee whether the transmission loading progresses, or is projected to progress, beyond the operating reliability limit.

Effects of catastrophic events on transportation system management and operations: august 2003 northeast blackout - great lakes region

Abstract: This report documents the actions taken by transportation agencies in response to the August 14, 2003 blackout that affected the Northeastern United States. It is part of a larger effort to examine the impacts of catastrophic events on transportation system facilities and services and the role of intelligent transportation systems (ITS) in emergencies. It also highlights the importance of good communications between transportation agency staff and the public safety officials who are the first responders during catastrophic events. The findings documented in this report are a result of the creation of a detailed chronology of events in the Great Lakes Region (principally Detroit and Cleveland metropolitan areas), a literature search, and interviews of key personnel involved in transportation operations decision-making during the blackout.

Estimating failure propagation in models of cascading blackouts

Abstract: We compare and test statistical estimates of failure propagation in data from versions of a probabilistic model of loading-dependent cascading failure and a power systems blackout model of cascading transmission line overloads. The comparisons suggest mechanisms affecting failure propagation and are an initial step towards monitoring failure propagation from practical system data. Approximations to the probabilistic model describe the forms of probability distributions of cascade sizes.

A Technique for the Standing Phase-Angle Reduction in Power System Restoration

Abstract: Blackout occurrences could cause devastating circumstances in power systems. Experience shows that the execution of power system restoration would require certain expertise and understanding of power system characteristics. One of the critical issues in power system restoration is the possible excessive phase angle difference between two buses which are to be connected by a transmission line. If the standing phase-angle is larger than the synchrocheck relay setting, then the circuit breaker would not be allowed to close. Correspondingly, instability could result in power systems if an attempt is made to force the closing of the loop. This article describes a simple and reliable approach to reduce the standing phase-angle difference. This approach is based on the rescheduling of power generation to achieve the desired reduction in standing phase-angle. The proposed approach is much more reliable than the time consuming method of trial and error that is being prescribed in practice. The results of the appli...

Blackout from the system operators' perspective

Abstract: Root causes of the blackout that happened on January 12, 2003 in southern part of Croatia (HR) and Bosnia Herzegovina (BH) are shown in this paper with respect to the role of the system operators. Action of the system operators during chronological sequence of the blackout events represents main topic of this paper. Root causes and consequences of the blackout are recognized and a set of countermeasures is proposed to the utilities in order to prevent its reoccurrence.

Voltage stability evaluation using the the relation between impedances

Abstract: The increasing loads, the great distances between the production and consumption centers as well as the state of the transport and distribution networks turns the electrical power system operating near its stability limit. When the system gets unstable a blackout situation may occur, which is critical to the system operator and consumers. We have recent examples in United States and Italy where the system was without power for several hours, causing serious problems in hospitals and public transportations. One of the causes of a blackout may be the voltage instability, which turns this subject widely discussed and studied. The speed of evolution of the voltage stability phenomenon allows us to analyze the problem as a static problem rather than a transitory one Kundur, P et al. (1983). This article will show one way to "measure" locally the proximity of the system to the voltage stability limit.

Analysis on blackout of interconnected north america power grid occurred on aug. 14,2003 from the viewpoint of power system dispatching

Abstract: The process of blackout of interconnected North America power grid occurred on Aug. 14,2003 is described from the viewpoint of power system dispatching. The problems, which existed in the dispatcher's treatment of the emergency accident, in the automation system of control centers and in the coordination among the control centers that belong to different levels, are analyzed in detail, the measures which could be adopted to control the failures by the dispatchers during the different stages of the blackout are put forward. It is pointed out that if effective measures were adopted, this serious blackout could be avoided. The lessons which can be drawn from the blackout are summarized.

Causes, analyses and countermeasures with respect to blackout in Croatia on January 12, 2003

Abstract: Causes, analyses and countermeasures of the blackout that happened on January 12, 2003 in southern part of Croatia (HR) and Bosnia Herzegovina (BH) are presented here. First, root causes and consequences of the blackout are recognized through data analysis based on all relevant documentation obtained from different sources within HR and BH systems. Then, numerical analysis is conducted to provide additional insight during blackout evolution. Analytical findings are used to point out on available countermeasures aimed for alleviation of consequences in each of different blackout phases as well as for prevention of future incidents. A set of countermeasures is proposed to the utilities in order to prevent its reoccurrence. Role of system operators and special protection system (SPS) during chronological sequence of the blackout events are discussed in more details. project study contains results of data analysis of the blackout sequence followed by static and dynamic numerical approach. It is applied in order to mutually relate findings. The blackout was confined to southern part of Croatia (called Dalmatia) and a part of Bosnia Herzegovina which was at that time connected to the first UCTE synchronous zone. Root causes, consequences and countermeasures are analyzed in detail with respect to all relevant events recorded in collected documentation. The role of the system operators and the activation of the special protection system (SPS) during chronological sequence of the blackout events are discussed in more details. The role of the system operators is primarily analyzed

Effects of Catastrophic Events on Transportation System Management and Operations: August 2003 Northeast Blackout, New York City

Abstract: This report documents the actions taken by transportation agencies in response to the August 14, 2003, blackout throughout the Northeast. It is part of a larger effort to examine the impacts of catastrophic events on transportation system facilities and services and the role of intelligent transportation systems (ITS) in emergencies. It also highlights the importance of good communications between transportation agency staff and the public safety officials who are the first responders during catastrophic events. The findings documented in this report are a result of the creation of a detailed chronology of events in the New York City metropolitan region, a literature search, and interviews of key personnel involved in transportation operations decision-making during the blackout.

Commentary: Alcoholic blackout and allegation of amnesia during criminal acts.

Abstract: The article by van Oorsouw and colleagues presents interesting survey and experimental data, exploring the question of whether alcohol blackouts occur frequently or are used primarily as an excuse to minimize legal responsibility. The authors concluded that the results of their analysis indicated that blackouts during serious misbehavior are often reported outside the court, but the denial or claim of alcoholic blackout may serve a strategic function for the person who raises the claim. Reports of alcoholic blackouts are well documented in the psychiatric literature. Lishman notes that an alcoholic blackout consists of a dense amnesia for significant events which have occurred during a drinking episode, when at the time outward behavior perhaps seemed not disordered. Usually the gap extends for a period of several hours, but very occasionally, it may cover several days. Goodwin et al. have presented detailed descriptions of the nature of blackouts in 64 subjects. This is one of the earliest research studies of alcoholic blackouts in American psychiatry. One fourth of their patients found themselves in strange places with no recollection of how they got there. The wives of two of these patients reported that they could tell when a blackout was in progress, by their husbands’ glassy stare, belligerent behavior, or repetition of questions that showed that experiences were failing to register. These blackouts were described as en bloc and were distinguished from fragmentary memory losses, in which the subject was unaware that events had been forgotten, until he or she was told about them later. An early investigation by Tarter and Schneider explored the possibility that alcoholics subject to blackouts might have some enduring impairment of memory when sober. Their results were uniformly negative for that question, and, on a wide battery of neuropsychological memory measurements, those with the highest incidence of blackouts performed as well while sober as those in whom blackouts were rare. Goodwin and colleagues demonstrated further that volunteers trained and tested while under the effects of alcohol demonstrated some reproducible findings. During periods of moderate intoxication, registration was substantially normal, but short-term memory was considerably impaired. More severe intoxication caused a significant decrease in registration and a more profound diminishment in shortterm memory. Subjects demonstrated poor ability to recall the events of the preceding day on days following moderate intoxication, and decreased recall was even more pronounced on days following severe intoxication. The diminishment of memory was also related to the duration of intoxication, in that it tended to become worse as the days of the experiment went by. Defects in 24-hour recall were also more frequent and severe. The worse the short-term memory had been, the greater the level of intoxication had been. Conversely, 24-hour recall was always normal in subjects who had shown intact short-term memory the day before. This study demonstrated further marked individual susceptibility to the same blood-alcohol level affecting each subject to a variable extent. Only 6 of the 13 subjects showed blackouts, which were defined as the ability to answer less Dr. Granacher is Clinical Professor of Psychiatry, University of Kentucky College of Medicine and President of the Lexington Forensic Institute, Lexington, KY. Address correspondence to: Robert P. Granacher, Jr, MD, 1401 Harrodsburg Rd., Saint Joseph Office Park, Lexington, KY 40504. E-mail: rgranacher@aol.com

A middleware approach for dynamic real-time software : reconfiguration on distributed embedded systems

Abstract: Dynamic software reconfiguration is a useful tool to adapt and maintain software systems. In most approaches, the system has to be stopped while the reconfiguration is in progress. This is not suitable for real-time systems. Timing constraints must be met even while the system is reconfiguring. Our approach is based on the real-time middleware OSA+. Our main objective is to be able to reconfigure one (or more) service during the run-time, with a predictable and predefined blackout time (the time the systems does not react due to the reconfiguration). Three different approaches concerning the blocking or non-blocking state of a service are presented. These approaches can be used to realize a tradeoff between the reconfiguration time and the blackout time.