Search

Microgrid (MG) is one of the practical and best concepts to provide energy access to rural communities, where electric grid extension is not techno-economically feasible. Since the trend of load consumption is not uniform with a low load factor in a rural area, the required rating of the system becomes very high. Similarly, the generation is fixed for these MGs, whereas the load increases continuously over time. Such a system faces supply deficit issues triggering a high number of interruptions that may cause frequent blackouts. Hence, rolling blackout and load clipping techniques are preferred during the peak load period in most of the rural MGs. These issues lead to an unreliable power supply and low satisfaction level of the user. This paper presents the load prioritization technique to guarantee the continuous supply for the essential loads within the rural community. A day-ahead energy allocation technique is mathematically formulated and optimized to maximize the total hours of energy served. This technique maximized the hours of energy served to the load with higher priority followed by the load with lower priorities. From this study, it is found that the proposed strategy helps to improve the hours of energy served in the overall system, by improving the state of charge (SoC) level of the battery system. The result shows that the user satisfaction level has been improved by 5% through 100% of continuity for the essential loads.

Currently, South Africa is facing an energy crisis: the existing production capacity cannot meet the growing demand for electricity. Although South Africa’s 1998 energy white paper had predicted at the time that “for an assumed demand growth of 4.2%, Eskom’s present generation capacity surplus will be fully utilized by about 2007” and stated that up to 30% of the country’s generation could come from independent power producers, the appropriate legislation was never enacted and no private generation was incorporated. In 2004 the power reserve margins dropped sharply as the economic growth accelerated. The reserve margins continue to drop below 10%, and this led to rolling blackouts (i.e., load shedding) in 2007–08. Since 2007–08, the country has been experiencing several rolling blackouts (i.e., load shedding). They go away to periodically return for longer periods and more severely each time. The crisis however has been in the making for the past three to four decades when the government of the day commenced the roll out of a massive power investment program within Eskom. The main problem is that the aging generation plants of the South African power utility, Eskom, continue to break down regularly. This is because of inadequate maintenance and operations over the years. There were high expectations that the new build program, which includes the commissioning of Medupi and Kusile, would bring an end to the energy crisis. In fact, these new generators did not leave up to expectations as they are even more unreliable than existing plants due to failed construction. Thirteen years or so after the first rolling blackout in South Africa, no adequate solution has yet been found to deal with the energy crisis in South Africa. To make the situation even more difficult, Eskom is said to be in debt and has to borrow money to service its debt. The government has suggested recently that Eskom be restructured and unbundled into three operating units, namely, generation, transmission, and distribution. The idea is to sell some of the generation plants to private companies. This should reduce cost and increase debt transparency and may lead to increased efficiencies, especially if competition is allowed. However, this idea has sparked nationwide debate among unions, economists, and experts. Some of the stakeholders such as unions are opposed to the idea of privatizing Eskom due to fear that many jobs will be lost. In this chapter we will first discuss the current energy situation in sub-Saharan African countries, then explore the reasons for the rolling blackouts and their effects on the South African economy. Next we will discuss the electricity market in a Southern Africa context, and finally we will examine the proposed electricity restructuring of the South African power utility and discuss some of the benefits and challenges in successfully achieving the restructuring.

본 연구는 고신뢰성조직의 특성을 바탕으로 9⋅15 순환단전의 기술 및 조직 실패의 원인과 발생 과정 및 그 결과를 탐구함으로써 우리나라 전력계통을 제어하는 조직의 성격을 진단한다. 그럼으로써 전력계통을 관리하는 조직이 고신뢰성조직으로 가기 위해 필요한 조직 문화와 규범 및 제도적 장치가 무엇인지를 모색하고 있다. 9⋅15순환 단전의 기술 및 조직 실패의 분설결과 의사결정도구인 Energy Management System(EMS)를 비롯한 기술적 제어능력의 결여, 경계심⋅주의력⋅상황판단의 부족, 긴급 상황 시 의사결정과정에서 절차와 조심성의 결핍 및 혼선, 정보부족으로 인한 중앙에서 분석과 현장에서 조치의 실패 등의 문제가 드러났다. 본 연구는 전력계통 운용조직들이 고신뢰성조직이 되기 위해 조직의 투명성과 기술적 신뢰성을 높이는 노력, 오류의 지속적 개선 및 학습조직의 지향, 원활한 의사소통, 실질적인 전기신뢰성 제도화 등의 행동원칙을 제안하고 있다.

This study estimates the power outage costs of the industrial sector by not only considering production loss but also the customer's inconvenience and various damages. For the estimation, we used a Type II Tobit model with firm-level survey data for 430 firms, and considered factors affecting the outage cost such as outage duration, average annual sales, and average monthly electricity consumption, among others. In addition, we analyzed the effect of the preannouncement of a rolling blackout on outage cost savings, and also examined the value of an emergency generator. From the estimation results, we found that the estimated outage cost is 1.24–1.3 times greater than the simple value of lost load (VoLL), and this difference increases when companies have emergency generator. The commercial and public service sector can reduce the outage cost the most compared to other sectors when a preannouncement is provided, and operating emergency generators can lower the outage cost in these sectors. Finally, we confirm that South Korea's rolling blackout in the predetermined order by the industry is appropriate to minimize the outage costs for the national economy when the outage is preannounced, but is not appropriate when there is no preannouncement.

Although South Korea experienced a rolling blackout in 2011, the possibility of a blackout in South Korea continues to increase due to rapid electrification. This study examines the problems of energy taxation and price distortions as possible reasons for the rapid electrification in South Korea, which is occurring at a faster rate than in Japan, Europe, and other developed countries. Further, we suggest new energy taxation and price systems designed to normalize electricity prices. In order to do so, we consider two possible scenarios: the first imposes a tax on bituminous coal for electricity generation and the second levies a tax to provide compensation for the potential damages from a nuclear accident. Based on these scenarios, we analyze the effects of a new energy system on electricity price and demand. The results show that a new energy system could guarantee the power generation costs and balance the relative prices between energy sources, and could also help prevent rapid electrification. Therefore, the suggested new energy system is expected to be utilized as a basis for energy policy to decrease the speed of electrification, thus preventing a blackout, and to induce the rational consumption of energy in South Korea.

Many manufacturing companies in China currently are suffering from a Rolling Blackout policy for the industry electricity supply which means that the government electricity is cut off several days in every week resulting in manufacturing companies illegally starting their own diesel generators to maintain production. However, the private generation of electricity is more polluting and costly than the government supplied resource. Thus, the increased price of energy and the requirement to become more environmentally sustainable exert substantial pressures on manufacturing enterprises to reduce energy consumption for cost saving and to become more environmentally friendly. Scheduling of less energy consumption critical operations during Rolling Blackout periods can help minimise the negative effect of this policy. This is a multi-objective optimisation problem as production due dates cannot be ignored and cost is not directly proportional to electricity consumption anymore. Optimal scheduling even of relatively small production orders is clearly beyond the capability of manual tools or common single objective scheduling optimisation methods. Therefore, a multi-objective scheduling optimisation method has been developed which includes reducing electricity consumption and its related cost as part of the objectives in addition to total weighted tardiness. This research focuses on classical job shop environments which are widely used in the manufacturing industry in China and the rest of the world. A mathematical model for the tri-objectives problem that minimises total electricity cost, total electricity consumption and total weighted tardiness has been developed. A specific heuristic has been devised for investigating how the Rolling Blackout policy affects the performance of existing scheduling plans. This heuristic can also be used as a remedial measurement by plant managers if they do not have access to multi-objective optimisation tools. The Non-dominant Sorting Genetic Algorithm has been used as the basis for solving the optimisation problem. Case studies based on four modified job shop instances have been studied to show the effectiveness of the proposed heuristic and the algorithm.

South Korea is experiencing a serious imbalance in electricity supply and demand, which caused a blackout in 2011. The Korean government has planned to perform a rolling blackout to prevent large-scale blackouts when the electricity supply reserve margin reaches less than 1 million kW. This study attempts to estimate the inconvenience cost of household customers from a rolling blackout by using survey data. To this end, we apply a contingent valuation method (CVM) to measure their willingness-to-pay (WTP) in order to avoid a rolling blackout, i.e. the suspension of electricity supply. In this study, we estimate the inconvenience costs stemming from both an unannounced and an announced rolling blackout. As a result, we find that the inconvenience cost of a sudden rolling blackout is estimated at 3900.67 KRW (3.56 USD) per month per household, while that of an announced rolling blackout stands at 3102.95 KRW (2.83 USD). This difference in costs shows that people place value in receiving prior notice of a blackout, and that inconvenience costs of between 166.0 billion KRW (151.6 million USD) and 174.3 billion KRW (159.2 million USD) per year can be reduced nationwide by giving households advance notice of a planned rolling blackout.

Plasma membrane PI4P is an important direct regulator of many processes that occur at the plasma membrane and also a biosynthetic precursor of PI(4,5)P2 and its downstream metabolites. The majority of this PI4P pool is synthesized by an evolutionarily conserved complex, which has as its core the PI 4-kinase PI4KIIIα (Stt4 in yeast) and also comprises TTC7 (Ypp1 in yeast) and the peripheral plasma membrane protein EFR3. While EFR3 has been implicated in the recruitment of PI4KIIIα via TTC7, the plasma membrane protein Sfk1 was also shown to participate in this targeting and activity in yeast. Here, we identify a member of the TMEM150 family as a functional homologue of Sfk1 in mammalian cells and demonstrate a role for this protein in the homeostatic regulation of PI(4,5)P2 at the plasma membrane. We also show that the presence of TMEM150A strongly reduces the association of TTC7 with the EFR3-PI4KIIIα complex, without impairing the localization of PI4KIIIα at the plasma membrane. Collectively our results suggest a plasticity of the molecular interactions that control PI4KIIIα localization and function.

Nepal, an underdeveloped country with one of the lowest energy consumption in the world suffers from chronic energy shortage. To meet unquenchable demand of energy, the country spends large amount of money to import fossil fuel and electricity. Urban centers of Nepal have emerged as the main energy consumers and largest green house gas (GHG) emitters due to increasing urbanization and changing lifestyle. Government owned utility company has failed to supply increasing demand of electricity and have resorted to long hours of rolling blackout. Use of solar power technologies can help mitigate the blackout problem as Nepal receives good solar insolation. Despite having good potential for photovoltaic solar power (PSP), its adoption is limited to rural areas due to lack of government support and higher cost. This article analyzes the electricity shortage problem and assesses the feasibility of rooftop PSP in urban areas. The assessment analyzes problems and shortcomings of current system and recommends policy changes to increase use of rooftop PSP.

This paper describes a multiple time interval ("multi-interval") parameter estimation method. The multi-interval parameter estimation method estimates a parameter from a new multi-interval prediction error polynomial that can simultaneously consider multiple time intervals. The root of the multi-interval prediction error polynomial includes the effect on each time interval, and the important mode can be estimated by solving one polynomial for multiple time intervals or signals. The algorithm of the multi-interval parameter estimation method proposed in this paper is applied to the test function and the data measured from a PMU (phasor measurement unit) installed in the KEPCO (Korea Electric Power Corporation) system. The results confirm that the proposed multi-interval parameter estimation method accurately and reliably estimates important parameters.

It has long been a significant but difficult problem to identify propagation sources based on limited knowledge of network structures and the varying states of network nodes. In practice, real cases can be locating the sources of rumors in online social networks and finding origins of a rolling blackout in smart grids. This paper reviews the state-of-the-art in source identification techniques and discusses the pros and cons of current methods in this field. Furthermore, in order to gain a quantitative understanding of current methods, we provide a series of experiments and comparisons based on various environment settings. Especially, our observation reveals considerable differences in performance by employing different network topologies, various propagation schemes, and diverse propagation probabilities. We therefore reach the following points for future work. First, current methods remain far from practice as their accuracy in terms of error distance ( ${\delta}$ ) is normally larger than three in most scenarios. Second, the majority of current methods are too time consuming to quickly locate the origins of propagation. In addition, we list five open issues of current methods exposed by the analysis, from the perspectives of topology, number of sources, number of networks, temporal dynamics, and complexity and scalability. Solutions to these open issues are of great academic and practical significance.

This paper discusses the rolling blackouts implemented by the Korea Electric Power Corporation (KEPCO) on September 15, 2011, and a low-frequency oscillation that occurred at that time. On the day of the rolling blackout, spectral analysis and mode analysis were performed using the data obtained from a synchrophasor installed in the KEPCO system. Low-frequency oscillation modes near 0.68 Hz and 0.5 Hz occurring respectively before and during the process of forced load shedding were estimated. These wide-area oscillation modes may cause total blackouts, and may be good indicators of reliable system operation in the event of similar wide-area rolling blackouts in the future.

South Korea experienced a nationwide rolling blackout in 2011 due to a rapid increase in the power demand and a lack of power supply facilities. In particular, the residential sector suffered from considerable inconveniences due to power outages, such as the interruption of elevators’ operation and the stopping of all electronic appliances. Since then, ensuring a stable supply of electricity has emerged as an important task. This note aims to analyze residential consumers’ willingness to pay (WTP) to avoid power outages. For this purpose, 1000 households were surveyed, applying the contingent valuation (CV) method during May 2018. The respondents understood the CV question well and gave meaningful answers. The results show that the mean of households’ monthly WTP amounts to KRW 1522 (USD 1.41). This value is statistically significant. Converting it into an annual value and then expanding the value to the country indicate that the annual national value amounts to KRW 360.7 billion (USD 335.3 million). Since a substantial amount of investments should be made by power suppliers to prevent power outages in the residential sector, this value may be accepted as the upper limit of the benefits ensuing from those investments.

The parameters of electromechanical modes offer considerable insight into the dynamic stability properties of a power system. This paper presents a results of a LFO(low-frequency oscillation) based on the time-synchronized signals measured by synchrophasor in the rolling blackout. Spectral analysis was performed, and critical parameters were estimated using the data acquired from synchrophasors installed in the KEPCO system. As significant modes, a 0.68 Hz oscillation mode that occurred prior to the forced load shedding in the rolling blackout was estimated. Such an oscillation mode can cause an uncontrollable blackout. Therefore, the system should be operated so that significant oscillation modes are not activated. This results can serve as a reference in the future for reliable system operation in the event of a similar blackout.

Multi-concurrent failures in electric grids are severe events for modern power systems, which might result in power failures, or even rolling blackout in a large area. Usually, the possibility of such a failure in a stable system is very low, but it increases dramatically when the system suffers extreme weather. Thus the system operator needs to evaluate the risk of power systems under extreme weather conditions. This paper develops an approach to evaluate the risk of multi-concurrent failures in complicated power systems by simulating transmission line outages. A quantitative reliability index is proposed based on the probability and consequence of failures. The real large-scale power system of Guangdong Province is used for the simulation, and the result shows the effectiveness of the proposed method.

Topology errors can cause significant state estimation error or even divergence of power flow solution, which undermines the reliable operation of power grids. Undetected topology errors lead to dangerous situational unawareness in the control center; for example, an unknown transmission line outage may cause a cascading failure that leads to a rolling blackout. Existing detection methods are based on DC state estimation with residual analysis. These detection techniques use only instantaneous measurement data and require convergence of numerical solution. In this paper, a new approach that utilizes both historical and instantaneous measurement data is proposed to detect topology errors. The key idea is to track the dynamics of the power flow measurements by forecasting the measurements. Topology errors will cause the forecast measurements to be significantly different from the actual measurements. To implement this approach, a time-forward kriging-based load forecasting technique is used to forecast bus load for the next time step. The forecast load is then converted to forecast state through power flow analysis using network parameters stored at the control center. The forecast measurements can be further calculated from the forecast state. Topology errors can be detected by comparing the forecast and actual measurements. The forecast measurement errors are used as input to train Support vector machine (SVM) classifier offline. Several common SVM kernel models are compared to find the most suitable kernel for detecting topology errors. The SVM classifier can be applied in real-time to detect a topology error. The proposed approach is tested on IEEE 14 bus system with NYISO load data from Year 2011 and 2012. Our analysis shows that the proposed approach can accurately detect a single-line topology error.

We propose a method about power consumption scheduling for shaving peak load at home area using linear programming technique. Problems caused by peak load such as blackout and rolling blackout has occurred recently in the world because hourly peak load consumption is increased rapidly in the same time. So to solve these problems is using ESS. Especially, the most effective method is to utilize ESS and V2G. Electricity of the battery of parked PHEV at home area transmits through V2G to the ESS. The stored electricity in the ESS is optimized by using linear programming. This optimization reduces the hourly peak load consumption.

Manufacturing enterprises nowadays face the challenge of increasing energy price and emission reduction requirements. An approach to reduce energy cost and become environmental friendly is to incorporate energy consumption into consideration while making the scheduling plans. The research presented by this paper is set in a classical job shop circumstance, the model for the triple objectives problem that minimise total electricity cost, total electricity consumption and total tardiness when the Rolling Blackout policy is applied. A case study based on a 3*3 job shop is presented to show how scheduling plans affect electricity consumption and its related cost, and to prove the feasibility of the model.

Saitama University is located in the metropolitan area of Japan. In March 2011 on the East Japan Great Earthquake occurred. The university is about 200 km from the epicenter of the earthquake. While the earthquake did not have a direct impact on the university, it did result in multiple indirect damages. The earthquake influenced operations of the university's information infrastructure, whose system administrators had to take several operations in order to keep the infrastructure service functioning. One of the damages of the earthquake was a rolling blackout. The earthquake caused damages to various electric power plants, including Fukushima Daiichi Nuclear Power Plant. The area in and around Tokyo, the Metropolitan Area in Japan, was short of electric power, and rolling blackouts were unavoidable. Some important servers, such as web servers and e-mail, could not run because the rolling blackouts frequently caused hardware troubles. As a result, it was difficult for the people of the university to use communication tools such as e-mail, web and so on. This paper explains operational experiences and lessons based on the experiences from the viewpoint of system administrators in Saitama University; the article also discusses operation and management of information systems in disasters.

Lessons learned from the California's experience on electric power deregulation could make the transition to deregulation easier for the other states. California that had not added a major power station even with increasing demand for power due to an emerging digital technology ran short of electricity. Drought conditions throughout the Pacific Northwest had affected the available output of hydroelectric power resources and could not export electricity to California as it traditionally did. Higher emission costs, higher gas prices, under-scheduling of loads and generation, unscheduled outages, unusual weather conditions and reluctance of out-of-state generators' to deliver power affected power supply. The reserve dropped below 1.5% (stage 3) often and a rolling blackout was declared each time. California State signed long-term power contracts with companies. Since then, the wholesale electricity prices have dropped. Since January 1, 2001, about 4,300 MW of new generating capacity has been added in California. A limited price control may be the best way to handle a situation of rolling blackouts and surging wholesale electricity prices. The state should monitor power generating stations' operations and set the rules to make sure they are not being intentionally shutoff. Industry experts concluded that the problem was isolated primarily to California.

We have heard of rolling black outs as a staple of daily life in many Asian countries. We from Nepal, a country suffering rolling blackout, present a case that we refer as "Rolling blackout oral cavity". Aspiration of gastric and oral content into airway is a well known complication during endotracheal intubation but aspiration of a part of equipment during the procedure is rare. We report a case of lost bulb of laryngoscope during endotracheal intubation. Keywords: Endotracheal intubation; foreign body; laryngoscope bulb DOI: 10.3126/jcmsn.v6i3.4075Journal of College of Medical Sciences-Nepal, 2010, Vol. 6, No. 3 pp.44-45