Read and explain in your own words what you understand about this discussion? Literature Review Continuous supply of electrical power is vital to the sustainability of the country. When a power system failure or blackout occurs, the consequences can be far-reaching.
Some of the most significant causes leading to power system blackouts and failures are the result of transmission lines tripping or overloading. In some instances, the cause is due to failure of control and protection systems, operation, equipment being struck by lightning, equipment failure, poor maintenance and human error, voltage collapse, cyber-attacks, quick-frequency declines, and others (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). Since 2010, several documented power systems blackouts have occurred, leaving millions of customers and businesses in the dark.
For instance, on September 8, 2011, a power outage occurred in the Pacific Southwest lasting 12 hours and affected 2.7 million residents in San Diego, California, Arizona, and Mexico (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). According to Alhelou, Hamedani-Golshan, Njenda, & Siano (2018), a tripped transmission line during peak usage caused a system overload leading to grid failure causing a complete blackout for the city of San Diego.
In the same year, in February 2011, Brazil experienced a 16-hour blackout due to flaws in the transmission lines that impacted 53 million customers. July 2012, a 15-hour blackout occurred in India, affecting nearly 620 million residents (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). This blackout was due to overloading one of the 400 kV Gwali–Binar transmission lines while maintenance was being performed on the primary transmission line (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018).
The following day another system failure occurred due to demand-generation imbalance and impacting 700 million people (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). United States Occurrences Historically, the United States has seen an increase in the number of blackouts occurring nationwide.
Figure 1 demonstrates blackouts in the United States between 2008-2015, as documented in the literature authored by Alhelou, Hamedani-Golshan, Njenda, & Siano (2018). Figure 1 United Stated Recorded Blackouts Year Total Number of Outages People Affected (millions) 2008 2169 2009 2840 2010 3149 2011 3071 2012 2808 2013 3236 2014 3634 2015 3571 According to the literature, of the 3571 outages recorded in 2015, the following top ten states had the highest recorded outages (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018).
California was documented to have the most outages, with the most people affected, with 417 outages recorded, accounting for approximately 25% of the recorded outages (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). On record, Indiana experienced the least number of recorded outages accounting for 100 power outages in the same year (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018).
The primary reason for these outages was said to be weather conditions. Consequently, the indicated outages in areas with the highest number of outages experienced more unusual weather conditions. Figure 2 (There is a pie graph here that will not copy and paste into this discussion post) Global blackouts United States-Canadian Grid The most severe major blackout in the grid was the blackout in August 2003.
The outages left 50 million people without power in eight states in the US and two Canadian provinces. According to Alhelou, Hamedani-Golshan, Njenda, & Siano (2018), reports published, more than 400 transmission lines and 531 generating units at 261 power plants tripped.
Before the blackouts occurred, the system was evaluated and reported to be operating according to the North American Electric Reliability Council (NERC) standards. Nonetheless, reactive power supply challenges have been previously documented. Another issue was the faulty operating of a Midwest ISO (MISO) state estimator and the real-time contingency analysis (RTCA) software. Real-time system information was delayed and compromised due to software issues.
Northern Ohio experienced an outage of the Eastlake Unit 5 generator due to the system operating under-stressed, reactive power conditions (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018).
The units produced high reactive power outputs, which led to the tripping of the voltage regulator to manual system regulator due to over-excitation. Operators worked tirelessly to intervene by restoring the voltage regulator to automatic, but the unit tripped. The result was a cascading failure of the power grid leading to the most significant blackout recorded. According to Alhelou, Hamedani-Golshan, Njenda, & Siano (2018), three 345kV transmission lines were also tripped after a tree crippled the lines, making the situation worse. Continuous cascading failures occurred when many 345kV lines overloaded due to the systems being under-voltage and unable to handle the carryover. Additionally, out-of-step oscillations resulted, and the system split into several islands, leading to a severe blackout.
The task force on power outage concludes that the primary cause of this blackout was inadequate understanding of the system and lack of situational awareness. Poor vegetation maintenance and lack of support from the reliability coordinator presented additional challenges. Swedish-Danish Blackouts The Swedish-Danish system blackout occurred that same year on September 23, 2003.
The system was reported to be operating under normal conditions. Still, some system components involving the 400 kV transmission lines and the HVDC links connected to this system with continental Europe were out of service on maintenance (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). The system was not believed to be heavily loaded. Despite this, the initial failure began when the 1200 megawatt nuclear unit in southern Sweden tripped, triggering issues with a steam valve (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). The system was operating normally, but a chain reaction of failures occurred.
Moments later, a double bus bar fault occurred at one of the substations causing lines to be lost and units began to trip (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). A 400kV transmission line was the only one left that was responsible for transferring power from north to south. This line eventually failed under the heavy load causing a system separation and voltage collapse.
Nearly a million customers were affected when the south of Sweden and the east of Denmark were separated. Switzerland and Italy On the same date that the Sweden-Denmark collapse occurred, September 23, 2003, an additional blackout occurred in Italy due to a tree causing a flashover resulting in the tripping of a significant tie-line between Italy and Switzerland. Cascading failures began to progress when an automatic breaker failed to reclose the line leading to failed synchronization.
According to Alhelou, Hamedani-Golshan, Njenda, & Siano (2018), the 380kV Lukmanier line tripping was initially recorded at 03:01:20. About 25 minutes later, another 380kV San Bernadino transmission line was interrupted after delays in power re-dispatching. The Italian system lost synchronism with Europe, and sixteen transmission lines were tripped in Italy due to systems overloading and compounding instabilities.
With the continuous system separation, the Italian power system was left with a deficit that it was unable to compensate for. The system frequency began to falter, and operators could not correct the situation in time, thus causing the Italian power system failure. India Blackouts The greatest blackout in terms of lost power and the number of people affected occurred in India in 2012.
India is the third-largest power-producing country after China and the USA, with a yearly production of 1423 TWh (TeraWatt hours). In 2012, the Indian grid experienced its worst blackout. India’s extreme weather conditions in the summer of 2012 led to unusually high demands for power for cooling systems.
Due to limited water supplies, the hydropower plants were generating below their full capacity. On July 30, 2012, around 2:00 ., a 400kV Gwalior–Binar circuit breaker tripped, triggering a series of events, which later led to a system collapse (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018).
The area was affected when the primary power stations experienced a 32 GW loss in power generation (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). Three hundred million customers lost power, and cascading infrastructure failures occurred.
This caused the airports, passenger trains, and railroads, and traffic signals to shut down, leading to confusion and congestion in the business districts. (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018).
Hospitals endured three to five hours of power loss with no reliable power backup supplies. After nearly 15 hours, 80% of the power was restored. The next day on July 31, 2012, another power disturbance occurred at around 1:02 .
A relay problem near the TajMahal and several power stations were again grounded, leaving another 600 million people without power (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). Again, another infrastructure failure cripples critical facilities in the transportation sector, such as the metro rail and railway systems, multi-story building lifts and elevators, and traffic signals are rendered inoperable.
Some miners were trapped underground and later rescued. Traveling metro passengers had to be rescued as well. Later, an investigation was conducted investigating these disturbances. The investigation revealed a weak power transmission line was the culprit of the first outage. The second was due to a failure to respond to the dispatch centers, which led to a management failure of the power flow, causing the lines to trip (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018).
Brazilian Grid Blackout Although it is not very common, power outages are continuing to be witnessed across the globe. The main challenge with power outages and blackouts is that they lead to heavy economic losses (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). On March 21, 2018, more than 10 million customers were affected when a power outage struck the Brazilian power system.
The power outage started at 3:40 . due to a transmission line failure near the Belo Monte hydropower station (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). About 18,000 megawatts (MW) of power was restricted during this disturbance. Hydro generators mainly supply the Brazilian power system demand and have been studied for years.
The first special protection scheme (SPS) was implanted in Brazil in 1974, and it was a three-stage under-frequency load-shedding scheme (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). In 1975, only five SPS were in operation and, by the year 2005, they had increased to 133 (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). It was proven that the SPS system being utilized in Brazil was rated superior in mitigating the effects of blackouts from the various systems that were analyzed in contingency situations (Alhelou, Hamedani-Golshan, Njenda, & Siano, 2018). An upgrade from n-1 to n-2 contingency was also proposed to enhance power systems reliability during disturbances (Ahmad, Khan, Khan, Khan, Tareen, & Saeed, 2018). On November 10, 2009, and February 4, 2011, other blackouts in Brazil also lead to recommendations on enhancing the system against significant disturbances and improving the black-start restoration capabilities (Ahmad, Khan, Khan, Khan, Tareen, & Saeed, 2018).
In modern systems, proper maximization of wide-area measurement systems can go a long way in improving system reliability (Ahmad, Khan, Khan, Khan, Tareen, & Saeed, 2018). Causes around the Globe According to Alhelou, Hamedani-Golshan, Njenda, & Siano (2018), there have been significant power outages worldwide from 2011 to 2018.
These occurrences have been comprehensively documented and reviewed. Figure 3 gives a brief overview of significant blackouts and cascading events over the last decade. Additionally, the duration of each blackout is provided.
It can be seen that the blackout that occurred in Bangladesh on November 1, 2014, has the highest duration of 24 hours. The Indian blackout on July 30, 2012, impacted the highest number of people at 620 million affected. The majority of causes of the blackouts are related to transmission system operation, control, and protection.
Other helpful information about the significant blackouts in this decade is given in the table below. Figure 3-Summary of recorded major power outages around the globe in this decade. (there is a chart that will not copy and paste into this discussion post) Research Theories Theories inform the field of emergency management and aids in the development of policies and procedures.
Self-organization theory is one of the representative achievements in the research of complex system theory in recent years (Wang, 2019). Self-organization theory holds that the chain reaction caused by small events can affect any number of components in the system in the critical state, and the chain reaction in all scales is the constitution of its dynamic characteristics (Wang, 2019).
A series of minor uniform disturbances will make the system take place the “avalanche” events large and small in the macroscopic performance. Using the complex system theory, American scholars Dobson and Cameras analyzed the blackouts in the American power system from 1984 to 1999 (Wang, 2019). According to Wang (20198), the scholars utilized the sandpile model to demonstrate the self-organized critical state intuitively.
Wang (2019) explained it in terms of a pile of sand being piled up on a platform by adding sand at random, one grain at a time. With the increase of the sandpile, its slope gradually increases. Once the slope between the adjacent positions of the sandpile reaches a specific closed value, a collapse will occur (Wang, 2019). If the increase of the power load is similar to the falling sand in the sandpile model, when the load increases to a certain level, the power system will enter the critical state, just as the sand grains will slide when the slope of the sandpile is too steep.
Caused by the size of the avalanche, the critical state of the power system is bound to occur in varying sizes of blackouts. The self-organized criticality of the power grid can be further explained in the following ways: the increase of load will lead to the decrease of the system operating margin and the increase of the probability of accidents; On the other hand, people continue to maintain the power grid, building new power plants and transmission lines, to improve the load capacity of the entire grid and reduce the probability of accidents.
These two opposing forces will eventually reach a state of equilibrium, which is the dominant self-organization process of power network evolution. Historical Measures and Policies for Addressing Problems To prevent and deal with cascading failures, it is necessary to understand the occurrence and development process of cascading failures and the main factors to promote the transmission of cascading failures.
The research shows that the cascading failure in the large power grid from the initial event to the failure’s cascading end of the blackout will take a long time. In the process, the chain reaction speed will pick up gradually.
The interval between failures will be reduced from the first minute to the second and eventually after a critical failure. The system loses many components in a very short period of time, and the system blackout occurs (Peizheng, 2015). A typical power grid cascading failure, including the start, development, climax, and collapse of the four phases.
The analysis of previous large-scale cascading faults at domestic and overseas grids evidence that the primary factors promoting the fault propagation in the development stage of cascading failures include large-scale power flow transfer, inappropriate action of protection, and insufficient reactive power support of the receiving end power network (Peizheng, 2015).
Given the above analysis, combined with the common problems of blackout at domestic and overseas, the following prevention and emergency measures have previously been taken to combat power grid cascading failures: Increase the construction and investment of electric power to avoid the problem of shortage of electric power supply. In recent years, the deep-seated causes of blackouts worldwide are often caused by such factors as overload, the balance of power flow distribution, etc. (Peizheng, 2015).
Reasonable planning of power network and setting of relay protection. Only by ensuring a strong grid framework, complete and accurate relay protection can risk be avoided to the maximum extent (Peizheng, 2015).
Adhere to the unified scheduling mechanism. The lack of coordination capacity, machine network, transmission, and distribution network coordination often lead to small accidents that cannot be dealt with in time but expand the scope of the accident, resulting in severe consequences (Peizheng, 2015). Strengthen the research of basic technology and the training of operators. Cascading fault is a dynamic development process in the blackout accident. As long as the operator finds out the problem in time and takes the correct emergency measures, the accident’s further deterioration can be effectively controlled (Peizheng, 2015).
References Alhelou, H., Hamedani-Golshan, M., Njenda, T., and Siano, P. (2018). A survey on power system blackout and cascading events: Research motivations and challenges. :///C:/Users/annod/AppData/Local/Temp/ Ahmad, I., Khan, F., Khan, S., Khan, A., Tareen, ., and Saeed, M. (2018). Blackout Avoidance through IntelligentLoad Shedding in Modern Electrical Power Utility . Appl. Emerg. ,8, 48–57. Peizheng, L. (2015). Power System Cascading Failure Model and Self-organizing Criticality Identification Method Based on Complex System Theory. Chongqing University. Wang, J. (2019). Power grid cascading failure blackouts analysis. AIP Conference Proceedings 2066, 020046.
