Comparative Analysis of Reliability Performance Management of Transmission Network at Home and Abroad

With the transformation of the power system, the scale of the power grid, the structure of the power grid, the types of facilities and the management requirements have changed. The existing reliability management of the transmission network needs to be improved in terms of management methods, management scope and fields, and management techniques. This paper introduces the method and system of reliability performance management of transmission grids in China and North America, and compares and analyzes the problems existing in China's reliability management of transmission grids and the future development direction under the power reform environment. China's transmission network reliability performance management provides a reference.

0 Preface

The transmission network is an important part of the power system. Its main task is to complete the transmission of electricity, while at the same time meeting the requirements of safety and reliability. Therefore, an important indicator for measuring the performance of a transmission system is the ability of the system to complete the transmission function under the condition of random failure of the equipment. This capability not only reflects the level of system design, operation and maintenance, but also closely relates to the quality of the equipment itself. For China, a power grid that requires a large amount of energy for long-distance transmission, its transmission network performance evaluation is particularly important.

The performance evaluation of transmission grids around the world is started from the reliability management of power transmission and transformation facilities. The North American Reliability Organization (NERC) divides the reliability performance of the transmission network into two parts: the reliability performance of the transmission and transformation facilities and the reliability performance of the transmission network system. The reliability performance of the transmission network system is further decomposed into the transmission capacity and the transmission service capability. China's reliability management of transmission grids is still in the stage of facility reliability management. In 2010, State Grid Corporation integrated the transmission capacity indicators into the management of the State Grid and improved the corresponding data collection and evaluation system. With the rapid development of domestic new energy power generation and the acceleration of power reform, higher requirements are placed on the reliability of transmission grids. The attention and demand for reliability of regulatory authorities and power companies will change. How to be in a new situation Carrying out reliability management of transmission grids has become an important issue.

Domestic scholars have carried out relevant research by referring to foreign research results. The literature [1] refers to the North American transmission capacity evaluation index, combined with the characteristics of domestic power grid, and improves the reliability evaluation index system and calculation method of the national grid company's loop-based transmission system. . Reference [2] refers to the North American transmission system transmission service capability evaluation system, and proposes a connection evaluation price index that adapts to the development status of China. Literature [3] introduces the reliability performance evaluation indicators of transmission systems used in North America and the United Kingdom, and compares the differences between China and the United Kingdom and North America. The above studies are all domestic evaluation systems based on the North American evaluation system. Although they have improved slightly, they have not jumped out of the overall framework, and they have insufficient analysis of the problems and needs of the existing domestic management systems.

Based on the comprehensive investigation and analysis of the reliability performance management of transmission grids at home and abroad, this paper compares the differences between domestic and foreign management systems, puts forward the existing problems in China, and analyzes the domestic reliability management of transmission grids under the situation of power reform. The need and demonstrate the key technologies needed for future management.

1 Current status and comparison of reliability performance management of transmission networks at home and abroad

1.1? Analysis of the status quo and effectiveness of reliability management of domestic transmission grids

1.1.1? Management status

China's reliability management of transmission grids is still in the stage of facility reliability management.

1) Standard system. The "Power Transmission and Distribution Facilities Reliability Evaluation Procedures" formulated by the Electric Power Reliability Management Center in 2003 was officially issued and implemented, and was revised and improved in 2012 to guide the development of the reliability of power transmission and transformation facilities of various power grid companies. In 2010, State Grid Corporation issued the "Transmission System Reliability Evaluation Implementation (Trial Draft)", which proposed the concept of transmission system loop. In the subsequent reliability information management system, 13 types of power transmission and transformation facilities were all associated with three. In the big loop.

2) Data collection and evaluation system. After the evaluation procedures were issued, the Power Reliability Management Center established a series of reliability information management systems for power transmission and transformation facilities, which were promoted and applied nationwide. In 2009, the State Grid Corporation established a production management system (PMS) based on the existing promotion system, and realized the whole process management of facilities and production operations.

At this stage, the information system used by the State Grid Corporation combines the research results of the asset life cycle management research; through the scientific historical data analysis and mining, accurate and timely current state assessment, and achieves a forward-looking risk assessment. The information system relationship is shown in Figure 1.

Figure 1 State Grid Corporation Information System Association System

3) Evaluation system. China has established a more comprehensive facility reliability index evaluation system, which is mainly divided into two categories: time class and time class. The indicator system is a quantitative description of whether the power transmission and transformation facilities are available, and is a comprehensive measure of the various levels of planning and design, facility manufacturing, installation and commissioning, production operation, maintenance and repair, and production management.

1.1.2? Work performance

After more than 30 years of development, China's reliability management has achieved remarkable results, mainly in the following aspects:

1) Promote the improvement of the quality of facility manufacturing.

Through the analysis of national reliability statistics, the total number of unplanned outages caused by poor product quality has been declining year by year.

2) Promote the improvement of the lean level of facility operation and maintenance management.

In order to reduce the outage caused by overhaul, various grid companies have tried to carry out state maintenance, which has made the number of overhauls and workloads, maintenance trials and workloads of 110 (66) kV and above power transmission and transformation facilities decrease year by year, and the power transmission and transformation facilities The planned outage rate is declining year by year.

3) The management methods and management level of reliability indicators for power transmission and transformation are effectively improved.

Through the control of reliability indicators, the grid enterprises are promoted to improve management methods, such as scientifically arrange maintenance and maintenance, reduce the rate of repeated outages; check for potential safety hazards and defects of transmission and distribution facilities, reduce the number of failures; carry out planning, procurement, and overhaul Scheduling multiple departments to work together to improve system reliability.

1.2?Reliability performance management system and development trend of foreign transmission network

At this stage, the management systems established by countries for the reliability performance of transmission grids have certain commonalities. This paper chooses to carry out the analysis and comparison of North American regions with earlier reliability management of power transmission and transformation, better management system and significant management results.

1.2.1? Management organization and evaluation system

1) Management system. NERC manages Category 4 transmission facilities with voltage ratings greater than or equal to 200kV. As the core organization of performance management of power transmission and transformation systems in North America, NERC's main responsibilities include: formulating reliability standards for transmission and transmission systems, and supervising the enforcement of relevant enterprises; responsible for reliability assessment of transmission and transmission systems; monitoring of transmission and transmission systems Organize typical accident investigations; be responsible for training and operational personnel certification in the industry. The management system is shown in Figure 2.

Figure 2 North American Reliability Management System

2) Data collection process. The North American region divides data collection into two phases: the first phase collects only automatically reported blackout failure data, including continuous (permanent) blackout failures and transient power outages (less than 1 minute), characterizing the facility in the absence of interference from regulatory factors. The operational reliability situation in the state; the second phase collects the non-automatically reported blackout failure data, including planned outage and operation outage, and characterizes the influence of artificial control factors on the reliability of the facility, to a certain extent reflects the relevant power transmission and transformation personnel. Quality of work. The two-stage data collection, analysis, and reporting process is shown in Figure 3.

Figure 3 North American data collection, analysis, reporting process

The specific responsibilities of the responsible department in each link: TO is responsible for collecting basic data according to the requirements of the higher level; RC is responsible for data inspection, accident numbering and evaluation of multiple line blackouts caused by the same structural failure; NERC is responsible for multiple regional power reliability management centers The power failure accident is numbered, and the default data is supplemented, the reliability index is calculated, and an annual report is prepared.

3) Evaluation system. The reliability evaluation indicators used in the current stage of North America mainly reflect the frequency of instantaneous outages and continuous outages of facilities, the data distribution of facility failure time, the proportion of faulty facilities, and the operation status of parallel towers. Based on the calculations of these indicators, NERC publishes a public report each year showing each region and national level, providing data that can be used to improve reliability, and providing each transmission company with an internal report on the same specifications of the facility.

1.2.2? Development trend

At this stage, the reliability performance management of transmission grids in North America is mainly based on the evaluation of reliability indicators based on the state (province), and there are certain deficiencies. After analysis, the performance management system of power transmission and transformation systems in North America has the following development trends.

1) Decentralized management develops towards centralized management.

Large-capacity and long-distance transmission have become the main features of the contemporary power system. The system is increasingly large and complex. The traditional state (provincial)-based decentralized management model has been difficult to adapt to the current social requirements for resource allocation and power exchange.

2) Administrativeization to market development.

Compared with traditional administrative methods, market-oriented management interferes less with the internal affairs of enterprises and is completely result-oriented. Through the market to guide business decisions, both power supply reliability and economy can be considered.

3) Single indicator management develops in the direction of equal emphasis on indicators, statistical methods and statistical processes.

The power transmission and reliability evaluation index system and its statistical methods are similar and standardized, and focus on the overall evaluation of power transmission and transformation facilities and transmission network performance from the perspective of transmission systems.

4) Transmission network reliability evaluation to the development of power system reliability evaluation.

Reliability assessment tends to combine independent evaluations of power generation, transmission, and power distribution to form an overall assessment of the entire power system.

5) Reliability evaluation develops toward reliability performance risk assessment.

In 2009, NERC gradually established a data collection and statistical system based on the reliability of the transmission and transmission systems, covering both the demand side information. An event-driven, run-state-driven and standards-driven power system risk assessment system was established to conduct risk assessments of operational power systems from daily, monthly, yearly, and multi-year time scales, and to identify weak systems based on the assessment results. Point, put forward the focus of future operations and planning.

1.3? Comparative analysis at home and abroad

Since China only includes facility reliability management in terms of industry standards, this paper mainly compares and analyzes the national grid company and the North American management system. The content mainly focuses on the basic information record of the facility, the reliability index evaluation and the reliability management effectiveness. aspect.

1.3.1? Differences in facility status classification methods

The classification of facility status used in China and North America is shown in Figure 4.

Figure 4 Status classification of power transmission and transformation facilities at home and abroad

The classification of unavailable states in North America is automatically and non-automatically divided to reflect the impact of automation levels. At the same time, the automatic power outage is divided into instantaneous and continuous, reflecting the consequences of more attention to outage. China's division of available status can reflect the utilization rate of facilities to a certain extent. At the same time, the meticulous classification of the outage status, more emphasis on the reasons and time of outage, helps to identify problems in operational management. The difference in state division is inextricably linked to the purpose of management. The North American standards are based on regulation, while China is based on regulation and at the same time serves the enterprise.

1.3.2? Differences in facility reliability evaluation indicators

The reliability evaluation indicators of facilities in China and North America are divided into two categories: time and frequency. 1 For time-based indicators, North America mainly refers to indicators that describe the distribution of outage data, and China mainly focuses on the proportion of different outages in total operating time. 2 For frequency indicators, the difference between most indicators in North America and China is the same as the difference in the status of the two facilities. At the same time, the two parties also have some characteristic indicators. For example, China has established an exposure rate indicator reflecting the utilization rate of facilities. A common cause stop-off indicator that reflects the mutual influence of facilities and a fault component ratio indicator that reflects the quality of the facility itself.

1.3.3? Comparison of system reliability indicators

At present, the reliability performance evaluation of power transmission and transformation systems in North America is divided into transmission capacity and transmission service capability. The current evaluation of China State Grid Corporation is limited to transmission capacity. The evaluation of transmission capacity in North America and China is based on the reliability of the “facility group” of the loop [10]. The loops in North America are limited to transmission circuits such as cables, overhead lines, and DC lines. China includes three circuits: transmission, substation, and bus. In contrast, China's statistics are more comprehensive. There are also few differences in the state of the transmission circuit between the two parties, similar to the division of the state of the facility.

1.3.4? Differences in the classification of facility failure causes

The fault cause classification setting is the basis of fault analysis. North American NERC divides 12 major types of faults according to the proportion of faults, including weather, lightning, environmental factors, pollution, external factors, fire, vandalism, etc., which are relatively simple and practical. . China divides the cause of the failure into responsibility reasons and technical reasons. The reasons for the failure are all covered. The reasons for responsibility are divided into 10 categories, including 93 explosions, improper command, misuse of materials, and loose sealing. Technical reasons are divided into 8 categories, including 137 items such as fracture, single-phase short circuit and oil leakage. Compared with foreign countries, the classification of China's outages is relatively complicated.

1.3.5? Comparative analysis of facility reliability levels at the present stage

Due to the management differences between the two parties, the availability of the lines and transformers with the same two-way evaluation method in 2010–2014 was selected as the comparison target of the reliability level. At the same time, based on the difference between the causes of the two parties, the actual facility failures of the two parties based on the operational data.

Because of the comparative analysis.

1) Comparison and analysis of the availability of power transmission and transformation facilities.

The variation of the availability of the two lines and transformers in the comparison range is shown in Fig. 5.

Figure 5 Two-way line and transformer availability

Obviously, the availability of China's power transmission and transformation facilities is significantly higher than that of North America. The average availability of AC lines is about 1% higher, and the average availability of transformers is 2.6 percentage points higher. Through the calculation of the ratio of the planned outage time to the unplanned outage time of the facility, an in-depth analysis of the availability management level of the two power transmission and transformation facilities is shown in Tables 1 and 2.

It can be seen from Table 1 and Table 2 that the ratio of planned outage time to unplanned outage time in North America is significantly better than that in China. The transformer time ratio in 2011 is even close to 100 times. This shows that the management of the power transmission and transformation facilities planned maintenance program in North America is significantly better than China.

2) Comparison of the causes of failures in power transmission and transformation facilities.

The number of causes of power transmission and transformation facilities failures in NERC statistics for 2012–2014 indicates that weather factors, misoperations, AC lines and substation facility failures accounted for 55.21% of all failure causes, while there were 20.79% outages. The cause of the incident is unknown. In the same statistical years, the main causes of failure in China were climatic factors, natural disasters, external damage and poor product quality. Unplanned outages caused by four types of causes accounted for 78.75% of the total number of outages, while China had 6.48%. The reasons for the unplanned outage incident are unknown.

2 Analysis of problems in reliability performance management of China's transmission network

Based on the comparison of the above-mentioned domestic and international transmission network reliability performance management and the investigation of China's actual management work, it is concluded that China's management methods, data records, data mining and management economics have the following aspects.

2.1? Management system leads to insufficient supervision

The functional positioning of China's power transmission and transformation reliability supervision department focuses on the service power system, and the supervision of the power system is weak. In the reliability management, the power enterprise completed the whole process of data collection and reporting, and lacked the supervision of intermediate links, which led to the questioning of the authenticity of important information such as the cause of the failure and the time of failure, which caused the reliability management to lose its basic support.

2.2? Management objectives do not correspond to management functions

Reliability management can be divided into two major aspects: supervision and enterprise. Each level forms a closed-loop management to truly improve reliability. To improve reliability at the regulatory level and to establish national reliability standards, it is necessary to grasp the overall situation of load, system operation and reliability. However, China's current reliability supervision functions and information are too singular; On the basis of sexual standards, we strive to operate economically. Therefore, enterprises should integrate reliability statistics, equipment maintenance, overhaul, planning, etc. into the life cycle management of equipment. At present, they are more focused on statistics and serve supervision, but they ignore the internal management objectives.

2.3? Technical reasons for failure and responsibility reasons need to be improved

1) Reasons for power transmission and transformation technology.

According to the statistics of 2010–2014, the proportions of technical reasons for the operation of power transmission and transformation facilities are “others”, which are 51.5%, 35.7%, 34.1%, 36.8% and 49.2%, respectively. The filling ratio is extremely high, which affects the fault. An in-depth analysis of the cause.

2) Reasons for the responsibility of power transmission and transformation.

Combined with the historical operation data of the national power transmission and transformation facilities in 2011–2014, the statistical analysis shows the main responsibility reasons for each year as shown in Figure 6.

Figure 6 Distribution of responsibility reasons in unplanned outages from 2010 to 2014

According to Figure 6, the proportion of unplanned outages in China's power transmission and transformation facilities is relatively low, especially due to improper dispatch, improper leadership, and fuel impact during the statistical period.

On the one hand, the above analysis shows that there are unreasonable factors in China's setting reasons for liability reasons and technical reasons. On the other hand, it also indicates that the reliability input personnel are not serious about filling in the data records.

2.4? Data accuracy, standardization and integrity need to be improved

At present, all domestic units pay more attention to the reporting of reliability data of overhead lines, transformers, circuit breakers and disconnectors, which are included in the benchmarking statistics, but the data attention of other facilities is insufficient. At the same time, there are also phenomena in the data entry personnel who do not understand the procedures, the system is not skilled, and deliberately change the data. The above reasons have greatly affected the accuracy, standardization and integrity of the reliability performance data of the transmission network.

2.5? Reliability indicators do not reflect the difference in reliability

The reliability index statistics do not consider the impact of special terrain and special environment on reliability data, resulting in limited application of indicators. For example, the reliability indicators of typhoon-prone areas are greatly affected by typhoons, while the inland areas are not affected by typhoons. The impact of typhoon on reliability is included in the calculation of indicators, which does not really reflect the difference in reliability management levels in different regions.

2.6? Insufficient data depth analysis

Although China has accumulated a large number of transmission network reliability operation data, due to insufficient depth analysis, the data cannot provide support for some actual work. The reliability data of transmission grids have not fully exerted their effects on improving the quality of power facilities manufacturing, the quality of engineering construction, and improving the reliability level of power grid enterprises.

2.7? The application of reliability and economy is far from being realized.

In the various stages of power grid enterprise power transmission and transformation facilities management, the reliability of power transmission and transformation facilities can be improved by improving the manufacturing quality and installation quality of the facilities, strict facility selection, maintenance, and production operations, but reliability cannot be achieved. Cost fine accounting. Power grid enterprises pay more attention to the reliability of power transmission and transformation facilities, and lack of attention to economics, resulting in grid companies far from achieving a balance between reliability and economy in asset management.

2.8? Transmission and transformation reliability management information system needs to be improved

At present, the power reliability management center uses a system with the power enterprise. The system mainly meets the requirements of the indicator statistics of the power reliability management center. Because the basic data of the system is not complete enough and the data mining degree is insufficient, it leads to the internal reliability of the enterprise. Satisfaction with sexual data and economic needs is poor.

3 China's transmission network reliability performance management development direction

3.1? The impact of power reform

From the perspective of supervision: the whole society has higher and higher requirements for power system reliability [13]; meanwhile, with the launch of comprehensive power market reform, the lack of power reliability management increases the risk of reform. From the perspective of enterprises, the reform of power marketization has intensified the impact of cost control on the sound development of enterprises. Power companies are asset-intensive enterprises, and the reduction in asset utilization forces power companies to conduct asset management. One of the important parts of asset management is equipment reliability management. Therefore, the reliability management of transmission grid not only meets regulatory requirements, but also meets the internal management needs of enterprises.

3.2? Analysis of the needs of enterprise asset management

In 2008, China's power companies, in combination with their own characteristics and advanced foreign management experience, gradually carried out the work of asset life cycle management. At present, the life cycle of assets of domestic power companies is mainly based on power facilities [13]. The essence of carrying out asset life cycle management is to reduce the life cycle cost of the facility as much as possible on the basis of ensuring the operational reliability of the facility [14]. Therefore, the reliability performance management of the transmission network is also the demand of enterprise asset management.

3.3? Key issues for future improvement

In view of the current status of domestic reliability management and the drive for future reforms, several key issues that require urgent improvement are proposed:

1) How does China's reliability supervision function ensure the authenticity of reliability data: strengthen the tracking and supervision of accidents through the adjustment of management functions and management processes, or guarantee through reliability legislation.

2) Coordination of management content and objectives at the two levels of supervision and management: China is currently trying to achieve real-time reliability supervision of full voltage levels and full facilities, increasing management difficulty and management costs. In accordance with the guiding ideology of comprehensive supervision, focus, and control cycle, improve the types of management equipment and reporting cycles, and pursue effective management. Enterprises shall carry out full asset management of reactive equipment, secondary equipment and communication information equipment according to the needs of the whole life cycle. Enterprise systems can generate regulatory center data for incremental incremental data updates.

3) The supervision department perfects the evaluation system: Combining the characteristics of China's own power grid, it gradually carries out the evaluation of transmission capacity, transmission service capability and power system reliability, and thoroughly studies the integrity of the indicator system and the directivity, measurability and consistency of each indicator. And gradually establish a risk assessment system.

4) Closed-loop management of reliability of power enterprises: Firstly, establish an information support system for enterprise life-cycle asset management, start from the bidding of equipment and enter the management file. The equipment management runs through various operation processes such as repair, overhaul and failure, and realizes and finances. Correlation of data, etc.; then carry out in-depth mining of fault information of transmission network equipment, and provide necessary data for enterprise life cycle management; finally, the reliability improvement means is proposed through analysis.

4 Conclusion

This paper analyzes the current status of China's transmission network reliability performance management and compares it with the advanced management experience in North America, and obtains the difference and effect analysis of reliability performance management of transmission grids at home and abroad. Finally, the power reform and the needs of enterprise life cycle management are considered. The development direction of future power transmission and reliability performance is analyzed, which provides reference for the adjustment and optimization of future management system.

Others Etching Products

We custom Etching Cutting Die, Etching Metal Crafts, Etching Eyeglass Frames, Etching Plate Heat Exchanger Sheet with drawings provided by customers. We are equipped with professional metal etching equipment and exposure development equipment. The raw material we more use for these products is stainless-steel, brass, titanium and titanium-palladium. We can guarantee that our half etching plate heat exchanger sheet have straight surface line, and have no burr, high product accuracy.

Etching Cutting Die,Etching Metal Crafts,Etching Eyeglass Frames,Etching Plate Heat Exchanger Sheet

SHAOXING HUALI ELECTRONICS CO., LTD. , https://www.cnsxhuali.com