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International Journal of Management Science and Engineering Research Volume 3 Issue 1, 2016 doi: 10.14355/ijmser.2016.0301.03
Research on Power Grid Engineering Risks Assessment Based on AHP under EPC Mode Xin Liu*1, Shunzhi Zhu2 Electrical Engineering School, Wuhan University, Wuhan 430072, Hubei Province, China
1
Economics and Management School, Wuhan University, Wuhan 430072, Hubei Province, China
2
840906794@qq.com; 2Shunzhizhu@163.com
*1
Abstract This paper analyses and summarizes papers about engineering projects in the domestic and foreign EPC mode, and researches the risk management of power grid project based on AHP under EPC mode. Firstly, the paper describes the application and research of EPC mode in China's electric power engineering, and analyses the existing risk management under EPC mode. Secondly, this paper expounds the basic theory of risk management, and puts forward the principle and standard of risk assessment, and defines the basic process and method of risk management. Thirdly, it introduces the analytic hierarchy process in this paper. At last, according to the process and characteristics of power grid construction in EPC mode and the use of risk identification and assessment theory, the paper empirically tests the application of risk management under EPC mode in Leshan substation engineering through the AHP. Keywords Analytic Hierarchy Process; Power Grid Engineering; EPC; Risk Assessment
Introduction In the international general contracting market, EPC general contracting model is favored for its ability to transfer engineering construction risk, save investment and give full play to the leading role of design. It is gradually applied to large scale projects in various industries. The implementation of EPC in power grid project increases the controllable initiative of the general contractor, achieves the design, procurement, construction of internal coordination, mitigates the contradiction between the parties, and reduces the cost of coordination of the EPC general contractor, which is conducive to the overall progress of the general contractor's risk management. Therefore, EPC will become the mainstream mode of power grid project contracting. However, at present, the research on risk evaluation of power network based on EPC mode is less. Because of the successful application of EPC mode in all kinds of projects in China, experts and scholars realized that it will be used in the trend of power grid project, and strengthening the research on risk assessment of power grid project with EPC mode will give a technological favor to risk analysis. Some scholars pointed out that EPC can well solve some problems arise from China's power shortage and the limitation of power investment funds, elaborated problems should be noticed with the use of EPC model in wind farm projects from the owner's point of view, and on the basis built a set of risk assessment models. This paper stands at the owner's point of view, and the results will be very different from the perspective of the general contractor. There were also scholars who used evaluation method combined entropy method and sequencing method to analyze the risk factors that the domestic associated total contractors based on EPC mode may face, but the method cannot be completely copied in the power grid project. Some scholars have put forward the measures to reduce the risks of the general contractor based on EPC mode’s connotation and advantages, and summarized the risks of the project. But the proposed solution is relatively simple and there is no scientific risk evaluation method as a support. On this basis, this paper adopts the AHP method, analyses and evaluates the risk of power grid project based on EPC mode, and provides methods and ideas on how to evaluate the risk of EPC project. Risk Assessment Principles The extent of the risk cannot be reflected by the simple qualitative analysis, which is easy for the manager to ignore
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the risk management focuses. And simple quantitative analysis is not practical, because it does not fully draw on the experience of management and field staff, and makes the analysis process become very complex. Therefore, the most appropriate risk assessment of power grid project is the use of a comprehensive evaluation method, that is, to combine qualitative assessment and quantitative evaluation. In general, the risk assessment of business processes should follow the following four principles: (1) The overall principle Risk is often caused by many aspects, such as, we must consider the various aspects of the loss, the various factors that affect the loss, and the mutual connection and interaction between these factors, when make the risk assessment.. (2) The principle of unity Risk assessment is to be targeted at a specific risk event or a specific risk of the project, and then the risk assessment should maintain unity. Don’t take into account the risk factors that have nothing to do with the risk or regard these factors as a basis for risk assessment. (3) Objectivity principle Risk assessment has a variety of methods. According to different standards and different risk assessment methods, there are different results. Therefore, the risk assessment should reflect the objective existence of all kinds of risks as far as possible. If the risk assessment’s deviation is too large, it will cause unnecessary losses. (4) Operational principles Risk assessment involves a wide range and many management difficulties. Therefore, risk management personnel should flexibly use the risk assessment method with versatility and operability and try to avoid using cumbersome or advanced assessment method as far as possible. Risk Evaluation Criteria Division of risk loss should not be too detailed, and generally the levels of risk loss are divided into five grades: very serious, severe, moderate, acceptable and ignorable. As shown in table 1. TABLE 1 DIVISION OF RISK LOSS
Risk Level
very serious
severe
Influence of Loss the influence of loss beyond the expected range of regulation, impeding the construction and the implementation of the project, bringing large loss to related persons. the influence of loss not beyond the expected regulation, severely impeding the implementation of the project, need to adjust the construction of the project by great efforts.
moderate
the influence of loss in the expected regulatory range, in the project construction plan itself can bear and digest.
acceptable
the influence of loss is less, need to adjust the construction of the project slightly.
ignorable
the influence of loss is very little, the construction project tasks do not need to be adjusted, but need to closely monitor.
For the risk level ‘very serious’, the general contractor should take some strategies to avoid the risks, which make enterprise avoid the big loss of the risks; for the risk level ‘severe’, the general contractor should take some strategies to transfer the risks and take the risks with other unities or subcontractors; for the risk level ‘moderate’ which can be handled in the project, the general contractor only needs to take strategy mitigating the loss of the risks, so that the general contractor can obtain more benefits; for the risk levels ‘acceptable’ and ‘ignorable’, the general contractor only needs to take strategy accepting the risks, so there is not much work to be done.
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Risk Assessment Process Risk assessment process of the project must be systematic, continuous and operational, which generally can be divided into four partsďźš (1) Collecting relevant information needed in the risk assessment. Because the level of data quality level will seriously affect the risk evaluation results, the collected data must be accurate, real-time and objective. (2) Defining the criterion of the project risk assessment. In order to analyze uncertainty risks of the project subject, the criterion of risk level needs to be required firstly. Whether a single risk or the overall risk, it is necessary to establish the criterion of risk, in order to enhance the reliability of the results of risk assessment. (3) Establishing the risk assessment model and estimating the risk level of the project. According to the selection principle of evaluation method, select the appropriate qualitative and quantitative method, then establish the risk evaluation model, and analyze the internal relationship between the risk factors, and determine the risk level of the project. (4) A comparative analysis of risk levels and criterion. Compare the single and overall risk level of the project with the criterion of the determined risk assessment, so as to determine whether the risk level of the project can be accepted, and provide the basis for the project's investment decision. AHP Assessment Method Hierarchy Process Analytic (AHP) is a multi-criteria decision-making method which is a combination of qualitative analysis and quantitative analysis. AHP method can quantify the process of complex system which humans think about. It also can quantify the analysis of human's subjective judgment and the differences between factors and make the thinking process coincided. Its basic idea: when solving the multi-criteria decision making problems, remove it into a series of factors. Based on their affiliation, form the hierarchy structure which can reflect the relationship between factors, therefore, it becomes a problem to determine the importance weight of the objects to be evaluated. Therefore, the problem of the comprehensive evaluation can be transformed into the problem of determining the order of the objects to be evaluated. The steps of AHP assessment method are as follows: (1) The set of indicators is hypothesized as (1) According to the results of the evaluation of the experts, the whole indicators are re-sorted, and then the new set of indicators after being re-sorted is , . (2) Calculate the importance ratio between adjacent indicators (2) (3) The weight of the m indicators is (3) After getting the weight of the m indicators, the weight of the remaining indicators is
(4)
The whole weight is (5)
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Empirical Research on Risk Assessment based on Analytic Hierarchy Process District Wutongqiao, Leshan, is located in the southwest of Sichuan Basin. To the east, south, west and north are Jingyan County, Jianwei County, Sandy Bay and Central District of Leshan City. It is about 26 kilometers across south and north, east and west. It has an area of 474 square kilometers and a population of 330 000. In this area, transportation which includes land and water is very convenient. State Road 213 and Min River run through the territory. It has a mild climate and abundant rainfall. The main natural resources in the region are salt, coal, etc. Many chemical companies gathered there. It is famous for producing caustic soda, salt, brine, coal, electrical and mechanical products. Traditional chemical industries such as salt-making, soda-making have a considerable foundation; other industries like mechanic and electric, textile, coal also have a certain foundation. In order to meet the needs of rapid economy development, Wutongqiao District, Leshan City and improve the grid structure in Leshan City, Leshan Electric Power Bureau built a new 220kV Qiaogou power transmission project. The project commenced in March 2006 and had built part of the operation of 220kV in September 2007. 1# main transformer was put into operation in September 2007 and 2# main transformer and the corresponding supporting engineering were put into operation in December 2007. The substation is located in Group 3 of Traffic Team 2, Dam Village Laolong, Town Qiaogou, District Wutongqiao, the new contents are as follows: (1) The main transformer: 2 150MVA, three coil, 220kV/110kV/10kV, regulating transformer loaded voltage. This period is 1 150MVA. (2) 220kV adopts double busbar connection, newly-building side switches, bus connection switches, I, II busbar connection of the main transformer 220kV. (3) 110kV adopts double busbar connection, newly-building side switches, bus connection switches, I, II busbar connection of the main transformer 110kV. (4) 10kV uses a single bus segment wiring, newly-building side switches and reactive power compensation devices the main transformer 10kV. (5) Building communications, automation, protection and other secondary equipments. Risk events and risk factors influence construction period safety of Leshan power transmission project are numerous, which involve the whole process from structure design to construction. Their relationship is complicated and they have different influence on the safety of the structure. At the same time, due to the lack of construction risk accident statistics of Leshan power transmission project, it is very difficult to do the risk identification. Therefore, this article uses AHP to study the risk identification of Leshan power transmission project construction. According to the actual situation of Leshan power transmission construction projects, combination with ‘the Safety Risk Management System Implementation Guidance of the State Grid Corporation’ and ‘the Dangerous Source Identification Manual’ compiled by Leshan Electric Power Bureau, and construction experiences of the past power transmission projects, this article has analyzed the risk factors of Leshan power transmission construction project. Natural Environmental Risks The site of Lao long Dam transformer substation is located in Group 3 of Traffic Team 2, Dam Village Laolong on the east bank of Min River, Town Qiaogou, District Wutongqiao, between Town Jinsu and Town Wutong, and is nearby Town Jinsu and 10km from Town Wutong. State Road 213 is in its southwest. A disused kiln located in the site. It is nearby Gaobazi, Zhugen and other 110kV substations and many 35kV substations. The Wutongqiao power plant of Huadian Group whose installed capacity 2 50MW is 2km away from the site. Gongxiang I, II copper tower double circuits run through the southeast side of the site. The site of Lao long Dam transformer substation is about 1km far away from Gongxiang I, II double circuits and 220kV power line is so short to save investment. The site is on the middle of the flat in shallow hill, flat and open, which can arrange the outline easily. There is no flood. So the natural environment risk is less.
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Technical Risks (1) Broking rod: broking rod is caused by the improper construction method, not pulling the reverse wind rope and overexerting when shrink the lines; (2) Strand breakage and wire breakage during stretching the conductors: mainly caused by improper construction method and too tight shrinking lines; (3) Fender brackets’ dumping fender ropes’ being off: it is required to set up fender brackets when put the line across the highway, expressway and railway, etc, according to the provisions, but the unstable fender brackets during setting up, may cause the fender brackets dumped during the construction, and impede the traffic. Management Risks When putting lines across rivers, roads, railways, etc., it is necessarily to inform the relevant departments and units in advance for applying communication. The project should commence after the coincidence of communication with relevant departments and units, which requires good organization and management. However, the construction usually begins without the communication with the relevant departments and units, which results in shipping and traffic disruption and other social events. In addition, the construction of the substation involves in the procurement of materials, the coordination of technical personnel, supervision of project progress and the reasonable allocation of resources and other aspects. Based on this, the improper management may cause delays, spending beyond budget, etc. Economic Risks The project commenced in March 2006, completed and was put into operation until September 2007, which lasted a year and a half. The national economy developed rapidly. So, the price level had rose. Based on this, we need to consider the risks of the rise in prices of construction materials and labor markets which may exist during the construction of the project. Liability Risks (1) High-altitude falling: during the construction of the substation, there are a lot of essential high altitude construction work, including: building towers, erecting rods, putting wires, hanging bus wires, shrinking lines, installing equipment, etc. In accordance with the provisions of the safety regulations, high altitude operations must tie a safety belt. Shifting on the high altitude tower also needs to tie the safety rope to achieve double insurance. But in actual construction process, there are often some unsafe factors, such as seat belt’s being tied unsafely, safety belt or safety rope breaking, not taking the double insurance when shifting on high altitude, falling down when climbing tower and so on. (2) Object hit: first, accident of being injured by objects during the substation construction process; second, during the installation of current transformer and voltage transformer devices whose gravities are high, it is easy to injure person by dumping because of the soft soil; third, tower collapse caused wounding accident, when the foundation is not tamped or the wind rope is not solid during the process of erecting rods. (3) The pit foundation collapse: when excavate the foundation of the line, in accordance with the provisions should be according to the soft soil conditions put slope excavation it is not allowed to dig down vertically, also not allowed to dig the foundation whose upside is big and downside is small. In practical works, some construction personnel reduces things which make the step-slope not enough to reduce the amount of excavation, which results in the pit wall collapse during the process of excavation process and after the excavation, and causes the personnel casualty. (4) Electric shock injury: during the process of constructing the transmission line, it is often needed to across over or nearby the charged transmission line. In order to ensure the safety, the transmission line will apply for a temporary power outage in general. But if there is no careful investigation of the scene and the power transmission line applied originally has not been stopped, it will be very likely to get electric shock and the occurrence of security incidents during the construction process.
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(5) The fly line wounding: when using an electric winch reel, it is possible to cause the conductor fly line wounding, because the steering pulley is not firmly fixed. Social Risks The selection of transformer substation site is relatively scarce, and the substation construction site is relatively concentrated, so the risk of material theft is relatively small. If you ask two workers to take care of the site, you can avoid the risks of being stolen. Political and Legal Risks The scale of Leshan substation is not large, the influence is far less than the Three Gorges project and power transmission from west to east China, so mainly, it is not necessary to consider political risks. Moreover, the construction of Leshan substation is to improve the conditions of the power use of local residents, and promote the economic development of the district. The government and the general public provide great support to the project and the construction standards adopted are accorded with the relevant provisions, which greatly reduce the legal risks. Quantitative Analysis According to the analysis of the main risk factors, in seven kinds of risk factors, we can ignore the natural environment risks, social risks, political and legal risks, but the technical risks, management risks, economic risks, liability risks have different influence on Leshan substation. So we use the analytic hierarchy process (AHP) model to quantitatively analyse the weights of management risks , liability risks , technical risks , and economic risks . Hierarchical structure reflects the relationship among all factors, but the weight of each rule of the rule hierarchy takes different proportion when decision makers measure the goals. Based on this, designing a 3*3 comparison matrix (6) The comparison dimension is 1-9, and the meaning is as follows: element i and element j are of the same importance as that of the upper level; element i and element j are a little more important; element i and element j are important; element i and element j are much more important; , element i and element j are extremely important; , n=1,2,3,4, the importance of element i and element j is between n=1,2,...9, when and only when
and
;
.
Evaluating the relative importance of each hierarchy element to the adjacent hierarchy elements by means of questionnaire survey, the results of the comparison matrix are: (7)
We can get the maximum characteristic root value by using MATLAB to write the analytic hierarchy process programs. So, A is a non-consistent matrix, the more deviates from n, the more serious the nonconsistency of A is. So, the corresponding normalized feature vectors are less able to reflect the actual proportion of each factor. Then it is necessary to do the consistency test, the calculation formula is shown as follows:
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(1) Consistency indicators
;
(2) For n=1,2,...9, Saaty provides the value of average random consistency indicators RI, as shown in the following table 2: TABLE 2 THE VALUE OF AVERAGE RANDOM CONSISTENCY INDICATORS RI WITH DIFFERENT N
n
1
2
3
4
5
6
7
8
9
RI
0
0
0.58
0.90
1.12
1.24
1.32
1.41
1.45
500 sample matrices are constructed, they are generated by random method. Positive reciprocal matrices are randomly selected from the number 1-9 and their reciprocal, the average maximum characteristic root value , the value of RI is defined as: (8) (3) Consistency ratio When CR<0.10, the consistency of the comparison matrix can be accepted, otherwise it will need to be corrected. The calculation of the above formula has been included in the MATLAB program, not being repeated here. The result is: CI=0.0091, CR=0.0176, the consistency of the comparison matrix is acceptable. Assuming the weight vector pointing from the rule hierarchy to the target hierarchy is definition, meets the requirement:
, according to Saatyâ&#x20AC;&#x2122;s (9)
The calculation of the above formula has been also included in the MATLAB program, the result is: (10) Then, the same method is used to construct the paired comparison matrixes pointing from the plan hierarchy to the rule hierarchy, they can be assumed as:
(11)
(12)
(13)
Judging the consistency of the above all matrixes, if the consistency meets the requirements, we can calculate the maximum characteristic value and the weight vector, the results are as follows: as for
,
, CI=0.0790, CR=0.0888, the consistency is acceptable, (14)
as for
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,
, CI=0.0194, CR=0.0218, the consistency is acceptable,
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(15) as for
,
, CI=0.0663, CR=0.0745, the consistency is acceptable, (16)
Let be (17) then the weight vector pointing from the plan hierarchy to the target hierarchy is (18) then (19) TABLE 3 THE WEIGHT PROPORTIONS OF ALL FACTORS
Risk
Weight Proportion
management risks
0.5018
liability risks
0.3150
technical risks
0.1384
economic risks
0.0492
The results show that the weight of the management risks ( ) almost occupy over 1/2, that means the main factor influenced to the construction of Leshan substation is the management risk. Liability risk is a secondary factor. The weight of the technical risks and other conditions is only about 0.14. We can neglect the economic risks whose weight is too small. Therefore, the risk response measures should be considered mainly by these two aspects. Conclusions This paper describes and analyses the existing risk management research under EPC mode. Through the use of basic methods of risk management, the paper empirically tests the application of risk management under EPC mode in Leshan substation engineering through the AHP. According to the results of the assessment and the combination with the actual investigation and analysis of risk factors, the management risks and liability risks are the main influencing factors. And we can take some targeted risk measures to achieve the purpose of reducing the risks of the project. REFERENCES
[1]
He lihuan, Study on the evaluation of contractor’s engineering risks under EPC model [D], Tianjin University, 2008.
[2]
Jin juliang, Wei yiming, Pan jinfeng, Accelerating genetic algorithm for correcting judgement matrix consistency in analytic hierarchy process, Systems Engineering-theory & Practice, 2004, 24(1).Choi, Mihwa. ‚Contesting Imaginaires in Death Rituals during the Northern Song Dynasty.‛ PhD diss., University of Chicago, 2008.
[3]
Li cunbin, Liu yunqi, Li shuke, Optimization of Project Resource Based on Concept Lattice and AHP, International Journal of Management Science and Engineering Research, 2015, 2(1).
[4]
Lu xia, Project risk management for service dispatching system [D], Beijing University of Posts and Telecommunications, 2010.
[5]
Meng weiping, Power grid construction project dynamic risk management and empirical research [D], North China Electric Power University, 2013.
[6]
Qin yebin, Research on the System Construction of the Railway Enterprise Project Contract Management, International Journal of Management Science and Engineering Research, 2015, 2(2).
[7]
Wang zhiwu, Plan and analysis about investment to the project of wutong 220kV substation [D], Southwest Jiaotong University, 2005.
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[8]
International Journal of Management Science and Engineering Research Volume 3 Issue 1, 2016
Zhang junling, Chen liwen, Yin zhijun, Zhao likun, Study on the risk evaluation model for engineering project investment [J], Optimization of Capital Construction, 2004, 25(1).
[9]
Zhang kunsheng, Domestic EPC joint venture mode general contractor risk management research [D], Southwest Jiaotong University, 2011.
Xin Liu, is a postgraduate in Electrical Engineering School of Wuhan University. Shunzhi Zhu, is a postgraduate in Economics and Management School of Wuhan University.
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