報告書番号

Y09016

タイトル（和文）

わが国電気事業者における高経年送変電設備の管理に関する最近の取り組み

タイトル（英文）

Recent Challenges in the Management of Aging Transmission Facilities in Japanese Electric Power Companies

概要 （図表や脚注は「報告書全文」に掲載しております）

わが国では送変電設備の高経年化が進み、近い将来大量の設備が更新時期を迎える。一方で、電力自由化以降、送変電部門への設備投資は縮小しており、さらに今後は電力需要の堅調な伸びも見込まれず、設備更新に対する予算制約は非常に厳しくなっている。この様な状況において、いかに設備に優先順位付けを行い、更新時期を平準化し、効率的に設備更新を行うかは、各電力会社の課題となっている。本稿では、わが国電気事業者の流通部門（送電・変電）に対してインタビュー調査を行い、設備管理に関する実際の取り組みや考え方、現状の課題等について整理する。
その結果、下記の点が明らかになった。
1. わが国のアセットマネジメントは、各種データや経験値をもとに機器個別の状況に基づいて管理するExperience-Based Method (EBM) と、代表的なデータから機器の余寿命や影響度等を推定し、それらをスコア化して管理を行うRating-Based Method (RBM) に大別できる。
2. 設備量の多い事業者においてRBMを積極的に取り組む傾向があり、今後一層増加すると想定される設備更新工事に備えて、効果的な管理手法を模索している。一方で設備量の少ない事業者においては、予想される更新工事の増加に対してもEBMで充分に管理可能と考えているところもあり、RBMを取り組む必要性に迫られておらず、RBMの採用に対しては消極的であった。
3. RBMに対して積極的に取り組む事業者においては、その手法について模索中であるところが多いが、その主流となるのはリスクマップやその応用手法であった。
4. 事業者は基本的に経験値に基づくEBMの結果を信頼しており、RBMの結果についてもEBMと整合的であることを期待している。しかし、実際には両者が一致しない場合も多く見られている。これは、①設定された評価軸だけでは評価されない要素が残ること、②非計量的要素を正確に数値化できていないこと、③実際の更新工事にあたって重要な判断材料となる工事制約が考慮されていないこと、に基づくと考えられる。現状では、経験的なEBMの結果の方がより重視されており、RBMの結果はあくまで参考値としたり、経験値を明示的にポイント化して加算するなど、EBMと融合しつつRBMを活用する例が多い。
5. ③のRBMで考慮されていない工事制約を、いかに考慮していくかが大きな課題となっている。工事制約には、信頼度維持のための停止制約や機器制約、人的制約等を含む。これらは、実務上考慮されなければならない重要な要素であり、これらを実効的に組み込むことが今後のRBMの最大の課題と考えられる。

概要 （英文）

In recent years, there has been a growing concern regarding investment planning and its optimization methodologies for transmission facilities in power systems. One of the reasons behind this is the increasing number of aged facilities. This implies that electric power companies need considerable investment in the rehabilitation projects of these facilities in the coming decades. However, the budget has been extremely limited, especially for transmission facilities after the liberalization of the electric power market. In this situation, the power transport division of the company has to manage its assets effectively by planning optimum rehabilitation projects under system reliability and gross investment constraints.
Our previous report conducted interview surveys on the status-quo in transmission companies in Europe and US, concerning the implementation of asset management ideas and their experiences. Following this study, the current report conducted an interview survey on the transmission asset management of six Japanese electric power companies.
The report reveals the following:
(a) We roughly categorize the method for prioritization in asset management into two types: experience-based method (EBM) and rating-based method (RBM). In EBM, the condition of a facility is evaluated based on engineers' experience and knowledge, while in RBM, a rating is explicitly given based on several representative data. The companies require RBM to be a generalized model of EBM based on some representative data. And thus, EBM still plays the main role in the transmission asset management of Japanese companies, while several companies have started to employ RBM in addition to EBM, especially for substation facilities.
(b) Companies with a large amount of assets have positively introduced RBM because they will face an increase in rehabilitation projects in coming decades, and thus, need an effective method to support decision making on asset management. On the contrary, those with a small amount of assets think EBM is adequate enough to control their assets.
(c) Companies using RBM are still seeking the appropriate aspects of facility evaluation, for example, the "deterioration" and "impact" of facilities and so forth, as well as effective ways to quantify facility condition perceived by engineers' senses.
(d) Because the companies have essentially trust in and rely on experience and knowledge of engineers, they expect RBM to produce a result consistent with that of EBM. However, they often face the case in which the result of RBM is not consistent with the experience and knowledge of engineers. This will be attributed to (i) the difficulty in the quantification of qualitative items, including experience and knowledge; (ii) factors that are not taken into account in the rating system, in which only representative data is utilized; and (iii) construction constraints, such as relevant project, shutdown, facility-related and human recourse constraints, that are not incorporated into RBM.
(e) Even though construction constraints have a significant impact on the execution of actual construction works, they have not yet been taken into account in RBM. It should be the most important challenge for them to incorporate these constraints into RBM, which will help to reduce the gap between the evaluations of RBM and EBM.
(f) When Japanese companies utilizing RBM are compared with those abroad mentioned in the former report, there is a feature in common, that is, RBM is supported by human-based decision (experience and knowledge of engineers). Meanwhile, it can be said that the rating process is relatively more technical and exhaustive in Japan. Construction constraints were considered by hum

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