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肯尼亞低壓配電網規劃設計的技術問題 ,Technical aspects to planning and designing LV distribution n

肯尼亞低壓配電網規劃設計的技術問題 

Technical aspects to planning and designing LV distribution networks

智能電網風靡一時,但在很大程度上,當局關心的是增加冗余和減少損失。以下清單將以肯尼亞低壓電網為例,力求使規劃更容易,設計更安全。

本文首次出現在ESI非洲版4-2019年。

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在此處閱讀完整的digimag或訂閱此處接收打印副本
2018年,肯尼亞政府與世界銀行合作推出了《肯尼亞國家電氣化戰略》,為到2022年實現所有肯尼亞人普遍用電提供了路線圖。根據政府的2030年愿景,普及電力是實現肯尼亞發展目標和實現其四大議程優先事項的關鍵:即負擔得起的住房、制造業、糧食安全和全民保健。此外,為了確保電氣化戰略得到有效實現,需要建立一個更強大和更靈活的網格,通過建設冗余和減少損失。

能源和石油管理局(EPRA)電力和可再生能源局局長約瑟夫·奧基奇(Joseph Oketch)強調:“有兩類損失需要注意。首先,由于配電距離、導線尺寸和配電基礎設施質量造成的技術損失;其次,由于故意破壞和盜竊造成的未計量電源造成的商業損失。”

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肯尼亞國家配電網規范(KNDC)
《電網規范》規定了各種用戶接入和使用配電網及操作系統的規章制度。國家發展委員會的目標是提高肯尼亞電力系統以透明和非歧視的方式安全、可靠、高效和經濟地規劃和運行的能力。它規定了配電系統的所有配電網服務提供商(DNSP)和配電網用戶(DNU)(見上文信息框)訪問和使用配電系統的義務。
低壓配電網
低壓電網或二次網是配電網的一部分,它將電能從配電變壓器輸送到終端用戶的電能表。這個網絡可能包括國內和輕工業和商業消費者。低壓線路從變壓器的低壓套管開始,到配電線路,再到用戶的廠用掉電線路,在規劃和設計時考慮了幾個方面。
主要規劃和設計考慮因素
所有低壓配電網,無論是政府所有還是私營部門所有,均按照肯尼亞國家配電網規范進行開發。在這種情況下,所有網絡服務提供商都必須規劃、設計、維護和運行其配電網,以允許將電力從發電機轉移到用戶手中,同時提供與電力系統相關的所有設施或設備。
配電網用戶可以尋求發電廠與配電系統的連接,或配電系統的新連接或修改連接。因此,網絡服務提供商將向網絡用戶提供相關的配電系統規范和要求,以幫助他們規劃和采購新的或修改后的配電系統連接設備。
審查連接容量要求:小型、中型和大型
小連接(10kVA及以下)
?連接容量(kVA)。
?待連接設備的類型和電氣負荷,例如電機、炊具、電氣空間和水電氣加熱、空調或制冷的數量和尺寸。
?需要新連接或修改連接的日期。
介質連接(高達2兆瓦)
?預期的配電連接點;地理和電氣。
?需要連接的日期。
現有席和設備布置的單線圖,顯示設備額定值和操作參數。
?待連接設備的類型和電氣負載,例如電機、電加熱、空調或制冷的數量和尺寸。
大連接(大于2兆瓦)
?負載數據。
?負載類型和控制裝置(例如,受控整流器或大型電機驅動器和所用起動器類型)。
高峰需求席上各階段的最大負荷。
?配電系統高峰需求日和輸電系統高峰需求日的有功和無功需求曲線(48 x半小時平均估計值)。
研究、評估和利益相關者參與要求
(a) 分布影響研究
評估所提出的連接或修改對配電系統上現有連接的影響,之后將批準連接并達成連接協議。
(b) 負荷評估
確定用戶的負荷要求。
(c) 電源點測量
以確定距最近變壓器的距離。如果距離超過600米,則需要升級到高壓和新變壓器。
(d) 成本效益分析
網絡建設分析,包括項目的商業和社會可行性。
(e) 環境和社會影響評估
這是國家環境管理的一個關鍵要求
當局(NEMA),評估和減輕任何環境和社會風險和影響。
(f) 利益相關者參與
這是在縣和社區層面進行的,以了解現有的計劃,使該地區電氣化,儲備政府土地,以及使用的方式進行談判。
安全要求
?電纜離地高度。
?電纜深度。
?與房屋的距離。
?絕緣協調和防雷[Ed:有關防雷保護的更多信息,請參見第22頁]。
?接地細節。
網絡設計要求
?連接點設計。
?連接點附近的物理布局。
?主保護和后備保護。
?控制特性。
?通信和警報。
?故障等級和故障清除時間。
?開關和隔離設施和程序。
?計量裝置。
最終用戶連接要求
?帶有保護細節的單線圖。
?用戶提供的任何計量設備的計量系統設計細節。
?現場所有設備的總布置圖。
每一個新的或變電所的總布置圖顯示所有出口席和所有電氣設備的位置。
?所有新開關設備和變壓器的試驗證書,包括用于計量目的的測量變壓器。
?建議的接地電纜和其他設備的方法,以符合適用的監管文書。
?經批準的測試機構出具的工廠和接地網測試證書。
?所有斷路器的二次注入和跳閘試驗證書。
?證明所有新設備在連接到電源之前都經過檢查。
?業務安排。
實施低壓網絡的挑戰
?在沒有政府土地儲備的情況下,獲得通行權可能是乏味和昂貴的。
與現有變壓器相比,更長的距離意味著將系統升級到高電壓(HV)級和新變壓器席上的額外投資。
?在配送過程中,如果配送基礎設施差或配送距離較長,以及由于供應不足,可能會出現高損失。
?低負荷要求的區域普遍存在,使其在商業上不可行。
?低壓基礎設施和資產很容易被破壞。
?地下管線很容易損壞,并構成安全威脅。
?由于易于在消費點操縱低壓網絡,因此存在非法連接。
世界銀行支持肯尼亞的旗艦“最后一英里連通性方案”和“貧民窟電氣化方案”,這兩個方案在過去五年中促進了該國電力供應的顯著擴大。據世界銀行能源和能源采掘主任盧西奧·莫納里說,肯尼亞的經驗為其他非洲國家提供了寶貴的經驗,包括政府在努力擴大和改善電力供應方面的承諾、激勵政策和監管。電噴霧
關于作者
Jacinta Murunga是能源和社會可持續發展專業人士,也是能源和社會問題的自由研究員和作家。Jacinta熱衷于社會可持續性、環境和社會保障,并致力于利用她10年的經驗,幫助社區、私人和公共機構分別實現可持續性和E&S合規。
工具書類
?肯尼亞2017年國家配電網規范
?肯尼亞啟動雄心勃勃的計劃,到2022年向所有公民提供電力,世界銀行,2018年12月
?肯尼亞繪制了實現普及電力的路徑圖,世界銀行,2018年12月

2020年非洲和中東地區電力及能源展覽會:

2020年南非能源展:http://www.mnntfp.live/show-839.html

 2020年沙特電力展:  http://www.mnntfp.live/show-943.html

2020年東非肯尼亞電力展:http://www.mnntfp.live/show-938.html

2020年北非埃及電力展:http://www.mnntfp.live/show-941.html

  2020年西非尼日利亞電力展:http://www.mnntfp.live/show-944.html


原文:

Technical aspects to planning and designing LV distribution networks

                                                                         

distribution networks
Featured image: Stock

Smart grids are all the rage but for the most part, authorities are concerned with building in redundancies and reducing losses. Using the Kenyan low voltage (LV) network as an example, the following checklist will endeavour to make for easier planning and safer designs.

This article first appeared in ESI Africa Issue 4-2019.
Read the full digimag here or subscribe to receive a print copy here

In 2018, the Kenyan government launched the Kenya National Electrification Strategy (KNES) in partnership with the World Bank, to provide a roadmap to achieving universal access to electricity for all Kenyans by 2022. Under the government’s Vision 2030, universal access to electricity is key to meeting Kenya’s development goals and delivering on its Big Four Agenda priorities: namely affordable housing, manufacturing, food security, and universal healthcare. Furthermore, to ensure that electrification strategies are effectively achieved, there is need to build a stronger and more flexible grid by building in redundancies and reducing losses.

Engineer Joseph Oketch, the Director: Electricity and Renewable Energy Directorate at the Energy and Petroleum Regulatory Authority (EPRA), stresses: “There are two types of losses to be aware of. Firstly, technical losses due to distribution distance, size of conductor, and quality of distribution infrastructure; and secondly, commercial losses due to unmetered power supply, resulting from vandalism and theft.”

Kenya National Distribution Grid Code (KNDC)

The grid code defines the rules and regulations for various users for accessing and using the distribution network and operation systems. The objective of the KNDC is to improve the ability of Kenya’s power system to be planned and operated safely, reliably, efficiently, and economically in a transparent and non-discriminatory manner. It establishes the obligations for all distribution network service providers (DNSP) and distribution network users (DNU) of the distribution system (see Info Box above) for accessing and using the distribution system.

Low voltage (LV) distribution network

A low-voltage network or secondary network is a part of electric power distribution, which carries electric energy from distribution transformers to electricity meters of end customers. This network may include domestic and light industrial and commercial consumers. Low voltage lines start from LV bushings of transformers, to distribution lines to customers’ service drop-in lines, and several aspects are taken into consideration during their planning and designing.

Key planning and design considerations

All low voltage distribution networks, whether owned by government or the private sector, are developed in accordance with the Kenya National Distribution Grid Code. In this case, all network service providers are required to plan, design, maintain and operate their distribution networks to allow the transfer of power from generators to consumers with all facilities or equipment associated with the power system in service.

Distribution network users can seek a connection of a generating plant to the distribution system or a new or modified connection of the distribution system. The network service provider will therefore furnish the network user with the relevant distribution system specifications and requirements to assist them in planning and procurement of equipment for a new or modified connection to the distribution system.

Reviewing the connection capacity requirements: Small, medium and large

Small connections (10kVA and below)

? Connection capacity in kVA.

? Type and electrical loading of equipment to be connected, e.g. number and size of motors, cookers, electrical space and water electrical heating, air conditioning, or refrigeration.

? The date when the new or modified connection is required.

Medium connections (up to 2MVA)

? Expected connection point to the distributions; geographical and electrical.

? The date when connection is required.

? Single line diagrams of existing and proposed arrangements of main plant and apparatus showing the equipment rating and operating parameters.

? Type and electrical loading of equipment to be connected, e.g. number and size of motors, electrical heating, air conditioning, or refrigeration.

Large connections (greater than 2MVA)

? The load data.

? Type of load and control arrangements (e.g. controlled rectifier or large motor drives and type of starter employed).

? Maximum load on each phase at the time of Peak Demand.

? Demand profiles (48 x half hour average estimates) for Active and Reactive Power Demand for the day of Distribution System Peak Demand and for the day of the Transmission System Peak Demand.

Studies, assessments and stakeholder engagement requirements

(a) Distribution Impact Studies

To evaluate the impact of the proposed connection or modification to an existing connection on the Distribution System, after which the connection will be approved and a connection agreement reached.

(b) Load Assessment

To ascertain the load requirements for consumers.

(c) Survey of the Power Point

To determine the distance from the nearest transformer. If the distance is more than 600 metres an upgrade to high voltage and new transformers is required.

(d) Cost-Benefit Analysis

Analysis of constructing the network, including the commercial and social feasibility of the project.

(e) Environmental and Social Impact Assessment

This is a key requirement from the National Environment Management

Authority (NEMA), to assess and mitigate any environmental and social risks and impacts.

(f) Stakeholder Engagement

This is conducted at the county and community levels, to understand existing plans to electrify the area, reserve government land to be utilised as well as way leaves to be negotiated.

Safety requirements

? Height of the cables from the ground.

? Depth of cables.

? Distance from houses.

? Insulation coordination and lightning protection [Ed: see page 22 for more on lightning protection].

? Earthing details.

Network design requirements

? Design at the connection point.

? Physical layout adjacent to the connection point.

? Primary protection and backup protection.

? Control characteristics.

? Communications and alarms.

? Fault levels and fault clearance times.

? Switching and isolation facilities and procedures.

? Metering installations.

End-user connection requirements

? A single line diagram with the protection details.

? Metering system design details for any metering equipment being provided by the consumer.

? A general arrangement locating all the equipment on site.

? A general arrangement for each new or altered substation showing all exits and the position of all electrical equipment.

? Test certificates for all new switchgear and transformers, including measurement transformers to be used for metering purposes.

? The proposed methods of earthing cables and other equipment to comply with applicable regulatory instruments.

? Plant and earth grid test certificates from approved test authorities.

? A secondary injection and trip test certificate on all circuit breakers.

? Certification that all new equipment has been inspected before being connected to the supply.

? Operational arrangements.

Challenges implementing LV networks

? Acquisition of wayleaves can be tedious and expensive in cases where there is no government land reserve.

? Longer distance from existing transformers means additional investments in upgrading system to a high voltage (HV) level and new transformers.

? High losses can be experienced during distribution, in cases of poor distribution infrastructure or longer distribution distances, and due to unmetered supply.

? Areas with low load requirements are prevalent, making it commercially unviable.

? LV infrastructure and assets are easily vandalised.

? Underground lines can be easily damaged and pose a safety threat.

? Illegal connections due to ease of manipulating LV networks at consumer points.

The World Bank has supported Kenya’s flagship Last Mile Connectivity Programme and its Slum Electrification Programme, which have contributed to the phenomenal expansion of electricity access in the country in the last five years. According to Lucio Monari, director for energy and energy extractives at the World Bank, the Kenyan experience provides valuable lessons for other African countries in terms of the government’s commitment, incentive policies and regulation in efforts to expand and improve access to electricity. ESI

About the author
Jacinta Murunga is an energy and social sustainability professional, as well as a freelance researcher and writer on energy and social issues. Jacinta is passionate about social sustainability, environmental and social safeguards and is driven to make a difference using her 10 years’ experience, assisting communities, and private and public institutions to attain sustainability and E&S compliance respectively.

References
? Kenya National Distribution Grid Code of 2017
? Kenya Launches Ambitious Plan to Provide Electricity to all Citizens by 2022, World Bank, December 2018
? Kenya Charts Path to Achieving Universal Access to Electricity, World Bank, December 2018



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