How do you protect and coordinate distribution equipment from overcurrent and faults?

I believe today's power system protection demands a greater emphasis on security rather than mostly focusing on dependability, which has been extensively researched. Dynamic relay testing, considering network dynamics and the interaction of protective devices, can enhance security. This practice, can be facilitated by digital twins. While digital twins of relays and test devices offer valuable insights, they are insufficient on their own. Creating a comprehensive digital twin of the entire power system, accurately modeling its components, is a significant challenge but essential for optimizing security. After conducting dynamic relay testing, necessary modifications to relay settings can be implemented to further enhance security.

There are few ways to select most suitable OCPD and it mainly depends on: ✔ region you live ans standards You have to follow (IEC, ANSI, GOST and so on) ✔ device type (feeder, motor, electronics ,cable...) ✔ voltage level and expected current ✔ installation application (AC, DC, rail, marine, offshore, hospitals...) ✔ costs and availability of certain equipment Next steps are electrical engineering calculations to select proper size,type and make for Your needs.

Based on my professional experience, conducting simulation studies using reputable software is imperative. The initial step involves performing Load Flow Analysis, a pivotal component of power system engineering aimed at guaranteeing the stable and dependable functioning of electrical networks. Subsequently, you proceed with fault analysis and a coordination study. The effectiveness of the protection is directly proportional to the quality of the input data. Assume nothing!

The type of Over Current Protection devices are based on few major factors like : - Type of Device to be protected - Motor, Generator, Transformer, Feeder, line etc. - Level of voltage and current ( Power ) to be handled - Indoor or outdoor protection - Local standards & regulations - Specific application if any - Also correct selection is current sensors are really important

Na minha experiência, a sofisticação do sistema de proteção está relacionada ao ativo a ser protegido ou criticidade da carga. Para proteção de sistema elétrico de potência, ramais laterais ou transformadores de distribuição são protegidos por elo fusível, devido seu custo e simplicidade no dimensionamento e manutenção. Porém quando esse ramal lateral, atende um carga crítica ou a queima do elo fusível esteja impactando na qualidade de energia de outros ponto do sistema, é necessário a aplicação de outros equipamentos, como por exemplo religadores monofásico ou trifásico.

Also called Protection Discrimination Studies, Selectivity Analysis or Coordination Studies. If we focus on over-current ANSI code 50/51 it usually contains few requirements. ⚡ allow device to operate (long time current) ⚡ allow device to start (inrush current, starting currents, peak loads etc..) ⚡ protect against short circuit faults ⚡ reduce against arc flash energy ⚡ allow for Automatic Disconnection of Supply (required for shock hazard protection) ⚡ allow for selective operation with rest of the electrical system to avoid fault isolation and not whole site. It can be done with hand made calculations however nowadays we use specialized software. This allows for faster design, better quality in complex systems.

When configuring overcurrent protection values, consider load and system characteristics, transformer and circuit breaker ratings, and coordinate with other protective devices for optimal performance. Conduct fault analyses to determine fault types and magnitude, adjusting settings accordingly. Prioritize sensitivity and selectivity, establish time grading, and ensure compliance with industry standards. Plan for periodic testing, maintenance considerations, and anticipate future system expansions. These measures collectively enhance the reliability and efficiency of the protection scheme, promoting effective fault detection and system protection.

Nesta etapa do Estudo de Proteção, na minha experiência eu segregou em 2 momentos: 👆 dimensionamento do elemento de proteção. ✌️ verificação da seletividade com os outros equipamentos. Na etapa do dimensionamento serão estabelecido os limites máximos e mininos. Esses limites dever levar em consideração: - Limite Máximo: suportabilidade do elemento de proteção. Exemplo: limite térmico, curva de suportabilidade, sobrecarga admissível; - Limite Mínimo: sensibilidade do elemento de proteção. E usual utilizar um fator de segurança, quando existe incerteza quanto ao limite de sensibilidade do elemento de proteção. A definição do ajuste irá depender da filosofia adotada no estudo, porém deve ficar dentro dos limites estabelecidos.

Fault current analysis is indeed a critical step. The last sentence is a little misleading. You do not use field measurement to perform fault current analysis. It should be analytical methods and simulation tools. And if you do analytical techniques, you better be skilled in Math, physics, and electrical circuit analysis because you will solve some serious equations .😁

𝗦𝗵𝗼𝗿𝘁 𝗖𝗶𝗿𝗰𝘂𝗶𝘁 𝗖𝘂𝗿𝗿𝗲𝗻𝘁 𝗦𝘁𝘂𝗱𝗶𝗲𝘀 are specialized type of electrical calculations. They provide inputs for more than protection. 𝗔𝗻𝗮𝗹𝘆𝘀𝗶𝘀 𝗱𝗲𝗽𝗲𝗻𝗱𝘀 𝗼𝗻 : ⚡ depends on region/project follow proper standards (IEC60909, IEC61363, ANSI,IEEE C37, GOST R-52735) ⚡ depends on complexity (simplified hand calculation or software model based) ⚡ study reason (protection, cable sizing,panel design or all) 𝗠𝗼𝗱𝗲𝗹𝗹𝗶𝗻𝗴 𝗮𝗻𝗱 𝗔𝗻𝗮𝗹𝘆𝘀𝗶𝘀 𝘀𝘁𝗲𝗽𝘀: ⚡ collect data (avoid assumptions) ⚡ create model for calculations (digital or paper/excel if simplified) ⚡ validate model and input data ⚡ specify scenarios (min,max, generator, UPS, open bus, closed, parallel...) ⚡ select results for further use

Employing fault current analysis is crucial for establishing and coordinating effective protection settings, particularly in critical sites. A valuable approach involves fine-tuned short-circuit analysis. Various standards exist for calculating short circuits, with IEC60909 standing out for its comprehensive methodology. This standard not only considers steady-state fault currents but also introduces a crest factor (K) to determine peak instantaneous short circuit currents. Calculating fault currents for single line-to-ground (SLG), line-to-line ground (LLG), line-to-line (LL), and triple line-to-ground (LLLG) at each node is essential. This in-depth analysis provides the necessary insights for setting reliable protection parameters.

Since it is wide topic of electrical engineering I suggest to follow standards and literature and 𝗯𝗲𝘀𝘁 𝗽𝗹𝗮𝗰𝗲 𝘁𝗼 𝘀𝘁𝗮𝗿𝘁 𝗶𝘀 : ✔ 𝗜𝗘𝗘𝗘 𝟮𝟰𝟮 Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems ✔ IEEE 3000 Standards Collection™ for Industrial & Commercial Power Systems ( new edition of IEEE Colour Books) ✔ 𝗡𝗣𝗔𝗚 book ✔ 𝗣𝗿𝗼𝘁𝗲𝗰𝘁𝗶𝘃𝗲 𝗥𝗲𝗹𝗮𝘆𝗶𝗻g: Principles and Applications by J. Lewis Blackburn (Author), Thomas J. Domin (Author) ✔ Power System Protective Relaying (𝗣𝗼𝘄𝗲𝗿 𝗦𝘆𝘀𝘁𝗲𝗺𝘀 𝗛𝗮𝗻𝗱𝗯𝗼𝗼𝗸) by J. C. Das (Author) Once you know basis it is much easier to use software tools like ETAP, SKM, CYME, Digsilent, PSS Sincal to name few.

Ensuring effective protection coordination is essential for both distribution and transmission networks. The intricate nature of these multi-layered protection schemes demands precise coordination with a buffer to isolate faults, minimizing their impact. Establishing a backup level becomes essential in the event of primary protection failure. Several tools are available for verifying coordination, with curves being particularly useful. These curves serve as a practical method to identify any blind spots in the coordination scheme. Additionally, employing simulation analysis proves beneficial, offering reliable results and allowing the exploration of various settings to determine the optimum configuration.

When it comes to protection it very depends on 𝗲𝘅𝗽𝗲𝗿𝘁𝗶𝘀𝗲 𝗮𝗻𝗱 𝗲𝘅𝗽𝗲𝗿𝗶𝗲𝗻𝗰𝗲 of engineer. There are rules in place and standards to follow however reference points are always changing thus similar applications might differ slightly and still be correct. 𝗚𝗼𝗼𝗱 𝗮𝗽𝗽𝗿𝗼𝗮𝗰𝗵 : ✔ train on the job with more experience engineers ✔ review standards, published papers and white papers (IEEE explore, Cigre, IEC) ✔ standardize design to avoid over engineering Complexity of protection studies are pushing calculations into digital twin models and use of software. In practice protection studies also have 𝘀𝘂𝗯 𝘀𝗽𝗲𝗰𝗶𝗮𝗹𝗶𝘇𝗮𝘁𝗶𝗼𝗻𝘀 : 🔸 HV networks (usually >100 kV, HVDC) 🔸 MV private notworks + LV systems 🔸 LV only