How to design a 110kV intelligent substation-INNO

Dengan pembangunan pencawang pintar, prestasi dan kelebihan terminal pintar dan peralatan unit penggabungan telah disahkan secara meluas, tetapi beberapa masalah juga telah didedahkan, seperti: konfigurasi unit penggabungan yang tidak munasabah mengurangkan kebolehpercayaan operasi peralatan perlindungan, kelewatan pensampelan meningkatkan masa tindakan keseluruhan kumpulan perlindungan, dll. Skim teknikal bagi “pensampelan konvensional+GOOSE tripping” untuk peranti perlindungan dalam 220 kV dan ke atas pencawang pintar telah dicadangkan, yang juga mempunyai kepentingan rujukan untuk pembinaan 110 pencawang pintar kV.

1 Gambaran Umum Reka Bentuk

Dalam reka bentuk umum lukisan pembinaan modular untuk pencawang pintar Grid Negeri, 110 Pencawang kV selalunya digunakan sebagai stesen muatan terminal, dengan skala pengubah utama sebanyak 2 units and a typical scheme of single bus segmented (single bus three segmented) or inner bridge (expanded inner bridge) for main wiring. This article takes the 110-A3-3 scheme of expanding the main connection form of the inner bridge as an example to analyze the configuration of the busbar merging unit.

1.1 General Merge Unit Configuration Scheme

In the general design scheme, voltage and current sampling adopts the method of “conventional transformer+merging unit”. Each busbar PT interval is equipped with one intelligent terminal and one merging unit; Two integrated intelligent terminal devices for merging units are installed at intervals between lines and internal bridges; One intelligent integrated device is installed at intervals on the high-voltage side of the main transformer; Kabinet pintar pengubah utama dilengkapi dengan satu terminal pintar dan dua unit penggabungan. Pada bahagian voltan rendah pengubah utama, setiap suis masuk utama dilengkapi dengan dua peranti pintar bersepadu. Peralatan voltan rendah tidak berubah dalam pengoptimuman skim, jadi tiada statistik akan dibuat.

1.2 Perhubungan logik pensampelan voltan

Mengikut garis panduan teknikal untuk pencawang pintar, garisan itu, jambatan dalam, peranti perlindungan pengubah utama, SV, dan maklumat GOOSE mengikut prinsip “perolehan terus dan lompat terus”, dan dihantar dari titik ke titik melalui kabel optik. Mengikut konfigurasi skala akhir skema reka bentuk umum, hubungan logik pensampelan voltan peralatan perlindungan ditunjukkan dalam Rajah 1.

The solid line represents cable wiring, while the dotted line represents optical cable or tail cable wiring. The voltage sampling of the high-voltage side interval merging unit of the line and the main transformer is transmitted through the 9-2 protocol cascade from the busbar merging unit, and can be forwarded to the corresponding line protection, electricity meter, main transformer overload and other devices for use. The voltage sampling of the main transformer protection, backup automatic switching, and low cycle load shedding devices is directly transmitted point-to-point from the busbar merging unit.

Problem analysis

In smart substations, although the reliability of the configuration method of “conventional transformer+merging unit” has been greatly improved compared to the early “electronic transformer+merging unit” mod, the overall reliability of the protection and measurement system has been reduced due to the increased software and hardware modules of the merging unit compared to traditional protection devices, and the increased risk of faults. Selain itu, the poor operating environment of on-site layout has led to a decrease in the overall reliability of the protection and measurement system. In the general design scheme of State Grid Intelligent Substation, yang 110 kV substation is only equipped with 2 sets of busbar merging units according to the final scale, and each set of devices can simultaneously connect to 3 sets of busbar voltage. In this wiring scheme, when one set of merging units fails, it will cause an alarm of the 1/2 main transformer protection device in the station, as well as an alarm or lockout of backup automatic switching, pengukuran dan kawalan, metering and other devices, with a wide range of impact. Considering the risk of faults in busbar merging units, State Grid Corporation of China released the “Standardized Design Specification for Analog Input Merging Units and Intelligent Terminals in Intelligent Substations” dalam 2016, proposing a scheme of configuring one merging unit per busbar segment for single busbar three segmented connection in 110 pencawang kV, seperti yang ditunjukkan dalam Rajah 1. There are still several issues in this plan: (1) When two main transformers are constructed in the first phase and expanded in the final phase, the merging units of each busbar configuration are simultaneously connected to three sets of busbar voltage, which requires corresponding busbar equipment to be powered off, increasing construction risks and technical difficulties. (2) The failure of a single busbar merging unit will cause at least 2 sets of main transformer protection devices to alarm, as well as other parts of protection measurement and control, automatic devices, electricity meters and other equipment to alarm or lock, and the impact range is still relatively large. (3) The sampling voltage from the busbar merging unit to the main transformer protection device and the cascade voltage to other interval merging units require a large number of optical cables (tail cables) to be connected.

Optimization plan

According to the final scale of the entire station, one conventional voltage parallel device will be installed in the 110 kV I and III bus voltage transformer PT control cabinets to achieve voltage parallel function between adjacent busbars. Two bus merging units will be installed in the II bus PT control cabinet to collect the voltage of three bus sections. Two integrated intelligent devices are installed on the line, jambatan dalam, and high-voltage side interval of the main transformer. The merging unit configuration of the intelligent cabinet of the main transformer body is cancelled, and the neutral point zero sequence and gap current are connected to the high-voltage side interval merging unit of the main transformer through cables. The logic relationship of voltage sampling for process level equipment is appropriately simplified.

The bus voltage is connected to the line and the high-voltage side of the main transformer through cables, and the cascading circuit from the bus merging unit is cancelled. The main transformer protection voltage sampling is directly collected from the high-voltage side of the main transformer point to point. The sampling of public equipment such as backup automatic switching and low cycle load shedding can be directly collected from the merging unit of the II bus PT control cabinet. To reduce the impact range of faults in the merging unit, two bus merging units are set up, and the fiber optic interface is reasonably allocated to other public equipment for use.

Compared with the general design scheme, the advantages of this scheme are: (1) enhanced reliability of the interval layer protection measurement and control system. The bus voltage is connected to the line and the main transformer interval merging unit through cables, yang meningkatkan kebolehpercayaan litar dan boleh mengelakkan kesan buruk pensampelan dan penukaran yang disebabkan oleh unit penggabungan bas, serta kegagalan peranti pada perlindungan dan peranti pengukuran selang ini. Apabila unit penggabungan tunggal gagal dalam selang waktu, ia hanya akan menyebabkan penggera untuk set tunggal ukuran perlindungan pengubah utama dan peranti kawalan, dan julat kesan kerosakan akan dikurangkan separuh. (2) Permudahkan pendawaian kabel optik unit cantuman bar bas. Berbanding dengan Rajah 1, Rajah 2 menunjukkan bahawa konfigurasi perlindungan dan peranti automatik kekal tidak berubah. Bilangan peralatan lapisan proses (termasuk 2 peranti selari konvensional) dikurangkan sebanyak 2, dan bilangan port optik unit penggabungan bas yang diduduki dikurangkan daripada 22 kepada 7. (3) The construction is convenient and the power outage range is limited when expanding the III busbar. Only the II busbar needs to cooperate with the power outage, without modifying the I busbar equipment. (4) Reduce equipment procurement costs. The improved plan reduces the number of process layer equipment by 2 unit, and the price of 2 conventional voltage parallel devices is significantly lower than that of the merged unit equipment, resulting in an overall cost reduction. Apabila 110 kV equipment energy meter is placed in the intelligent control room, analog input meters can be used, which is much cheaper than digital input meters and further reduces the cost of engineering equipment.

Shortcomings include: (1) An increase in the number of equipment installed in the busbar control cabinet. For the A3-3 scheme, disebabkan oleh penggabungan susun atur selang sisi voltan tinggi pengubah utama dan selang PT busbar, kabinet kawalan busbar perlu memasang kedua-dua unit penggabungan selang pengubah utama dan unit penggabungan bar bas, serta peralatan terminal pintar. Skim reka bentuk universal asal memerlukan pemasangan tiga peranti dalam setiap kabinet kawalan bar bas; Pelan pengoptimuman memerlukan pemasangan 4 peranti dalam kabinet kawalan bas I dan III, dan 5 peranti dalam kabinet kawalan bas II. Semasa reka bentuk lukisan pembinaan, adalah mungkin untuk berkomunikasi dengan pengeluar peralatan GIS untuk meningkatkan saiz kabinet atau memasang satu kabinet skrin pelindung di dalam bilik GIS. (2) After the voltage circuit adopts cable connection to the line interval intelligent unit, additional cabinet wiring circuits and voltage air switches and other accessories will be added, but the quantity is not large and the circuit wiring is simple, which has little impact on the construction process.

The 110 kV intelligent substation is equipped with a conventional voltage parallel device, and the voltage sampling of the line and main transformer protection is connected to the corresponding interval merging unit through cables. This has obvious advantages in improving the overall reliability of the protection and measurement system and reducing the impact range of single merging unit faults on the protection device. Pada masa yang sama, two busbar merging units are set up to collect the voltage of the 110 kV busbar separately, for use by other public equipment such as backup automatic switching, which can meet the technical characteristics of digital collection and data sharing in intelligent substations.