A Detailed Testing Procedure of Numerical Differential Protection Relay for EHV Auto Transformer

In power systems, the programmable numerical differential relays are widely used for the protection of generators, bus bars, transformers, shunt reactors, and transmission lines. Retrofitting of relays is the need of the hour because lack of proper testing techniques and misunderstanding of vital procedures may result in under performance of the overall protection system. Lack of relay’s proper testing provokes an unpredictability in its behavior, that may prompt tripping of a healthy power system. Therefore, the main contribution of the paper is to prepare a step-by-step comprehensive procedural guideline for practical implementation of relay testing procedures and a detailed insight analysis of relay’s settings for the protection of an Extra High Voltage (EHV) auto transformer. The experimental results are scrutinized to document a detailed theoretical and technical analysis. Moreover, the paper also covers shortcomings of existing literature by documenting specialized literature that covers all aspects of protection relays, i.e., from basics of electromechanical domain to the technicalities of the numerical differential relay covering its detailed testing from different reputed manufacturers. A secondary injection relay test set is used for detailed testing of differential relay under test, and the S1 Agile software is used for protection relay settings, configuration modification, and detailed analysis.

Setting and Testing of the Out-of-Step Protection at Mongolian Transmission System

Modern distance relays have integrated numerous protection functions, including power-swing blocking and out-of-step or pole-slip tripping functions. The main purpose of the power-swing blocking function is to differentiate faults from power swings and block distance or other relay elements from operating during stable or unstable power swings. Most power-swing blocking elements are based on traditional methods that monitor the positive sequence impedance rate. The required settings for the power-swing blocking elements could be difficult to calculate in many applications, particularly those where fast swings can be expected. For these cases, extensive stability studies are necessary to determine the fastest rate of possible power swings. This paper presents a detailed step-by-step method for settings calculation of out-of-step (OOS) protection, both blocking and tripping functions considering a generic two-source system. Then the method is applied to define the protection relay settings installed at the interconnection between the Russian and Mongolian power systems, as it is crucial to feed the demand-rich Mongolian power system. In this paper, a specific impedance method is used for defining the OOS protection settings. This paper innovates by testing the settings using the recordings of the major events of 15 September 2018 in two approaches: hybrid co-simulation and cyber-physical. Both tests have demonstrated the appropriate performance of the proposed settings and proving the proposed methodology works appropriately.

Experimental platform tests for setting performances of distance protection installed in Biskra-Batna of the Algerian transmission line

The modern power system is equipped with protection system based on advanced technology through the use of digital multifunction relay, control system and intelligent selectivity, whose purpose is to ensure maximum security and service continuity of protection relay in the presence of various fault currents. Distance protection is an important protection required in high voltage transmission lines. In this paper, experimental platform tests have been performed and proposed for setting and evaluation the performances of distance protection named Micom P442 installed in Biskra-Batna of the Algerian transmission power system. The performances of the distance protection have been evaluated under various short circuits. In this study, experimental result based single phase fault to ground is analysed and discussed. Experimental results based on the proposed platform tests in terms of precision in detecting faults at various locations and trigger times confirm the efficiency and particularity of the proposed experimental platform tests.

Simulasi ETAP untuk Evaluasi Proteksi Gangguan Tegangan Lebih Generator Unit 3 PLTP Kamojang

AbstrakPada penelitian ini dilakukan evaluasi proteksi gangguan tegangan lebih pada generator Unit 3 PLTP Kamojang yang diproteksi oleh sebuah relay tegangan lebih menggunakan simulasi pada software ETAP. Simulasi dilakukan untuk melihat bagaimana cara kerja relay tegangan lebih dan bentuk tegangan lebih yang terjadi pada terminal generator. Skenario simulasi yang digunakan yaitu melakukan pelepasan beban 50,7 MW dan relay yang digunakan dalam simulasi berfungsi untuk menyalakan alarm saat terjadi tegangan lebih. Hasil simulasi memperlihatkan bahwa pada saat terjadi pelepasan beban, relay tegangan lebih menyalakan alarm 1,1 detik setelah membaca tegangan naik hingga 13 kV atau sebesar 110% dari tegangan nominalnya, kemudian tegangan terminal generator naik hingga 13,2 kV hingga kembali ke kondisi steady state 5 detik setelah terjadi kenaikkan tegangan. Hasil simulasi tersebut menunjukkan bahwa relay tegangan lebih yang terpasang pada terminal generator Unit 3 bekerja sesuai dengan fungsinya yaitu untuk memberikan alarm ketika tegangan lebih terjadi.Kata kunci: pelepasan beban, proteksi generator, relay proteksi, simulasi generator, tegangan lebihAbstractThis study evaluates overvoltage fault protection on the generator Unit 3 PLTP Kamojang which is protected by an overvoltage relay using simulation on ETAP software. Simulations are carried out to see how the overvoltage relay works and the form of overvoltage that occurs at the generator terminals. The scenario used is by do a load shedding of 53,3MW, the relay used in this simulation has a function to turn on the alarm when overvoltage occurs. The results show that when a load shedding occurs, the overvoltage relay turns on the alarm 1,1 seconds after reading the voltage up to 13 kV or 110% of the nominal voltage, then the generator terminal voltage rises to 13.2 kV until it returns to steady state 5 seconds after the voltage increase. The simulation results indicate that the overvoltage relay installed at the generator terminal Unit 3 works according to its function, namely to provide a warning when an overvoltage occurs.Keywords: generator protection, load shedding, overvoltage, protection relay, generator simulation

A Novel Exact Analytical Solution Based on Kloss Equation towards Accurate Speed-Time Characteristics Modeling of Induction Machines during No-Load Direct Startups

The acceleration time of induction machines (IMs) is essential for proper protection-relay settings of the machine to prevent voltage sags in local power areas. In this paper, mathematical modeling of IMs’ speed-time characteristics during no-load direct startup has been presented. Unlike the approaches presented in the literature, the proposed approach includes the bearing losses, in which two expressions of the speed-time characteristics of IMs during no-load direct startup are derived. The first expression was derived based on the Kloss equation used for representing the torque, and the second expression was derived based on the torque expression determined from the Thevenin equivalent circuit of the machine. The derived expressions’ accuracy was validated using laboratory measurement and computer simulation approaches. The results obtained show a good agreement between the measured and simulated speed-time characteristics of two IMs. Finally, the proposed formulations can provide a simple analytical base to enable accurate IM modeling.

Study on a protection coordination approach for over-current relays in distribution generator-integrated distribution networks

Sự hiện diện của nguồn phân tán DG (Distributed Generator) đã gây ra những thách thức đến việc duy trì độ tin cậy của những OCPR quá dòng OCPR (Over-current Protection Relay) khi hoạt động để bảo vệ lưới điện phân phối (LĐPP). Trong quá trình vận hành để đảm bảo cung cấp điện cho LĐPP, những đặc tính vận hành của nguồn DG đã làm thay đổi đáng kể giá trị dòng điện sự cố và đây là nguyên nhân chính dẫn đến những hiện tượng OCPR hoạt động không tin cậy, chẳng hạn như mất tính chọn lọc, giảm độ nhạy, hoạt động vượt cấp hoặc hoạt động đồng thời. Do đó, việc điều phối những OCPR thuộc hệ thống bảo vệ trên LĐPP có xem xét đến những đặc tính vận hành của nguồn DG nhằm đảm bảo tính phối hợp khi hoạt động là cần thiết. Trong nghiên cứu này, nhóm tác giả sẽ giới thiệu về một phương pháp điều phối bảo vệ OCPCO (Over-current Protection Coordination Optimization) dành cho hệ thống bảo vệ của LĐPP có tích hợp nguồn DG. Cụ thể, phương pháp OCPCO này được phát triển dựa vào việc sử dụng kết quả phân tích ngắn mạch kết hợp với giải thuật tìm kiếm GSA (Gravitational Search Algorithm) để xác định các hệ số điều phối A, B, C và TDS (Time Dial Setting) phù hợp với từng trạng thái vận hành của LĐPP có tích hợp nguồn DG, đặc biệt là sau khi LĐPP đã được tái cấu trúc để cách ly sự cố và khôi phục cung cấp điện. Thông qua hàm mục tiêu về tổng thời gian đảm bảo phối hợp CTI (Coordination Time Interval) cho phép giữa những OCPR liền kề nhau, phương án điều phối trị số chỉnh định sẽ được đề xuất và cập nhật đến từng OCPR thông qua hạ tầng mạng truyền dẫn thông tin. Mô hình LĐPP có tích hợp nguồn DG được nhóm tác giả xây dựng dựa vào LĐPP thực tế bằng phần mềm ETAP, để phục vụ cho việc phân tích ngắn mạch và kiểm tra tính khả thi của phương pháp OCPCO đề xuất. Hơn nữa, kết quả điều phối bảo vệ bằng giải thuật GSA sẽ được so sánh với những kết quả xuất ra từ giải thuật PSO&GSA và GA nhằm làm cơ sở kiểm tra tính phù hợp khi điều phối những OCPR trên LĐPP có tích hợp nguồn DG.

Mutual Coupling Compensation Techniques Used for Distance Protection of Parallel Lines

When a distance relay protects a transmission line located on a dual circuit tower, a coupling effect will occur between the two circuits. Transposition of the circuits can reduce the mutual impedances, but this does not cater to the zero-sequence mutual coupling impedance during earth faults. As a result, the impedance measured by a distance relay under phase-to-earth fault conditions in these circumstances will not represent the correct impedance to the fault point unless these effects are taken into account. On multi-circuit lines, primarily if they operate in parallel, a zero-sequence mutual coupling should be considered when calculating settings for distance protection function. A 220 kV parallel line sharing the same tower was analysed using DigSilent Power Factory in the simulations. Phase-to-earth faults in different configurations were analysed on this system, and the reach of the protection relay was then estimated for operation. The results confirm how a protection relay can overreach and underreach in a distance protection scheme due to the influence of mutual coupling.