122 research outputs found
Testing of the Enhanced Frequency Control Capability (EFCC) Scheme : Part 1 - Local Operational Mode
No full textThis report presents the methods and results relating to tests conducted at the Power Network Demonstration Centre (PNDC) at the University of Strathclyde (UoS) for validating the Enhanced Frequency Control Capability (EFCC) scheme. This work is part of the EFCC project led by National Grid under Ofgem’s Network Innovation Competition (NIC) funding framework. The EFCC scheme has two main operational modes: wide-area mode, used when wide-area communication links are available and with sufficiently good quality; local mode, when the wide-area communication links are lost or have relatively poor quality. The Local Controller (LC) within the scheme can also be intentionally set to operate in local mode if required. The test activities at the PNDC have been conducted in two main stages, corresponding to the two operational modes mentioned earlier. The first stage is focused on testing the local mode, while the second stage concentrates on testing the wide-area operational mode using a Power-Hardware-in-the-Loop (P-HiL) test setup, which was established and configured specifically for the EFCC testing regime. For the wide-area mode tests, the impact of communication performance on the EFCC scheme's operation was also evaluated. Therefore, the final test report contains three main parts, i.e. local mode tests, wide-area mode tests (with ideal communication network conditions), and communication impact tests. This document constitutes the first part of the overall final test report and presents the results from the first stage of tests concerned with evaluating EFCC performance when operating in local mode. In this mode, the LC does not have access to wide-area measurement signals (or it neglects those signals if the controller has been intentionally set to operate in local mode). Test results for the EFCC system’s performance in wide-area mode and the impact of communication performance on EFCC will be reported in separate documents
Testing of the Enhanced Frequency Control Capability (EFCC) Scheme : Part 3 - Impact of Communication Performance on the EFCC Operation
No full textThis report presents the methods and results of the tests conducted at the Power Network Demonstration Centre (PNDC) at the University of Strathclyde (UoS) to evaluate the impact of communication performance on the operation of the Enhanced Frequency Control Capability (EFCC) scheme. This work is part of the EFCC project led by National Grid under Ofgem’s Network Innovation Competition (NIC) funding framework. This report is Part 3 of a set of three reports, where the other two reports focus on the testing of the EFCC scheme’s local and wide-area operational modes respectively. The operation of the EFCC scheme requires two main types of communication networks, i.e. the wide-area communication between the Regional Aggregators (RAs) and Local Controllers (LCs), and regional communication between Phasor Measurement Units (PMUs) and RAs. In this work, both types of communication networks were emulated using a communication emulator and the impact of the communication performance of both networks have been evaluated for the following communication parameters: latency, latency with jitter, the rate of loss of packets and Bit Error Rate (BER). The tests firstly evaluated how these different emulated communication conditions would affect the EFCC controllers in receiving and processing the data (i.e. how the confidence levels in the EFCC controllers were affected under the various emulated conditions). Then the performance of the EFCC scheme during frequency and fault events was tested with the emulated communication conditions. The EFCC controllers handle degraded communication conditions through buffering data over a certain time window (referred as "buffering window") and perform appropriate interpolation to deal with data losses. In the fixed latency tests, it was found that, for 100 ms buffering window, the maximum latency limits at the regional and wide-area networks are around 82 ms and 78 ms respectively. For LCs, even if one of communication links between the RAs and the LCs experience a communication latency larger than the maximum limit, it could lead to the EFCC controllers exhibiting different behaviours. If the LC misses data from two out of three RAs (i.e. the confidence level becomes smaller than the configurable threshold of 50%), this will lead to the LC losing wide area visibility and it will automatically switch to local mode
Testing of the Enhanced Frequency Control Capability (EFCC) Scheme : Part 2 - Wide Area Mode Tests
No full textThis report presents the methods and results relating to tests conducted at the Power Networks Demonstration Centre (PNDC) at the University of Strathclyde (UoS) concerned with investigating and validating the performance and benefits of the Enhanced Frequency Control Capability (EFCC) scheme. This work is part of the EFCC project led by National Grid (NG) under Ofgem’s Network Innovation Competition (NIC) funding framework. This report is Part 2 of a set of total 3 reports. The tests presented in this report focus on the evaluation of the performance of the EFCC scheme when operating in its wide-area mode, where all communication links are enabled and possess sufficiently good quality. The other two reports focus on the testing of the EFCC scheme’s local operational mode (Part1) and upon the evaluation of the impact of communication performance on the wide-area operation of the scheme (Part 3)
Deployment of synchronous compensators in the GB transmission network to address challenges from increasing renewable generation
No full textThis work proposes to investigate the benefits of synchronous compensation in addressing concerns pertinent to: • the quantitative study of the benefits of synchronous compensation to system rate of change of frequency (RoCoF); • the quantitative study of the impact that synchronous compensation has on the risk of loss of commutation on the Western Link
Enhanced frequency control capability (EFCC) project
No full textEFCC aims at developing and demonstrating a wide area monitoring and control scheme that is capable of deploying fast and coordinated frequency response using a variety of resources such as PV, energy storage, wind farms, demand side resources (DSR), and CCGTs. The successful implementation of this project is expected to enable faster response than existing schemes and lead to savings of £150m-£200m per annum by 2020
Design of an intelligent system for validation of protection settings
No full textThe reliable operation of protection systems depends on the correct settings of protective devices, which can be extremely numerous and complex within modern protection schemes. It has been realised that, despite multiple instances of checking, and verification and quality control processes, setting errors may remain undetected until an in-service mal-operation event is experienced. Furthermore, while the network evolves, the originally correct settings may be rendered erroneous under certain specific (unanticipated) situations. These issues present a strong need for a solution that allows comprehensive validation of settings and checking of the actual performance of the protection system with the settings applied in a variety of operational contexts. To address these requirements, this thesis presents the outcomes of research concerned with developing and demonstrating an intelligent system-based solution incorporating hybrid Rule-Based (RB) and Model-Based (MB) approaches - the system has been termed the Power system Protection Smart Tool (PPST). It is shown that the combined RB and MB approaches are effective in complementing each other for the settings and performance validation tasks with enhanced reliability and automation. The advantages of the proposed methodology are demonstrated through case studies with actual network and settings data. To maximise the applicability of the developed scheme, the considerable challenges of automating the use of existing settings data stored in a wide range of proprietary formats is also reported. A solution that has been developed which represents settings using IEC 61850 standardised file format and data model is described, along with a proposed methodology that will enable power utilities to migrate from existing approaches to the proposed future approach based on standardised protection settings. Adoption of these recommendations would facilitate a shift from protection systems being largely single-vendor solutions to becoming truly open platforms, capable of supporting the settings validation system as reported in this thesis and any other future applications that require access to and/or manipulation of protection settings. Conclusions and future work concerned with moving the developed system to becoming a "business as usual" application are also included.The reliable operation of protection systems depends on the correct settings of protective devices, which can be extremely numerous and complex within modern protection schemes. It has been realised that, despite multiple instances of checking, and verification and quality control processes, setting errors may remain undetected until an in-service mal-operation event is experienced. Furthermore, while the network evolves, the originally correct settings may be rendered erroneous under certain specific (unanticipated) situations. These issues present a strong need for a solution that allows comprehensive validation of settings and checking of the actual performance of the protection system with the settings applied in a variety of operational contexts. To address these requirements, this thesis presents the outcomes of research concerned with developing and demonstrating an intelligent system-based solution incorporating hybrid Rule-Based (RB) and Model-Based (MB) approaches - the system has been termed the Power system Protection Smart Tool (PPST). It is shown that the combined RB and MB approaches are effective in complementing each other for the settings and performance validation tasks with enhanced reliability and automation. The advantages of the proposed methodology are demonstrated through case studies with actual network and settings data. To maximise the applicability of the developed scheme, the considerable challenges of automating the use of existing settings data stored in a wide range of proprietary formats is also reported. A solution that has been developed which represents settings using IEC 61850 standardised file format and data model is described, along with a proposed methodology that will enable power utilities to migrate from existing approaches to the proposed future approach based on standardised protection settings. Adoption of these recommendations would facilitate a shift from protection systems being largely single-vendor solutions to becoming truly open platforms, capable of supporting the settings validation system as reported in this thesis and any other future applications that require access to and/or manipulation of protection settings. Conclusions and future work concerned with moving the developed system to becoming a "business as usual" application are also included
Implications of reduced fault level and its relationship to system strength : a Scotland case study
No full textThe integration of Inverter Based Resources (IBRs), which displace traditional Synchronous Generators (SGs), presents new challenges to power system operation. SGs naturally provide voltage source behaviour, allowing them to be represented by a voltage source behind an equivalent impedance. In contrast with SGs, IBRs' behaviour during faults is typically like a controlled current source, and their responses to network faults are driven by their control strategies and the current limited capacity of the converter, resulting in a reduced fault current infeed during network faults. As a fault level can be seen as a measure of the equivalent system impedance, based on the 50 Hz Thevenin equivalent, it has also been used as a measure of "system strength", e.g. through the use of various Short Circuit Ratio (SCR) metrics. As a result, the terms "fault level" and "system strength" are sometimes used interchangeably, which may be largely valid for SG dominated systems. However, the fault level metric does not always capture all aspects of system behaviour in the context of high IBR penetration. Hence, particularly in systems which have a high number of IBRs relative to SGs, this paper argues that there is a need to make a clearer distinction between the low fault level issues and other challenges. The fault level remains a useful metric in the context of power system protection and to assess system characteristics during faults, such as the voltage depression. Meanwhile, other system challenges include a high voltage sensitivity during quasi-steady state system conditions, such as IBR control interactions. This paper has assessed fault levels in the Scottish transmission area of the Great Britain (GB) power system, an area which has a high number of IBRs and very few large SGs, some of which are close to retirement. These factors have motivated the system operator (SO) to launch a tender exercise – the Stability Pathfinder (SPf) Phase 2 – that is seeking new sources of fault current to connect to the system. Although the SPf has been motivated by closure of SGs, it is shown in this paper that, at many locations, equipment outages can reduce local fault levels more than the status of the available large SG units, and that fault level contributions from SGs are relatively localised. In addition, a sub-synchronous oscillation event in August 2021 suggests that challenges related to a high voltage sensitivity also exist in Scotland. Moreover, the fault levels during the event were not unusually low. Hence, considering the limitations of fault level as a metric for quasi-steady state voltage sensitivity challenges and that the observed fault levels can already be low and are not very sensitive to the anticipated closure of SGs, it is concluded that procurement of fault level alone may not be adequate to address some of the operational issues in the Scottish transmission system with further integration of IBRs. More work should be done on defining the exact metrics for quantifying the system needs in order to ensure security of supply in the most cost-effective manner
Active phase control to enhance distance relay in converter-interfaced renewable energy systems
No full textFor the distance protection applied in converter-interfaced renewable energy systems, various AC fault ride-through strategies of converter-interfaced sources will cause a large phase difference between the operating current of the distance relay and the fault current, resulting in the mal-operation of the distance relay. To overcome this issue, this paper proposes an active phase control for the converter-interfaced renewable energy systems to enhance the reliability of the distance relay. This control scheme firstly calculates the phase difference between operating current and fault current by only using local measurements. Then, the phase difference is eliminated via phase angle adjustment. To verify the effectiveness of the proposed control scheme. The performance of the proposed method is tested in a radial three-terminal system and the IEEE 14-bus system in PSCAD/EMTD
Feasibility of achieving fast RoCoF-based LOM protection – a case study of Hong Kong distribution network
No full textDistributed Energy Resources (DERs) are playing a critical role in the energy landscape to facilitate the decarbonisation of energy systems. One of the key requirements for the safe integration of DERs is to ensure the Loss of Mains (LoM) protection is sufficiently dependable and secure so that it can effectively detect islanding conditions while avoiding maloperation during other non-LOM grid disturbances (e.g. faults). This paper aims to assess the feasibility of achieving fast and reliable islanding detection using a commercially available Rate of Change of Frequency (RoCoF) based LoM relay. The study is undertaken on a section of the distribution system in Hong Kong (HK) where fast LoM protection operation (<260ms) is required due to the short time delay of an existing auto-reclose scheme. Systematic evaluation of the LoM relay performance both in terms of dependability and security is undertaken using Hardware-in-the-Loop (HiL) injection implemented on a Real-time Digital Simulator (RTDS). Based on the test results and detailed analysis, it is found that: 1) the objective of achieving fast RoCoF LoM detection (i.e. the dependability requirement) is feasible with the assumed settings but the protection security may be compromised under certain fault scenarios; 2) in addition to active power, the reactive power plays an important role in the RoCoF-based LoM detection; and 3) natural frequency oscillations following the fault clearance can lead to the unwanted RoCoF operation. These factors will need to be considered during the LoM setting process to ensure the proper balance between LOM protection dependability and security
Standardization of power system protection settings using IEC 61850 for improved interoperability
No full textOne of the potential benefits of smart grid development is that data becomes more open and available for use by multiple applications. Many existing protection relays use proprietary formats for storing protection settings. This paper proposes to apply the IEC 61850 data model and System Configuration description Language (SCL), which are formally defined, to represent protection settings. Protection setting files in proprietary formats are parsed using rule-based reasoning, mapped to the IEC 61850 data model, and exported as SCL files. An important application of using SCL-based protection setting files is to achieve protection setting interoperability, which could bring multiple compelling benefits, such as significantly streamlining the IED configuration process and releasing utilities from being “locked in” to one particular vendor. For this purpose, this paper proposes a uniform configuration process for future IEDs. The challenges involved in the implementation of the proposed approach are discussed and possible solutions are presented
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