15th International Conference on Developments in Power System Protection (DPSP 2020)
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- Location: Liverpool, UK
- Conference date: 9-12 March 2020
- ISBN: 978-1-83953-277-1
- Conference number: CP771
- The following topics are dealt with: Protection of networks; Evolving technologies and future networks; Protection during black-start/network restoration; Protection and impact of converter dominated networks and low inertia systems; Plant/substation protection; Advances in communications for protection applications including Cyber security; and Protection implications of emerging technologies and future networks.
1 - 20 of 137 items found
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Validation of dynamic GB transmission system models with PMU data for hardware-in-the-loop studies
- Author(s): P. Imris ; M. Bradley ; G. Taylor ; Yun Li
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6 pp.
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Decarbonisation of the electrical power system in Great Britain (GB) has impacted the dynamic behaviour of the power system, not least due to the reduction in system inertia. Following disturbance events on the power system, Fast Frequency Phenomena (F2P) can be observed which may cause mal-operation of Loss-of-Mains (LoM) protection relays on distributed generation where the relays use Rate of Change of Frequency (RoCoF) or Vector Shift (VS) to detect loss of mains. The research presented in this paper aims to validate a full model of the GB transmission system using Phasor Measurement Unit (PMU) data from system events. The model is implemented in the DIgSILENT PowerFactory analysis software. Three types of F2P are compared in the period following the disturbance when LoM protection may be affected: simulation of electromagnetic (VS) phenomena shows some differences to actual PMU measurements, but the electromechanical and mechanical phenomena (affecting RoCoF) are in good agreement. The distribution of inter-area oscillation frequency modes following the disturbances are also closely represented in the model. Based on these studies, it can be concluded that the model is suitable for F2P studies using Hardware-in-the-Loop simulation with real LoM protection relays.
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Operational testing of virtual and physical IEDs using GOOSE for protection application
- Author(s): S. Ansari ; P. Das ; D. Weller ; P. Raussi ; D. Babazadeh
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6 pp.
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The integration of Operation Technology such as Intelligent Electronic Devices (IEDs) brings added challenges for testing and operation of complex interconnected protection systems. The hardware limitations of IEDs, such as integration in existing infrastructure and reduced run time control, limits engineers and researchers to test complex protection and automation scenarios. Virtualization of these technologies, allows seamless integration of software units into existing systems, which can be scaled up for large scale system testing. In this paper, the operation of virtual IEDs has been validated with that of physical IEDs. Two separate test platforms are used; one for the physical IED infrastructure and the other for virtual IED (vIED) infrastructure. A use case for overcurrent feeder protection using GOOSE communication has been demonstrated. The performance of circuit breaker tripping and GOOSE communication has been demonstrated and compared for both the test platforms. The vIED operational ability is validated and key insights for future work are given.
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Renewable Integration using IEC 61850 Enabled Smart Distribution IEDs with Customizable Functions
- Author(s): K. Venkataraman ; M. Kanabar ; H. Bhatia
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6 pp.
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High penetration of renewable resources into traditional Medium Voltage (MV) or secondary distribution grid may impose severe challenges due to bidirectional power flow, low-inertia generation interconnections to weak grid, maintaining power quality, etc. In addition, secondary distribution grid would also require special attention due to aging of the existing infrastructure; lack of automation of existing grid assets; need for remotely managed devices; and regulated reliability indices to maintain grid supply. The Grid operators are formulating guidelines for interconnection and operation of distributed generation in parallel to the Medium Voltage (MV) network. This requires specific capabilities in the Smart Distribution IEDs. To alleviate above challenges, without complete revamp of an existing distribution grid infrastructure, this paper proposes how the smart distribution Intelligent Electronic Devices (IEDs) can be applied to optimize the Capital Expenditure (CAPEX) for a distribution utility.
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Phasor-based and time-domain transmission line protection considering wind power integration
- Author(s): J.S. Costa ; R.T. Toledo ; L.A. Gama ; T.R. Honorato ; F.V. Lopes ; P.S. Pereira ; G.S. Salge ; M.J.B.B. Davi
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6 pp.
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The increasing integration of converter-interfaced wind power plants into the existing power systems has been a challenge for protection and monitoring functions. As a result, studies on protection performance considering this type of generation have been a topic of great interest to the industry. In this way, this paper evaluates the performance of phasor-based and time-domain protection functions available in real micro-processed protective devices when applied to a 500 kV/60 Hz transmission line that interconnects a wind power generation plant to a traditional power system. The test system was modelled and simulated by means of the Power System Simulator (PS Simul) software, through which different fault scenarios were evaluated by varying parameters such as fault location, fault resistance and inception angle. The obtained results highlight differences in evaluated protective relays' performances when applied to both line terminals, revealing the impact of converter-interfaced wind power plants on the relays' reliability and operation times.
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The behaviour of virtual synchronous machine (VSM) based converters in front of non-saturable faults
- Author(s): Zhenkun Yang ; A. Egea-Àlvarez ; A. Dysko
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6 pp.
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Power converter penetration has increased substantially in the last 20 years bringing new challenges from the system protection perspective. The power network is undergoing a major transformation as the major part of new installed power comes from nonsynchronous sources such as wind or solar. These changes might lead to malfunction of the conventional protection schemes such as overcurrent protection or distance protection relays. At the same time, the reduction of the system inertia might cause the tripping of the Loss of Main protection due to a very aggressive Rate of Change of Frequency. To enhance the grid voltage source characteristic and mitigate the loss of inertia, a new set of converter controllers known as Grid forming Converter or Virtual Synchronous Machine has been suggested in recent years. The performance of VSM could provide a potential advantage compared to traditional power converter controllers when a large frequency deviation occurs helping to keep the system stable. This article quantifies and compares the performance of different converter control algorithms including Current Vector Control, Virtual Synchronous Machine and Power Synchronisation Control in front of different frequency events.
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Integration of new customer tertiary connections to existing transformer protection and control arrangements and associated new solutions
- Author(s): M.M. Osborne ; S. Dhakshinamurthi ; N. Tart
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6 pp.
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The Government has set a target for the UK to be a net zero carbon society by 2050. This is a massive National challenge, and the Electricity sector will have a major role in helping to deliver this ambition. A lot of the new connecting capacity will be smaller dispersed modules, typically below 50MW. These will include renewable generation, demand (electric vehicle charging, space heating) and grid balancing solutions. The provision of fast, secure network access for these new services is the best way for the Electricity networks to meet this demand. National Grid Electricity Transmission (NGET) has developed a new bay solution which utilises the existing 13kV tertiary winding on its Super-Grid Transformers (SGT) via a step-up transformer to provide a supply connection at 33kV. The paper introduces this new design and the challenges which must be overcome to deliver the application. The focus will be on the protection and control for the new transformer tertiary connection arrangement, highlighting the interfacing challenges with the existing protection and control systems. It also explores the considerations for the longer-term asset management and future applications associated with this type of connection.
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Secure and dependable protection relay behaviour in extremely high loaded transmission systems
- Author(s): J. Schindler ; J. Prommetta ; J. Jäger
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6 pp.
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Current developments in the electricity grids demand for an optimal utilization of existing grids. To make this possible, more measurement, communication, computing, active control equipment and automation needs to be implemented into the grids. As a consequence, this entails extremely high loaded transmission corridors. While such operation is on the one hand a big challenge from a grid control perspective, the protection systems too need to behave securely and dependably under such circumstances. This work discusses the various ways in which conventional protection systems are influenced by extreme loading using the example of distance protection. After that, numerous existing solution approaches to these challenges are presented. The described methods can be categorized in those that directly improve the behaviour of the relays and those that concern the protection congestion consideration in the control centres. They range from small adjustments like changed safety factors to adaptive techniques to avoid constant worst-case assumptions to modified measurement algorithms and completely new designed fault detection and localization approaches. It is highly probable that the field of secure and dependable protection systems in extremely high loaded grids will be of increasing importance in the future.
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Cybersecurity based on IEC 62351 and IEC 62443 for IEC 61850 systems
- Author(s): D. Dolezilek ; D. Gammel ; W. Fernandes
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6 pp.
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The word “cyber,” originating from the Greek word meaning “skilled steering or guidance,” has taken on the modern meaning of using digital communications within and among intelligent devices to perform information gathering and commanded control. Information technology (IT) systems include networked communications among computers, business systems, and the internet. Operational technology (OT) systems include networked communications among industrial control system (ICS) devices performing automatic safety, operational, and monitoring processes. In this paper, established ICS methods and standards are used to design defense-in-depth cybersecurity methods for digital communications within an energy control system (ECS) communications network. The ECS communications architecture is a mission-critical ICS and is divided into multiple levels with unique requirements and features from the process up through the station and finally to the control center. Using these levels, it is possible to identify interacting cyber defense technologies, the levels at which they should be deployed, and which devices they belong to (IEC 62443 Part 3) instead of the arbitrary defense-in-breadth strategy of requesting that every device include every cyber defense technology (IEC 62443 Part 4).
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Testing of Protection in a Digital Substation Protection Automation and Control System (SPACS)
- Author(s): R.S.J. Loken and A. Apostolov
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6 pp.
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This paper will be based on the work of CIGRE WG B5.53 [1] and it will cover the testing of the complete digital functional chain, including the use of process bus for the transmission of the analogue values and station bus for the transmission of trip orders and other signals for substation protection, automation and control systems (SPACS). The focus will be on testing of protection in a fully digital IEC 61850 [2] substations and equipment. The increasing levels of functional integration result in the development of many multifunctional Intelligent Electronic Device (IEDs) that require interfaces with multiple primary devices. Testing of SPACS at its most basic is the creation of simulated inputs to a function or device to verify the operation and performance expectations taking into account the type of test and the traffic on the communication network. When testing a fully digital substation, it is necessary to create simulated data as inputs to specific Logical Nodes (LN) or Logical Devices (LD). In order to publish simulated data for testing, it is necessary to use a data message which the SPACS communication network can accept and transmit.
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Design and commissioning of a secure substation network architecture
- Author(s): A. Klien ; Y. Gosteli ; S. Mattmann
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5 pp.
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Utilities and cyber security auditors are increasingly considering not only the control centre as critical attack vector, but also substations as potential entry points for cyber attacks. Important risk factors are the processes, how the commissioning of the protection and control systems are realized and how remote maintenance access is implemented. Therefore, the architecture of the protection and control system must be reviewed for security. To achieve this, the Swiss generation and distribution utility Centralschweizer Kraftwerke AG (CKW) started a project in 2016/2017 to develop a new reference architecture for their secondary systems. Their design addresses these attack vectors with countermeasures, while still offering a sensible balance between maintainability and security. The design includes multiple levels of security including multiple firewall layers. Additionally, an Intrusion Detection System (IDS) is applied. Selecting a suitable IDS for substations proved out to be challenging, as many IDS don't support the requirements of substation networks. This paper starts with an enumeration of the most important attack vectors on substations, followed by a description of the security architecture implemented for the first time in a new greenfield 110kV substation project by CKW. The paper concludes with the experiences in selecting a suitable IDS for substations and the lessons learned in the factory acceptance test of this project.
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Overcurrent relays coordination optimisation methods in distribution systems for microgrids: a review
- Author(s): S. Abeid and Yanting Hu
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8 pp.
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Electric power networks connected with multiple distributed generations (microgrids) require adequate protection coordination. In this paper, the overcurrent relay coordination concept in distribution system has been presented with details. In this available literature, the previous works on optimisation methods utilised for the coordination of over current relays; classification has been made based on the optimisation techniques, non-standard characteristics, new constraints that have been proposed for optimal coordination and dual setting protection schemes. Then a comprehensive review has been done on optimisation techniques including the conventional methods, heuristic and hybrid methods and the relevant issues have been addressed.
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An Active Protection Scheme for Islanded Microgrids
- Author(s): M.A.U. Khan ; Qiteng Hong ; A. Dyśko ; C. Booth
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6 pp.
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The paper proposes a relatively simple active protection strategy incorporating controllers of the inverter for islanded microgrids dominated by inverter based distributed generators (IBDGs) that can overcome well-understood shortcomings in traditional overcurrent protection schemes applied to weak islanded systems. During a fault, the scheme identifies that a fault has occurred and instructs each IBDG in the islanded microgrid to inject specific harmonic components in conjunction with fault current; relays in the network can subsequently detect the presence and location of the fault based on the injected combination of harmonic components. The coordination of relays is achieved through definite time settings, hence communication between the protective relays is not required to operate the scheme. Furthermore, the scheme categorises the protective relays into two groups to isolate the faulty section effectively to cater for bidirectional fault current flow - this is described fully in the paper. The paper presents the structure of the proposed protection scheme along with injection strategy through the control of IBDGs. Different fault scenarios are presented using a realistic microgrid model so that effectiveness of the proposed scheme can be demonstrated in terms of detecting, identifying the faulted section and isolating the fault to ensure dependability, security and selectivity of the microgrid protection scheme.
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Current Restrained Undervoltage Protection Scheme of Converter Dominated Microgrids
- Author(s): R. Mohanty ; Peiyuan Chen ; Le Anh Tuan
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6 pp.
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This paper presents a current restrained undervoltage protection method for converter dominated microgrids. Current magnitude based conventional protection fails to detect a fault in converter dominated microgrid due to current limiting capability of converters. Fault detection becomes more complicated during islanded operation of such a microgrid. This is because, the current does not exceed the rated value and remains below pickup setting of overcurrent relay during the fault. One alternative is to use undervoltage relay. However, this may not function correctly in the case of a fault at the end of a long cable or a high impedance fault. The current restrained undervoltage based proposed method does not rely on communication and the selectivity can be achieved by using a blinder in a VI-plane. Subsequently, the operating time of the relay is calculated using the index obtained from change in current and voltage inside the blinder. The performance of the proposed method is tested at different fault types and locations with different fault resistance in a converter dominated microgrid.
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A method for predictive out-of-step tripping based on synchrophasors
- Author(s): T.D. Duong ; S. D'Arco ; A. Holdyk
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6 pp.
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This paper presents a method for predictive out-of-step (OOS) tripping based on synchrophasors. The OOS condition is predicted based on information of the ongoing power oscillation, where the input signal can be either the phase angle between two nodes in the power grid or the current magnitude of a line. The proposed algorithm first detects power swing by comparing the oscillation magnitude with a set threshold. Once a power swing is detected, a damping coefficient associated to the power oscillation is estimated to assess its stability. The oscillation is predicted unstable and eventually will lead to OOS condition when both the damping coefficient and the input signal are larger than set thresholds. The tuning of these thresholds is relatively simple and straightforward. Results from simulations in the Kundur system and the Nordic 44 model demonstrate that the proposed algorithm is able to correctly predict coming OOS conditions from the analysis of power swings in the power grid.
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A novel protection scheme for inverter-dominated microgrid
- Author(s): Di Liu ; D. Tzelepis ; A. Dyśko ; C. Booth
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6 pp.
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Protecting an inverter-dominated microgrid is challenging for the traditional overcurrent protection scheme owing to the suppressed fault current from the inverter interfaced DGs (IIDGs). In this paper, a protection scheme based on the Discrete Wavelet Transform is developed in MATLAB/SIMULINK to detect the faults in the microgrid. The input voltage of the proposed scheme is first transformed into dq0 frame using the Park Transform. A filtering system based on the wavelet denoising approach is then implemented to reduce the sampling frequency and reject the switching noise generated by the inverters in the microgrid. The performance of the proposed scheme is evaluated in transient simulation by systematically applying different types of faults, including varied fault positions and impedances. Additionally, a high impedance arcing fault model is implemented to test the proposed protection scheme under nonlinear fault impedance conditions.
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Frequency domain analysis of HVDC grid non-unit protection
- Author(s): V. Psaras ; G.P. Adam ; G. Burt
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6 pp.
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Owing to the fact that the propagated travelling waves following a DC fault in HVDC grids consist of a wide range of frequencies, frequency domain analysis provides a useful means to assess DC protection schemes, including non-unit protection schemes. Non-unit protection uses series inductors at key nodes to distinguish between internal and external faults, exploiting the fact that these inductors present high impedance at high frequencies. Consequently the transient voltage frequency response in each fault case is recognisably different. On this basis, the investigation in the frequency domain can reveal significant information for protection design purposes. Towards this aim, the transient voltage at the relay location is meticulously represented in the frequency domain by taking into account the transmission medium length and geometry, the number of other attached feeders to the same bus, the converter parameters, the inductive termination, the fault resistance, and the travelling wave behaviour of DC faults. By performing a sensitivity analysis on these parameters, a deeper understanding of their impact on HVDC non-unit protection is obtained. In addition, the factors that can be adjusted to extend the reach of the protection systems are revealed and a generic approach for analytically calculating the protection threshold is developed.
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On evaluating a time-domain distance element of a real relay for double-circuit transmission line protection
- Author(s): T.R. Honorato ; V.R. Serpa ; J.P.G. Ribeiro ; E.A. Custódio ; K.M. Silva ; F.V. Lopes
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6 pp.
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This paper presents an evaluation for a time-domain distance element, presented in a commercially available relay, for double-circuit transmission line protection. Although it is widely known that traditional phasor-based distance elements are significantly affected by the zero-sequence coupling present in double-circuit transmission lines, the amount of influence in the time-domain element still unknown. As a result, the analysis presented in this paper propose to clarify the effect of zero-sequence coupling on time-domain elements. The evaluation was carried out by testing three different scenarios of network equivalent, since it affects the zero-sequence coupling since it governs the current flowing on the healthy circuit. Within each scenario, a variation of fault distance in 1% increments is performed, resulting in a total of 297 events. Overall, the time-domain distance element has demonstrated less influence on underreach and similar in overreach when compared to the traditional distance element, besides being more consistent and faster. However, special considerations are necessary to guarantee secure operation.
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Dealing with uncertainties in non-homogeneous transmission line electrical parameters during traveling wave-based fault location procedures
- Author(s): F.V. Lopes ; E.J.S.L. Junior ; F.B. Costa
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6 pp.
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This paper presents a methodology to deal with uncertainties in electrical parameters of multi-section non-homogeneous lines (NHLs) during traveling wave (TW)-based fault location procedures. Required functions to detect fault-induced TWs, to identify the faulted section and to estimate fault search fields are firstly described and then, their step-by-step are demonstrated by means of Alternative Transients Program (ATP) simulations of faults on a four-section 380 kV/50 Hz NHL. A closed-form fault location solution is used to analyse the test system, taking into account settings computed by means of line parameters that present some level of uncertainty. Fault features and applied settings are varied in order to demonstrate the procedures of interest, highlighting the influence of NHL uncertainties on TW-based fault location procedures. The obtained results reveal the presented methodology is reliable and able to properly estimate the faulted section, as well as to calculate reliable fault search fields, even when realistic inaccuracies in line parameters are considered.
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An undervoltage protection function for distributed generators complying with the low-voltage-ride-through requirements
- Author(s): A.M. Tsimtsios ; A. Patsidis ; V.C. Nikolaidis
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6 pp.
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This paper implements an undervoltage protection function for distributed generators connected to distribution systems, which complies with the recent low-voltage-ride-through requirements. This function takes account of the adopted low-voltage-ride-through curve, as well as the relevant requirements concerning consecutive low-voltage disturbances. In this regard, it can preserve low-voltage-ride through operation, concurrently preventing an excessive network energization by the generator. The designed function is described in detail, while, it is modelled using MATLAB/Simulink. Furthermore, it is tested by simulating different kinds of consecutive low-voltage disturbance events.
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Challenges for earth-fault protections due to extensive use of cables in the grid
- Author(s): Z. Gajić
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5 pp.
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Capacitive zero-sequence currents do exist in any power system during an earth-fault regardless network grounding principles. However, existence of these currents is typically ignored in traditional protection practice. In many countries some type of high-impedance grounding is used which limits the earth-fault current to a certain level. Increased use of cables in medium voltage distribution grids and high voltage sub-transmission grids can also significantly raise the capacitive earth fault currents, which in combination with the used grounding principle in the power network can pose a problem for proper operation of some relays.
