Fig 15 - uploaded by Ata Mokhberdoran
Content may be subject to copyright.
Source publication
Protection issue is identified as the main drawback of emerging multi-terminal HVDC grids. Multi-terminal HVDC grid demands fast short circuit fault current interruption. Fast DC circuit breakers as a promising solution can be implemented as either bidirectional or unidirectional devices. In addition to less implementation cost, the unidirectional...
Citations
... The HB-MMCs are interconnected by five cables with 100 mH inductors and circuit breakers at their ends; this way, each cable comprises an independent protection zone. An inductor size of 100 mH is widely used in the literature when local-measurement-based algorithms are employed in order to accurately delimit the protection zones, e.g., [14,[18][19][20][23][24][25][26][27][28]. ...
HVDC grids demand the fast and reliable operation of the protection system. The failure of any protection element should initialize a backup protection almost immediately in order to assure the system’s stability. This paper proposes a novel backup strategy that covers the failure of the primary protection including the malfunctioning of the HVDC circuit breaker. Only local voltage measurements are employed in the proposed backup protection and the voltage derivative is calculated at both sides of the limiting inductor. Consequently, the speed and reliability of the protection system are enhanced, since no communication channel is needed. This paper contains a thorough specification of the proposed protection strategy. This strategy is validated in a four-terminal HVDC grid with various fault case scenarios, including high-resistance fault cases. The operation of the backup protection is reliable and remarkably fast.
... In selective fault clearing strategy, only circuit breakers associated with the faulted line is used to interrupt fault current but in non-selective fault clearing strategy, fault current is interrupted by combined actions of multiple components such as the converters with the facilities of fault interrupting and limiting capability. Because of too much complexity in non-selective fault clearing strategy and fear of increasing capital expense of converter stations, it is practically not feasible to apply over large power systems [23,24,[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59]. ...
The facilitation of bulk power transmission and non-synchronized interconnection of alternating current (AC) grids convince engineers and researchers to explore high voltage direct current (HVDC) transmission system in a comprehensive way. This exploration focuses on control and protection of HVDC transmission system. Fault estimation is a core component of protection of HVDC transmission system. This is because of sudden built up of direct current (DC) fault. In this research, DC fault is estimated in multi terminal HVDC transmission system based on restricted Boltzmann machine. Restricted Boltzmann machine is a generative stochastic artificial neural network in which learning of probability distribution is conducted over the set of inputs. Three terminal HVDC transmission system is simulated under normal and faulty conditions to analyze variations in electrical parameters. These variations serve as learning parameters of restricted Boltzmann machine. Contrastive divergence algorithm is developed to train restricted Boltzmann machine. It is an approximate maximum likelihood learning algorithm in which gradient of difference of divergences is followed. It is found that fault is estimated with the testing of variations in minimum time steps. Simulation environment is built in Matlab/Simulink.
... Overcurrent algorithms have been extensively used in the literature. Thus, this algorithm is employed for protecting a radial MT system in [23] and a four-terminal symmetric monopole VSC based grid in [24]. In both cases, unidirectional HVDC circuit breakers (CB) are used. ...
One of the most important challenges of developing multi-terminal (MT) high voltage direct current (HVDC) grids is the system performance under fault conditions. It must be highlighted that the operating time of the protection system needs to be shorter than a few milliseconds. Due to this restrictive requirement of speed, local measurement based algorithms are mostly used as primary protection since they present an appropriate operation speed. This paper focuses on the analysis of local measurement based algorithms, specifically overcurrent, undervoltage, rate-of-change-of-current, and rate-of-change-of-voltage algorithms. A review of these fault detection algorithms is presented. Furthermore, these algorithms are applied to a multi-terminal grid, where the influence of fault location and fault resistance is assessed. Then, their performances are compared in terms of detection speed and maximum current interrupted by the HVDC circuit breakers. This analysis aims to enhance the protection systems by facilitating the selection of the most suitable algorithm for primary or backup protection systems. In addition, two new fault type identification algorithms based on the rate-of-change-of-voltage and rate-of-change-of-current are proposed and analyzed. The paper finally includes a comparison between the previously reviewed local measurement based algorithms found in the literature and the simulation results of the present work.
... DC lines are less expense of DC terminal gear is high when contrasted with AC terminal links (appeared in the diagram underneath) [10][11][12][13][14][15]. In this manner, the underlying expense is high in HVDC transmission framework, and it is low in the AC framework. ...
This paper is to ponder the use of Neural systems for shortcoming discovery and area in HVDC framework. The proposed Neural system learns examples and relationship on transient information. The Back-propagation algorithm has the ability to match map complex and nonlinear input - output behavior. A MATLAB model was created for the 500kv,1000MW,12 pulse-based converter-based distribution system and various fault events were simulated. The limitations of AC over long transmission lines has led to the use of DC for bulk transmission over long distances. Fault condition like rectifier fault, inverter faults and transmission line faults are discussed in this paper.
... Although at the moment, power electronic DCCBs are limited to low voltage DC implementations, they may become economically viable at high voltages as the losses of power electronic devices decrease in the future [12]. In recent years, innovative breaker topologies or control methods have been proposed focusing on capability enhancement, cost reduction or added current flow control capability, e.g., unidirectional or multi-port circuit breakers [13][14][15][16]. ...
... Other functions such as integrated current flow control and DCCBs with unidirectional fault current interruption have also been proposed in the literature [15,16]. However, they are not considered in this paper as the focus is on the functions related to fault clearing with the highest selectivity. ...
DC circuit breakers (DCCBs) are one of the key components to facilitate large meshed HVDC grids. Driven by the needs for achieving high speed, low loss and low cost, various DCCB technologies have been proposed for HVDC applications. Unlike AC circuit breakers (ACCBs), some DCCBs provide a variety of functions, such as proactive opening or fault current limiting (FCL), mainly attributed to the high controllability of the power electronic switches used in such DCCBs. To enable these functions, the intelligent electronic devices (IEDs) are expected to provide signals steering these functions in addition to a trip command. Interoperability between IEDs and DCCBs from different vendors is considered feasible, but expected to be more complex than their AC counterparts, due to the different functions provided by various DCCB technologies. It is therefore crucial to understand which of the functions are essential to fulfil the requirements imposed in HVDC grid protection, and to standardise the interfaces between the IEDs and DCCBs to achieve multivendor interoperability between IEDs and DCCBs provided by different vendors.
This paper first classifies the DCCB functions into minimally required and auxiliary ones based on reviewing the existing literature. Then, standardised interfaces between the IEDs and DCCBs are proposed to enable both types of DCCB functions. An example of such IED is implemented in PSCAD/EMTDC to demonstrate that the proposed interfaces are adequate to enable both minimally required and auxiliary functions using a four-terminal test system. Auxiliary functions of hybrid DCCBs, such as proactive opening, fault current limiting, fast reclosing and reopening, breaker failure internal detection and repeated O-C-O operation are demonstrated by simulations.
... Given that the cost for fully protecting an HVDC grid will be significant as multiple DCCBs are needed, it is essential to restrict the use of controllable switches to make dc protection more cost-effective. The use of unidirectional HCBs can reduce the number of controllable semiconductors by half at the expense of only being capable of interrupting currents in the forward direction [23], [24]. An H-bridge based HCB can relieve this shortcoming as it can block current bidirectionally with similar number of controllable switches as a unidirectional HCB [25]. ...
... , is only reached at the occurrence of a bus fault. Using the analysis carried out in Section III-A for the HCBs, Equation (24) shows that if HCBs are used, the number of IGBTs in the MBs will increase when more nodes are connected, although the size of their LCSs is smaller compared to those of a BT-ICB. ...
The inclusion of a large number of controllable semiconductor devices in conventional hybrid dc circuit breakers (HCBs) may significantly increase the cost of an HVDC grid protection scheme. In an attempt to reduce this cost, this paper proposes the use of two novel topologies of bridge-type integrated HCBs (BT-ICBs). The two configurations are examined in detail, their operation sequences are established and a detailed parametric analysis is conducted. The total number of controllable semiconductor devices in a BT-ICB is assessed with the aid of selectivity studies and a comparison is made when conventional HCB and other ICB topologies are considered. It is shown that the proposed configurations employ 50 to more than 70% less controllable devices compared to conventional HCBs. The proposed BT-ICB topologies are tested in PSCAD/EMTDC using a four-terminal HVDC grid. Simulation results demonstrate the capability and effectiveness of the proposed solutions to isolate different types of dc faults at either a dc line, a converter terminal or a dc bus.
... The main concern when implementing MTDC systems is still the limitation of DC circuit breakers as the fault current rises rapidly and does not cross zero. Due this fact, it is a hard task to isolate only the faulted part of the system [2], [23]. In an attempt to achieve an accuracy and fast protection method, this work presents and compares three different ANN-based methods for fault detection and location in MTDC systems. ...
... Several protection strategies have been proposed for MT-HVDC and M-HVDC grids [14,1,[18][19][20]. However, fast DC circuit breakers (DCCB) are to be most promising solution for M-HVDC grid. ...
... In a system protected by a fully selective protection scheme, every line is equipped with one DCCB at each end. The converter may be protected by either a DCCB at its DC side or an AC circuit breaker at its AC side [18]. A possible arrangement of DCCBs in a fully protected M-HVDC grid is shown in Fig. 3(a). ...
... Negative currents In this study, the DCCB is modeled as an ideal switch in series with an inductor, which interrupts the current independently of its magnitude after an operation delay defined by T cb upon receiving a trip command [18]. Note that in this study no trip signal is applied to the DCCBs in order to study the fault current behavior. ...
Current flow controllers (CFCs) can remove grid bottlenecks or extend grid operation area by changing amount of power flowing through DC transmission lines. This study focuses on behavior of interline H-bridge CFC in a DC grid in fault condition. In addition to the CFC circuit level fault studies, non-linear and linearized simplified models are developed for system level analysis. The analysis and fault study shows that the interline H-bridge CFC cannot survive during DC transmission line and bus faults due to an overvoltage occurring in its capacitor. Further investigation figures out that this overvoltage cannot be avoided even in presence of fast HVDC circuit breakers. Hence, an improved control system together with circuit level modifications are proposed to improve the CFC post-fault operation and to retain its components from possible damages.
... DC circuit breakers topologies applications in MT-HVDC for clearing the faults in addition to the network recovery strategies after clearing the faults using AC circuit breakers were newly proposed. However, they adopted traditional fault identification methods such as pre-fault and after fault measurements and measuring the voltage drop across a series inductance [11][12][13][14][15][16]. The present authors proposed a travelling wave-based technique applicable for any fault type, for discovering the fault location and type in MT-HVDC systems [17]. ...
The most convenient solution to link faraway significant renewable energy sources (RESs) is the voltage-source converter multi-terminal high-voltage DC systems (MT-HVDC). However, to maintain system stability and continuity of supply, a rigid and fast fault locating technique is required. This study proposes a novel inherent travelling waves based short-circuit DC fault identifier, which accurately identifies both of the fault location and faulty pole in multiple numbers of cables in MT-HVDC system using a single current sensor. Both of a discrete wavelet examiner and a fuzzy-neural pattern recogniser precisely spot the faulty line and fault location based on the mutual effects of short-circuit initiated travelling waves between lines belonging to the same loop. A software toolbox is structured to illustrate the adequacy of the proposed artificial intelligence technique. This method is valuable to MT-HVDC administration centres, particularly those concerned with long-distance RES.
... In [25], this principle is investigated for the protection of MTDC cables using incident waves which are non-dependent of boundary conditions in the protection terminals. In [26], a protection method based on unidirectional hybrid circuit breakers (UHCB) using DC bus logic is presented for MTDC grids. The proposed method consists of two different unidirectional strategies based on local communication based and remote overcurrent fault detection, and the impacts of using UHCB and the proposed methods on converters, DCCB, surge arrester energy ratings and CB current ratings are investigated. ...
