17 results found
PIpelzadeh Y, Moreno R, Chaudhuri B, et al., 2017, Corrective control with transient assistive measures: value assessment for Great Britain transmission system, IEEE Transactions on Power Systems, Vol: 32, Pages: 1638-1650, ISSN: 0885-8950
In this paper, the efficacy and value of using corrective control supported by transient assistive measures (TAM) is quantified in terms of the cost savings due to less constrained operation of the system. The example TAM is a rapid modulation of the power order of the high-voltage direct current (HVDC) links in the system so as to improve transient stability during corrective control. A sequential approach is used for the offline value assessment: a security constrained economic dispatch (SCED) module (master problem) determines the optimal generation dispatch, HVDC settings, and the corrective control actions to be used post-fault (generation and demand curtailed) so as to minimize the operational costs while ensuring static security. The transient stability module (slave problem) assesses the dynamic stability for the operating condition set by the SCED and, if needed, applies appropriate TAM to maintain the system transiently stable. If this is not possible, the master module uses a tighter set of security constraints to update the dispatch and other settings until the system can be stabilized. A case-study on the Great Britain system is used to demonstrate that corrective control actions supported by TAM facilitate significantly higher pre-fault power transfers whilst maintaining N-2 security.
Pipelzadeh Y, Ray Chaudhuri N, Chaudhuri B, et al., 2016, Coordinated control of offshore wind farm and onshore HVDC converter for effective power oscillation damping, IEEE Transactions on Power Systems, Vol: 32, Pages: 1860-1872, ISSN: 1558-0679
Damping contribution from wind farms (WFs) islikely to become a mandatory requirement as part of the gridcodes. For remote offshore WFs, connected through a voltagesource converter (VSC)-based direct current (DC) link, the mostconvenient option for the onshore transmission system operator(TSO) is to modulate the reactive power at the onshore VSCwithin their own jurisdiction. In this paper, we show thatsupplementary control through the onshore VSC alone, althoughattractive for TSOs, could result in unacceptable voltage variationsin the onshore power grid. On the other hand, modulation ofactive power output of the wind turbine generators (WTG) aloneturns out to be inadequate due to the limited overload capabilityof the WTGs and the on- and offshore VSCs. Coordinated controlover both onshore VSC and aggregated WF output overcomes theabove limitations and is shown to be effective for power oscillationdamping. A homotopy approach is used to design the coordinatedcontroller, which can be implemented locally (at offshore WF andonshore converter site) using a decentralized architecture. Casestudies on two test systems show that the proposed controlleryields similar system dynamic response as supplementary controlthrough the WF alone.
Goharrizi AY, Muthumuni D, Pipelzadeh Y, 2016, Modeling of Type-3 Wind Farm and Investigation of Fault Contribution in Power System, IEEE-Power-and-Energy-Society General Meeting (PESGM), Publisher: IEEE, ISSN: 1944-9925
Pipelzadeh Y, Chaudhuri B, Green T, 2015, Modelling and Dynamic Operation of the Zhoushan DC Grid: Worlds First Five-Terminal VSC-HVDC Project, International High Voltage Direct Current 2015 Conference, Publisher: IET, Pages: 87-95
This paper highlights the world’s first operational MTDC grid, namely the 5-terminal Zhoushan DC grid. The scheme went under operation in 2014. The topology and operation of the Zhoushan DC grid are demonstrated with recorded measurements obtained from the converter station, after being subjected to system disturbances. A generic modeling framework for the Zhoushan DC grid is developed inPSCAD/EMTDC. One particular concern is how the Zhoushan DC grid would react to DC side faults and the resulting power imbalance. Despite the completion of the Zhoushan MTDC grid, technological barriers such as the unavailability of fast protection systems, DC circuit breakers and highly efficient VSCs with DC side fault-clearing capabilities have all been bottlenecks at the time of commissioning, but are now under extensive research and development. The challenges and importance of DC grid protection are highlighted through case studies performed on the DC grid model in PSCAD/EMTDC.
Junyent-Ferre A, Pipelzadeh Y, Green TC, 2015, Blending HVDC-link energy storage and offshore wind turbine inertia for fast frequency response, IEEE Transactions on Sustainable Energy, Vol: 6, Pages: 1059-1066, ISSN: 1949-3029
This paper explores the benefits of combining the dc-link energy storage of a voltage source converter-based high-voltage dc (VSC-HVDC) link and the kinetic energy storage from wind turbines to facilitate in fast primary frequency control and system inertia to an ac network. Alongside physical and analytical justifications, a method is proposed which blends the energy stored in the HVDC link with the power control capabilities of the wind turbines to provide frequency response that is fast while not requiring excessive volume of capacitance nor demanding performance requirements on the wind turbines.
Pipelzadeh Y, Moreno Vieyra R, Chaudhuri B, et al., 2015, Role of Smart Grid Technology and Corrective Control in Enhancing Network Capacity Utilisation in Great Britain with HVDC links, CIGRE SYMPOSIUM, Publisher: CIGRE
A range of advanced, technically effective and economically efficient corrective (or postfault) actions has been proposed to release latent transmission network capacity of the existing system and thus reduce network congestion and accommodate increased connection of low-carbon generation. Although the increased use of corrective control that can manage post-fault transmission overloads has proven to be clearly beneficial from an economic perspective, there are concerns related to the consequent stability (angular and voltage) of transmission systems. In this context, this paper demonstrates various corrective control measures (that can be undertaken by Special Protection Schemes –SPS–) including rapid response of generation and demand against double line outages (N-2) under extremely high power transfer conditions. To demonstrate these benefits, case studies are carried out on a detailed (full) dynamic system model of the Great Britain (GB) transmission network in DIgSILENT, which includes the Western Line-Commutated Converter based High Voltage Direct Current (LCC-HVDC). The value of corrective control measures, based on generationand demand response accompanied by Transient Assistive Measures (TAM) such as rapid changes in DC power order to improve system stability is demonstrated. It is shown that such measures can significantly increase the power transfers through the England-Scotland inter-connector while maintaining N-2 security. Moreover, it is demonstrated that although a generation ramp up/down response is naturally slower than a step-change tripping action over generation and demand (tripping actions are preferred in SPS) and therefore more prone to transient instability problems, generation-only operational measures can be deployed to deal with double circuit (N-2) outages under extremely high power transfers, given that the right portfolio of TAM is deployed. Thus TAM can effectively enhance the set of correctivecontrol measures considered b
Spallarossa CE, Merlin MMC, Pipelzadeh Y, et al., 2015, Reduced Dynamic Model of a Modular Multilevel Converter in PowerFactory, IEEE 16th Workshop on Control and Modeling for Power Electronics (COMPEL), Publisher: IEEE, ISSN: 2151-0997
Pipelzadch Y, Chaudhuri B, Green TC, et al., 2015, Role of Western HVDC Link in Stability of Future Great Britain (GB) Transmission System, General Meeting of the IEEE-Power-and-Energy-Society, Publisher: IEEE, ISSN: 1944-9925
Spallarossa CE, Pipelzadeh Y, Green TC, 2013, Influence of Frequency-Droop Supplementary Control on Disturbance Propagation through VSC HVDC Links, General Meeting of the IEEE-Power-and-Energy-Society (PES), Publisher: IEEE, ISSN: 1944-9925
Pipelzadeh Y, Chaudhuri NR, Chaudhuri B, et al., 2012, System stability improvement through optimal control allocation in voltage source converter-based high-voltage direct current links, IET GENERATION TRANSMISSION & DISTRIBUTION, Vol: 6, Pages: 811-821, ISSN: 1751-8687
Pipelzadeh Y, Chaudhuri B, Green TC, 2012, Inertial Response from Remote Offshore WindFarms Connected Through VSC-HVDC Links: ACommunication-less Scheme, IEEE Power and Energy Society General Meeting 2012
A communication-less scheme that allows remoteoffshore wind farms connected through HVDC links to participatein primary frequency control and contribute to systeminertia is discussed in this paper. As a HVDC link decouples theoffshore system from the onshore side, real-time communicationof onshore frequency is normally required for the primaryfrequency control loop of the wind farms. Dependance on remotecommunication which could be unreliable at times is a problem.To obviate the need for communication, appropriate droopcontrol on the offshore and onshore converters is used in thispaper to translate the variation in onshore frequency to anequivalent variation on the offshore end. Thus the need for communicatingonshore frequency to the offshore side is mitigatedwhich ensures reliable operation. Such a communication-lessscheme is compared against the conventional approach involvingremote communication of onshore grid frequency to the windfarm site. Along side physical and analytical justification, a casestudy is presented to demonstrate that the communication-lessscheme performs similar to the conventional one in terms ofreducing grid frequency variations.
Piplezadeh Y, Chaudhuri B, Green TC, 2012, Control Coordination Within a VSC-HVDC Link for Power Oscillation Damping: A Robust Decentralized Approach Using Homotopy, IEEE Transactions on Control Systems Technology
Power oscillations can be damped effectivelythrough modulation of both active and reactive power of a voltage source converter based high voltage direct current link. The challenge, however, is how to coordinate the control action properly at the two ends of the link without using a centralised control scheme, which requires fast communication of control signals to remote actuator (converters) sites. A full centralised controller may result in a closed-loop performance worse than that of an open loop in case of a communication loss of feedback signal(s). Alternatively, with a block-diagonal control structure, the individual control loops are decoupled from each other, which is not only easier to implement in a decentralized way, but also shown to guarantee a certain level of performance. Here, the concept of homotopy is applied to obtain a single block-diagonal controller from a set of full controllers, individually designed to ensure specified closed-loop performance for a set of operating conditions. Simulation studies in DIgSILENT PowerFactory are carried out on two test systems to demonstrate both the robustness and control coordination in a decentralised framework.
Pipelzadeh Y, Chaudhuri B, Green TC, 2011, The Impact of Significant Wind Penetration and HVDC Upgrades on the Stability of Future Grids: A Case Study on the Australian Power System, CIGRE International Symposium 2011
Wind power has been the fastest growing energy generation sector worldwide in recent years. Large on- and off-shore wind farms have a considerable impact on system security and stable system operation. Therefore its influence on the dynamic stability of the system must be addressed. For turbines above 1MW, doubly-fed induction generators (DFIG) are the most widely used concept. However in many countries such as U.K and Germany, full-rated converter (FRC) have also gained vast amount of market penetration.To address this, the paper presents studies performed in DIgSILENT PowerFactory aimed at ascertaining the impact that DFIG and FRC have on the oscillation modes of the power system. The feasibility, advantage and disadvantages of various options are discussed.Wind generators can be connected to existing power transmission networks spanning over long distances and ultimately causing interaction between wind-farms and transmission systems. The benefit of utilising HVDC (classical and/or Voltage- source) within an ac network for transporting large amounts of wind power to remote load locations is studied.Wind farms consist of large number of generators of relatively small size. Both types of variable speed wind generators (DFIG and FRC) have been modelled in detail in PowerFactory DIgSILENT. Model aggregation techniques are applied to reduce computation time. Different control strategies for VSC-HVDC and “classical” Thyristor-based HVDC links are presented and analyzed via network simulation. A case study is presented based on the equivalent SE Australian power system, an IEEE benchmark system for dynamic studies, with appropriate reinforcements introduced to accommodate wind generation and HVDC transmission systems.This paper is focused on the small-signal stability issues and analyses the impact of various aspects like generator technology, hybrid AC/HVDC transmission for getting a thorough understanding about the impact of these on the overall system sta
Pipelzadeh Y, Chaudhuri B, Green TC, 2011, Coordinated Damping Control Through MultipleHVDC Systems: A Decentralized Approach, IEEE Power and Energy Society General Meeting 2011
The role of multiple HVDC links - both CSC and VSC - in improving the AC system dynamic performance is presented here. An Australian equivalent system with three critical interareamodes is considered to illustrate the case study on DIgSILENT PowerFactory. Subspace-based multi-input-multi-output(MIMO) system identification is used to estimate and validatelinearized state-space models through pseudo random binary sequence (PRBS) probing in DIgSILENT PowerFactory. Choice of appropriate input-output combinations is done through modalresidue analysis taking note of not only the magnitudes but also the phase angles. The decentralized control design is posed as an optimization problem and solved using an evolutionary technique. The results are validated through linear analysis andnon linear simulation in DIgSILENT for two extreme (light and heavy loading) operating conditions.
Pipelzadeh Y, Chaudhuri B, Green TC, 2010, Stability Improvement through HVDC Upgrade in the Australian Equivalent System, UPEC 2010
Pipelzadeh Y, Chaudhuri B, Green TC, 2010, Decentralised Control for Damping Multi-Modal Oscillations through CSC/VSC Based HVDC Transmission Technologies, The 9th international conference on AC and DC power transmission (ACDC 2010)
Pipelzadeh Y, Chaudhuri B, Green TC, 2010, Wide-area Power Oscillation Damping Control through HVDC: A case study on the Australian equivalent network, IEEE Power and Energy Society General Meeting 2010, Minnesota, USA
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