Unified Power Flow Algorithm Based on the NR Method for Hybrid AC/DC Grids Incorporating VSCs

Chai, Runze; Zhang, Baohui; Dou, Jingming; Hao, Zhiguo; Zheng, Tao

doi:10.1109/tpwrs.2015.2511303

Cited by 75 publications

(48 citation statements)

References 19 publications

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“…V dc,1 − V dc,2 = R dc,12 I cc,12 (real) ⇔ V dc,1 − V dc,2 = R dc,12 I cc,12 (p.u) (41) P cc,12 = 2V dc,1 I cc,12 (real) ⇔ P cc,12 = V dc,1 I cc,12 (p.u) (42) where V dc,i is the voltage at DC bus i (pole to ground), P cc,ij is the total power leaving DC line ij (through both poles), I cc,ij is the current through DC line ij (through each pole) and R dc,ij is the resistance of DC line ij (of each pole…”

Section: Appendix: Ac/dc Per Unit System Usedmentioning

confidence: 99%

A simplified algorithm to solve optimal power flows in hybrid VSC-based AC/DC systems

Renedo

Ibrahim

Kazemtabrizi

et al. 2019

International Journal of Electrical Power & Energy Systems

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2019) 'A simplied algorithm to solve optimal power ows in hybrid VSC-based AC/DC systems.', International journal of electrical power and energy systems, 110 . pp. 781-794.The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractHigh Voltage Direct Current systems based on Voltage Source Converters (VSC-HVDC) are increasingly being considered as a viable technology with advantages, above all when using underground or submarine cables for bulk power transmission. In order to fully understand how VSC-HVDC systems can be best used within existing power systems, it is necessary to adapt conventional tools to carry out system-wide studies including this technology. Along this line, this paper proposes a simplified algorithm to solve optimal power flows (OPFs) in hybrid VSCbased Alternating Current / Direct Current (AC/DC) grids with multi-terminal VSC-HVDC systems. The proposed algorithm makes it possible to seamlessly extend a previous large-scale AC case to which several multi-terminal VSC-HVDC systems must be added. The proposed approach combines two ideas used previously in two different modelling approaches: each VSC is modelled as two generators with a coupling constraint; and DC grids are modelled as notional AC grids, since, in per unit, the equations for the former are a particular case of the latter with resistive lines and no reactive-power injections. In the proposed approach, the hybrid VSC-based AC/DC system is transformed into an equivalent only-AC system. Therefore, the OPF solution of the AC/DC system can be found with the same tool used for the previous AC problem and a simple extension of the original case.Index Terms VSC HVDC, HVDC transmission, multi-terminal, optimal power flow, power systems. NOMENCLATUREA G , A bus , A branch , A slacks : Sets of the generators, buses, branches and slack buses of the AC grids, respectively. A vsc , A dcbus , A dcbranch : Sets of the VSC stations, buses and branches of the multi-terminal VSC-HVDC systems. V i = V i ∠θ i : Voltage at AC bus ī S G,i = P G,i + jQ G,i : Active-(P) and reactive-power (Q) generation (bus i) S D,i = P D,i + jQ D,i : P/Q consumed by the loads (bus i) S i = P i + jQ i : P/Q injections into the AC grid at bus ī Y bus,ik = G ik + jB ik : Admittance matrix of AC line (i, k) I ik : Current through AC branch (i, k) (leaving bus i) (magnitude) S ik = P ac,ik + jQ ac,ik : P and Q flows through AC branch (i, k) (leaving AC bus i) Z ac,ik = R ac,ik + jX ac,ik : Series impedance of AC branch (i, k) B ac,sh,ik : Shunt susceptance of AC branch (i, k) V s,i = V s,i ∠δ s,i ...

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Section: Appendix: Ac/dc Per Unit System Usedmentioning

confidence: 99%

A simplified algorithm to solve optimal power flows in hybrid VSC-based AC/DC systems

Renedo

Ibrahim

Kazemtabrizi

et al. 2019

International Journal of Electrical Power & Energy Systems

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show abstract

“…where z j 1 , z j 2 , and z j 3 are independent standard normal variables; a j 1 , a j 1 ,j 2 , and a j 1 ,j 2 ,j 3 are the parameters that should be estimated; and H k represents a multidimensional Hermite polynomial of the order k (k = 1, 2, 3, . .…”

Section: Functional Representation Of the Power Flow Modelmentioning

confidence: 99%

“…The parameters of the IEEE 118-bus system can be found in Matpower 6.0 as in reference [25]. The parameters of the VSCs and DC lines are given in reference [3]. In this paper, the control modes of the VSCs are presented in Table 2.…”

Section: System Data and Study Scenariosmentioning

confidence: 99%

“…Increasingly, many countries are choosing to build large-scale wind farms (WFs) in places with superior wind conditions [2]. Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) is considered to be an effective solution for large-scale WFs because it has the ability to independently control the active and reactive power and to support voltage of the AC bus [3]. Compared with VSC-HVDC, the VSC-Multiple Terminal Direct Current (VSC-MTDC) could facilitate the integration of fluctuant wind power and improve the transfer efficiency and operational security [4].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Improved Stochastic Response Surface Method Based Probabilistic Load Flow for Studies on Correlated Wind Speeds in the AC/DC Grid

2018

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This paper proposed a probabilistic load flow technique of AC/VSC-MTDC (Alternate Current/Voltage Source Control-Multiple Terminal Direct Current) hybrid grids based on an improved stochastic response surface method. The applied traditional stochastic response surface method is inherent with the capability to tackle correlated normal variables; however, the accuracy is poor in the case of correlated diverse distributions. To address this issue, NATAF transformation was adopted to transform the correlated wind speeds and loads following arbitrary distributions into the variables that are subject to standard normal distributions. The collection points could be selected to establish the polynomial relationship among the independent standard normal variables and the output responses. Then, the probability distributions and statistics of the responses could be accurately and efficiently estimated. The modified IEEE 14-bus system, involving an additional VSC-MTDC system, wind speeds following various distributions, and diverse consumer behaviors, was used to demonstrate the validity and capability of the proposed method.

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“…This process is achieved by AC/DC power flow calculations. As for AC/DC power flow solutions, both unified algorithms [21][22][23] and sequential algorithms [24][25][26][27] are theoretically feasible. Specific to AC/DC networks embedded with hybrid HVDC systems, only a few papers addressed their power flow solutions.…”

Section: Introductionmentioning

confidence: 99%

Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems

Liang

Xiao

et al. 2018

Energies

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Abstract:A method for electromechanical modeling of line commutated converter (LCC)-modular multilevel converter (MMC)-based hybrid multi-terminal High Voltage Direct Current Transmission (HVDC) systems for large-scale power system transient stability study is proposed. Firstly, the general idea of modeling the LCC-MMC hybrid multi-terminal HVDC system is presented, then the AC-side and DC-side models of the LCC/MMC are established. Different from the conventional first-order DC-side model of the MMC, an improved second-order DC-side model of the MMC is established. Besides considering the firing angle limit of the LCC, a sequential power flow algorithm is proposed for the initialization of LCC-MMC hybrid multi-terminal HVDC system. Lastly, simulations of small scale and large scale power systems embedded with a three-terminal LCC-MMC hybrid HVDC system are performed on the electromechanical simulation platform PSS/E. It is demonstrated that if the firing angle limit is not considered, the accuracy of the power flow solutions will be greatly affected. Steady state calculation and dynamic simulation show that the developed LCC-MMC hybrid MTDC model is accurate enough for electromechanical transient stability studies of large-scale AC/DC system.

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Unified Power Flow Algorithm Based on the NR Method for Hybrid AC/DC Grids Incorporating VSCs

Cited by 75 publications

References 19 publications

A simplified algorithm to solve optimal power flows in hybrid VSC-based AC/DC systems

A simplified algorithm to solve optimal power flows in hybrid VSC-based AC/DC systems

An Improved Stochastic Response Surface Method Based Probabilistic Load Flow for Studies on Correlated Wind Speeds in the AC/DC Grid

Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems

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