Security-Constraint Unit Commitment for AC/DC Transmission Systems with Voltage Stability Constraint
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ORIGINAL ARTICLE
Security‑Constraint Unit Commitment for AC/DC Transmission Systems with Voltage Stability Constraint Ningyu Zhang1 · Shengjun Wu1 · Haiyun An1 · Xinyao Zhu1 Received: 21 October 2019 / Revised: 22 May 2020 / Accepted: 11 August 2020 © The Korean Institute of Electrical Engineers 2020
Abstract Due to the inherent characteristics of weaker voltage supporting ability, line-commutated converter based HVDC technologies have significant effects on AC/DC hybrid power grid’s voltage stability. These has led to new challenges for power grid operators in terms of ensuring power system security. To address these challenges, a unit commitment of receiving-end in AC/DC hybrid grid is presented in this paper. In the proposed model, we employ static voltage stability constraints to guarantee enough voltage supporting capacity from thermal plants at HVDC feed-in area. Based on the characteristics of the model, Benders decomposition and mixed integer programming algorithm are used to get the optimal transmission power of HVDC and schedule of thermal generators. The study is done by considering IEEE-39 and Jiangsu power grid in eastern China, containing two and three HVDC transmission projections respectively. Numerical results on two benchmark problems illustrate the effectiveness of the proposed algorithm, both in terms of convergence rate and solution quality. Keywords Hybrid AC/DC power grid · Unit commitment · High voltage direct current (HVDC) blocking · Voltage stability · Benders decomposition · Mixed integer programming (MIP) List of Symbols VdR, VdI DC voltage of rectifier / inverter Id DC current kR, kI Transformer tap ratio of rectifier/inverter α Trigger delay angle γ Extinguishing angle Vmt , Vnt Voltage of AC bus m /n (at time t) Xc,R, Xc,I Leakage reactance of rectifier/inverter nR , nI Bridge number of rectifier/ inverter Rd Resistance of HVDC line PdR, PdI Real power of rectifier/ inverter QdR, QdI Exchange reactive power between rectifier/ inverter substation and AC grid * Ningyu Zhang [email protected] 1
QCR, QCI Reactive power compensation of rectifier/inverter substation i Index of units l Index of HVDC t Index of hours m, n Index of AC bus T Number of scheduling periods NB Number of buses NL Number of HVDC Csum The total operation cost Ci Cost function ( ) of unit i,
Ci = ai PtG,i
2
+ bi PtG,i + ci
uti On/off state of generating unit i at time t ai, bi, ci Coefficients of cost function PtL,m , QtL,m Real and reactive load of bus m at time t PtG,i , QtG,i Real/reactive generation of unit i rit Reserve capacity of unit i at time t
State Grid Jiangsu Electric Power Company Limited Research Institute, Nanjing, China
13
Vol.:(0123456789)
Journal of Electrical Engineering & Technology
Ptd,l , Qtd,l Real and reactive power of DC l at time t P̄ i,max , Pi,min Upper and lower output limit considering ramp capacity of unit i P̄ G,i,max , PG,i,min Upper and lower real power limit of unit i ̄ G,i,max Q Q Upper/lower reactive power G,i,min
limit of unit i
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