TY - JOUR
T1 - Static voltage stability analysis of distribution systems based on network-load admittance ratio
AU - Song, Yue
AU - Hill, David J.
AU - Liu, Tao
N1 - Funding Information:
Manuscript received June 7, 2018; revised October 10, 2018; accepted December 1, 2018. Date of publication December 13, 2018; date of current version April 17, 2019. This work was supported in part by the Hong Kong Ph.D. Fellowship Scheme, and in part by the Research Grants Council of the Hong Kong Special Administrative Region through the General Research Fund under Project 17208817 and through the Theme-Based Research Scheme under Project T23-701/14-N. Paper no. TPWRS-00879-2018. (Corresponding author: Yue Song.) Y. Song and T. Liu are with the Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong (e-mail:, [email protected]; [email protected]).
Publisher Copyright:
© 1969-2012 IEEE.
PY - 2019/5
Y1 - 2019/5
N2 - It is well known that a single (constant power) load infinite-bus system reaches a static voltage stability limit point, or equivalently, a singularity point of the power flow Jacobian, at the unity line-load admittance ratio, i.e., the equivalent admittance of the load has the same modulus as the transmission line admittance. In this paper, we rigorously extend this result to generic distribution systems with distributed generators (DGs). We introduce a new concept called the network-load admittance ratio that is in terms of the parameters of power network, loads, and DGs. This concept is a generalization of the line-load admittance ratio that characterizes the loading status of a distribution system with the effects of DGs included. We prove that the power flow Jacobian is singular if and only if the network-load admittance ratio is unity, which provides new insights into the mechanism of voltage stability. In addition, we establish a new voltage stability index by using the network-load admittance ratio. Numerical simulations on several IEEE test systems show that the index has good linearity with load increase and estimates voltage stability margin with high precision. The index also reflects the impact of DG penetration level and control mode on voltage stability. The obtained results can be extended to ZIP load models, unbalanced three-phase networks, and mesh networks with slight modifications.
AB - It is well known that a single (constant power) load infinite-bus system reaches a static voltage stability limit point, or equivalently, a singularity point of the power flow Jacobian, at the unity line-load admittance ratio, i.e., the equivalent admittance of the load has the same modulus as the transmission line admittance. In this paper, we rigorously extend this result to generic distribution systems with distributed generators (DGs). We introduce a new concept called the network-load admittance ratio that is in terms of the parameters of power network, loads, and DGs. This concept is a generalization of the line-load admittance ratio that characterizes the loading status of a distribution system with the effects of DGs included. We prove that the power flow Jacobian is singular if and only if the network-load admittance ratio is unity, which provides new insights into the mechanism of voltage stability. In addition, we establish a new voltage stability index by using the network-load admittance ratio. Numerical simulations on several IEEE test systems show that the index has good linearity with load increase and estimates voltage stability margin with high precision. The index also reflects the impact of DG penetration level and control mode on voltage stability. The obtained results can be extended to ZIP load models, unbalanced three-phase networks, and mesh networks with slight modifications.
KW - Distribution network
KW - power flow Jacobian
KW - singularity point
KW - voltage stability
KW - voltage stability index
UR - http://www.scopus.com/inward/record.url?scp=85058626267&partnerID=8YFLogxK
U2 - 10.1109/TPWRS.2018.2886636
DO - 10.1109/TPWRS.2018.2886636
M3 - Article
AN - SCOPUS:85058626267
SN - 0885-8950
VL - 34
SP - 2270
EP - 2280
JO - IEEE Transactions on Power Systems
JF - IEEE Transactions on Power Systems
IS - 3
ER -