A comparative case study of online voltage instability monitoring

Loadability analysis based on short‐circuit power

“…The voltage exponent n allows to generate a maximum VPSI S in function of load apparent power S S , load angle θ and factor k. In other words, it is possible to generate a maximum VPSI S in a predefined loadability value by calculating n from (19) and (21) considering S S equal to S S0 from (14).…”

“…In the present case, the maximum VPSI occurs at S equal to 3.0, in consequence the S SC , applying (26), correspond to 10 p.u., as it is expected. Once S SC is known, it is possible to find V S using (19), after that E is obtained and finally Z TH can be determined. In this paper, this interesting condition is used to define a basic scheme of voltage stability monitoring based on S SC as it will be presented in the next section.…”

“…On the other hand, other analyses have demonstrated that Thevenin impedance criterion must be treated carefully for multiload systems [18]. Basic generators steady-state models, such as ideal voltage sources, can produce incorrect interpretations of TE due to the non-linearity of power systems [19].…”

Signal processing for TFR of synchro‐phasor data

“…Extensive research in applying PMU information to improve situational awareness has been conducted including islanding detection [4], state estimation [5,6], dynamic security assessment [7,8] and visualisation [9]. Similarly, Duong et al [10] compare computation of Thevenin impedance using either phasor measurements or its combination with system network. The reported approach is applied for online monitoring of voltage stability during normal operation and disturbance conditions.…”