Method for voltage instability load shedding using local measurements
First Claim
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1. A method of voltage instability load shedding, comprising the steps of:
- (a) measuring current and voltage waveforms of an electrical system at a local system bus;
(b) estimating a Thevenin equivalent admittance (Y) based on Kalman filter techniques using z=Hx+ v where z is a measurement vector, x is a state vector to be estimated, H is an observation model, v is an observation noise, wherein an initial value x is set based on a power flow solution, a covariance matrix of measurement error R set according to an accuracy of a measurement device, and an initial value of a covariance of an estimation error P set as a diagonal matrix with an element value equal to 0.000001;
(c) calculating a voltage stability margin index using a magnitude of the voltage waveform, a determined Thevenin admittance, and a load at the local system bus;
(d) comparing the calculated voltage stability margin index with a predetermined threshold value; and
(e) utilizing the comparison between the calculated voltage stability margin index with the predetermined threshold value to determine whether to initiate a load shedding action.
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Abstract
A method of voltage instability load shedding, that includes the steps of measuring current and voltage waveforms of an electrical system at a local bus estimating the Thevenin equivalent admittance based on Kalman Filter techniques, then a voltage stability margin index is calculated using the voltage magnitude. The determined Thevenin admittance and the load at the local system bus and the calculated voltage stability margin index is compared with a predetermined threshold value to determine whether to initiate a load shedding action.
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Citations
5 Claims
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1. A method of voltage instability load shedding, comprising the steps of:
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(a) measuring current and voltage waveforms of an electrical system at a local system bus; (b) estimating a Thevenin equivalent admittance (Y) based on Kalman filter techniques using z=Hx+ v where z is a measurement vector, x is a state vector to be estimated, H is an observation model, v is an observation noise, wherein an initial value x is set based on a power flow solution, a covariance matrix of measurement error R set according to an accuracy of a measurement device, and an initial value of a covariance of an estimation error P set as a diagonal matrix with an element value equal to 0.000001; (c) calculating a voltage stability margin index using a magnitude of the voltage waveform, a determined Thevenin admittance, and a load at the local system bus; (d) comparing the calculated voltage stability margin index with a predetermined threshold value; and (e) utilizing the comparison between the calculated voltage stability margin index with the predetermined threshold value to determine whether to initiate a load shedding action. - View Dependent Claims (2, 3, 4, 5)
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