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Stability transfer limit calculation in a power transmission network

  • US 5,566,085 A
  • Filed: 11/07/1994
  • Issued: 10/15/1996
  • Est. Priority Date: 09/24/1992
  • Status: Expired due to Fees
First Claim
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1. A method for calculating a transient stability or voltage stability transfer limit in a power network, said network having at least two independent AC generators supplying a common load via separate AC transmission lines having at least one bus, the method comprising the steps of:

  • a) determining steady state values for variable characteristic electrical parameters of variable elements of said network based on particular values for power transferred by said transmission lines;

    b) determining static values for passive characteristic electrical parameters of passive conductive elements of said network;

    c) selecting a contingency resulting in a sudden change of at least one of said variable electrical parameters and said passive electrical parameters;

    d) calculating using said steady state and said static values a post contingency steady state value for a voltage at one of said at least one bus;

    e) calculating using said steady state and said static values a voltage over time during a transition period at said one of said at least one bus, said transition period extending in time from a start of said contingency through a discontinuity during which said voltage at said one bus is abnormally altered, and recovery during which said voltage at said one bus will tend toward a steady state terminal value;

    f) calculating an integral sum of squares of a difference between said post contingency steady state voltage and said transition period voltage over said transition period to obtain an energy value;

    g) changing one of said power values associated with one of said AC transmission lines and repeating said steps a) b) d) e) and f) to obtain two said energy values, said two energy values being non-substantially-infinite;

    h) obtaining a transfer limit estimate for said one transmission line as being an asymptote of said energy values, said energy values being an inverse function of said limit less said one power value.

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