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Tracking oscillation modes in power systems based on wide-area measurements Disclosure Number: IPCOM000249168D
Publication Date: 2017-Feb-08
Document File: 9 page(s) / 473K

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The Prior Art Database

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Adamantios Marinakis: INVENTOR [+3]


One of the most popular applications of wide-area monitoring systems (WAMS) is their ability to estimate the modal characteristics of the various electromechanical oscillation modes that are present in the system, based on ambient synchronized voltage and current phasor measurements which are collected in real-time by phasor measurement units (PMUs) installed at different locations in a power system. Among these characteristics are the frequency and the damping ratio of each of the detected modes. The ABB application who performs this function is called power damping monitoring (PDM) application. PDM works on PMU data collected over a time window (a typical value is 15 min) and periodically (typically, twice per minute) gives the following output per detected oscillation mode: mode frequency, mode damping ratio, modal activity per PMU, i.e. a measure of how visible is the mode in each PMU signal (in the remainder of this document, let us call this "observability" of a mode at a PMU), and total modal activity, i.e. a measure of how visible is the mode by the whole WAMS. Figure 1 shows a typical such outcome. Only two modes are shown per identification run, the blue being the most active and the green being the second most active. PDM is nowadays a standard functionality of a WAMS, offered by ABB and other vendors (under different naming). It allows the system operator to monitor, in real-time, whether the power system operates at a well or poorly damped point. The latter would mean that if an event happens in the system, growing electromechanical oscillations might develop, eventually leading to potential instability. Thus, the system operator would typically modify an operating point which is observed to be poorly damped, restoring its power system to a secure operation state. However, the PDM application does not relate to each other oscillation modes identified at different snapshot executions of the PDM algorithm. In other words, PDM does not track oscillation modes over time; it is not able to detect, for example, that essentially the same mode has been observed at time instant t_1 with modal frequency f_1 and damping ratio d_1 and at time instance t_2 with another modal frequency f_2 and damping ratio d_2

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ABB Type of document  Classification  Information for filing 

Invention Disclosure    ABB Ref.: CH‐1524401    Pl.  from Dept.  Inventors Date Pages


Dä  CHCRC/Automation  Adamantios Marinakis, Mats Larsson,  Alexandru Moga  2017‐02‐06  1/8 


Tracking oscillation modes in power systems based on wide‐area measurements     

We reserve all rights in this document and in the information contained therein. Reproduction, use or disclosure to third parties without express authority is strictly forbidden.   ABB Ltd. 2017 


1. Background 

Brief statement of how things worked before the invention 

One of the most popular applications of wide‐area monitoring systems (WAMS) is their ability to estimate the modal  characteristics of the various electromechanical oscillation modes that are present in the system, based on ambient  synchronized voltage and current phasor measurements which are collected  in real‐time by phasor measurement  units (PMUs) installed at different locations in a power system. Among these characteristics are the frequency and  the damping ratio of each of the detected modes. The ABB application who performs this function is called power  damping monitoring (PDM) application. PDM works on PMU data collected over a time window (a typical value is 15  min) and periodically (typically, twice per minute) gives the following output per detected oscillation mode: mode  frequency, mode damping ratio, modal activity per PMU, i.e. a measure of how visible is the mode in each PMU signal  (in the remainder of this document, let us call this “observability” of a mode at a PMU), and total modal activity, i.e.  a measure of how visible is the mode by the whole WAMS. Figure 1 shows a typical such outcome. Only two modes  are shown per identification run, the blue being the most active and the green being the second most active. 

PDM is nowadays a standard functionality of a WAMS, offered by ABB and other vendors (under different naming).  It allows the system operator to monitor, in real‐time, whether the power system operates at a well or poorly damped  point. The latter would mean that if an event happens in the system, growing electromechanical oscillations might  develop, eventually leading to potential instability. Thus, the system operator would typically modify an operating  point which is observed to be poorly damped, restoring its power system to a secure operation state. 

2. Statement of the problem 

Briefly explain the problem solved with the invention. If applicable explain how the competition solves the problem. 

However,  the PDM  application does not  relate  to  each other oscillation modes  identified  at different  snapshot  executions of the PDM algorithm. In other words, PDM does not track oscillation modes over time; it is not able to  detect, for example, that essentially the same mode has been observed at time instant   with modal frequency    and damping ratio   and at time instance   with another modal frequency ...