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Using Advanced Derivative Information from Digital Devices

IP.com Disclosure Number: IPCOM000212850D
Original Publication Date: 2011-Nov-30
Included in the Prior Art Database: 2011-Nov-30
Document File: 2 page(s) / 129K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

The digital devices present used in distribution networks are currently used to make only point to point measurements. The devices do not store any historical information and thus the measurements made by the devices are lost and cannot be used for future analysis. Many distribution network applications require accurate measurements from the field level in order to be able to do proper analysis of the network. The measurements made by the digital devices can be saved in a database as a look-up table, in order to be used by the applications in their algorithms.

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Using Advanced Derivative Information from Digital Devices

Idea: Dr. Izudin Dzafic, DE-Nuremberg

The digital devices present used in distribution networks are currently used to make only point to point measurements. The devices do not store any historical information and thus the measurements made by the devices are lost and cannot be used for future analysis. Many distribution network applications require accurate measurements from the field level in order to be able to do proper analysis of the network. The measurements made by the digital devices can be saved in a database as a look-up table, in order to be used by the applications in their algorithms.

Applications for example like Volt/VAR control (VVC) are operable on the principle of δQ / δV, where δQ is a measure of the change of VARs and δV is a measure of the change of voltage, where change active power ΔP ≈ 0 or/and ΔQ >> ΔP. The Q and V values used to derive δQ / δV, in VVC or in other applications are mostly simulated based on the network models. There are two basic problems with this approach. The first is the lack of accuracy, and less reliability in the analysis done by the applications, and the second is a loss of performance.

The novel idea is that a digital device present in the field, which already measures the voltage and current at the terminals, performs the calculation of this derivation δQ / δV between periods of time where ΔP ≈ 0. The device can thus store these calculated values in a look-up table, along with the IDs of the transformers, lines, loads etc. as hash-sets. When the user or an application needs these values in its algorithm, it is possible just to search for its network configuration in the look-up table and obtain the value.

In detail, the digital devices distributed over the distribution network measure P, Q, V etc. at any given time t. In order to calculate the derivative δQ / δV, the device has to save the values at any point of time say t = t0, and measure again at time t = t1. If, ΔP ≈ 0, then ΔQ / δV = (Q1 - Q0) / (V1 - V0).

The derivatives thus calculated are stored in a look-up table. The look-up tables are created in the following manner (see Figure 1):

Step 1...