Harmonic Analysis

Breif About Harmonic Analysis

Understanding of the general client system

  • Client shall have 33 KV or 11 KV HT Incomer through DP Structure / RMG
  • HT Consumer end incomer panel - with appropriate current rating VCB will be available
  • Client load will be connected through outgoing VCB through Transformer to MV Panel
  • DG sets will be connected in MV Panel along with EB Incomer
  • Load shall include various PCC's and MCC's
  • MCC outgoing may include VFD and soft starter

General Requirement

  • Analyze level of harmonics at various feeder level during peak load
  • Analysis includes determination of THD (Total Harmonic Distortion)
    • Determination of available order of harmonics
    • For example, if the THD value is 15%, we will be determining the order which causes higher harmonics, in this instance - 3rd harmonics may induce 6%, 5th Harmonics may induce 3% and 7th Harmonics may induce 4% and other orders may have negligible values.
  • A report will be created based on the above analysis for each feeder identified for analyzing the harmonic values.

Scope of work for ANALYSIS

  • Will bring a kit with a meter which measures Total Harmonic Distortion at any given point - Both Voltage and Current [THD]
  • Simultaneously the kit will measure the breakup of THD in
    • 3rd harmonics
    • 5th harmonics
    • 7th harmonics
    • 9th harmonics
    • 11th harmonics
  • In most of the cases, the harmonics level shall be falling within the above range. In case, the level of harmonics are higher, we will be adding additional meters in the kit to determine which other level of harmonics is predominant.
  • Shall also measure the various instantaneous parameters at that point of time including the below which we could use for analyzing purposes and determine the quality of power.
  • A complete report will be generated based on the above parameters with time stamp.
  • We propose to take samples of the above instantaneous values for at least 3 hours @ 5 second interval at each feeder during the peak load periods.
  • Once we understand the pattern of harmonics in the specified feeder, we will analyze the output to determine if filters are required to reduce the level of harmonics.
  • As per CEA Standards, the permissible limits for voltage harmonics shall be 5% and current harmonics shall be 8%
    10.1.2 - Harmonics:
    As specified in the Supply Code, when the consumer fails to provide adequate harmonic suppression equipment to avoid dumping of harmonics beyond the limits as specified by CEA regulations into Licensee's distribution system, he is liable to pay compensation at 5% of the respective tariff. As and when the consumer brings down the harmonics within the limit, compensation charges shall be withdrawn. The measurement of harmonics shall be done by the Distribution Licensee using standard meters/equipments in the presence of consumers or their representatives. This compensation provision is applicable to HT-I & HT-III category of consumers. The TANGEDCO shall give three months clear notice to all consumers under these categories stating that they shall pay 15% compensation charges if the harmonics introduced by their load is not within the limits set by CEA. The TANGEDCO shall implement the compensation provision after the three months period if the measured harmonics is more than the limits.
  • Suitable harmonics filter shall be designed with the help of customized design software like MATLAB.

Implementation of Suitable Filters with AUTOMATIC HARMONIC FILTER RELAY

  • Upon designing the appropriate filter which includes reactors, capacitors and / or resistors.
  • Based on the site conditions and space requirements at site, we will be designing small harmonic filter panels with a harmonic filter relay.
  • The Automatic harmonic filter relay is designed uniquely to switch ON / OFF the reactors / capacitors based on the combination of Power factor and Harmonic values present at that instant.

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