Harmonic Analysis can be performed in 3-phase, 2-phase, 1-phase AC systems to test the operating behaviour of the networks at frequencies above 50/60 Hz. The module can be used to compute the network impedance and harmonic level for each frequency and for each node as well as the frequency response of meshed networks. The results can be displayed both in the frequency and time domain and serve as basis for the planning of ripple control systems, dimensioning of compensators (SVC) and harmonic filters, determination of network impedance for sub-synchronous resonance or filter design.

### General Characteristics

- U-I and I-U sensitivity for each frequency
- Distributed parameter line model applied
- Frequency-dependence of elements is considered. Libraries available
- Automatic frequency step length control during impedance computation to detect resonances
- Calculation in the positive component system (symmetrical) or in the phase system
- Calculation of self- and mutual line impedances in function of the frequency
- Harmonic load flow (P, Q, I, U, losses)
- Results in frequency or time domain

### Harmonic Levels

This module computes current and voltage at all frequencies and at all predefined nodes and elements as well as the r.m.s. values for harmonic voltages and currents with fundamental harmonic voltage or current taken from the Load flow (optional). Results are automatically entered in the single line diagram. Harmonic Analysis module also provides comparison of computed harmonic levels with the limit values laid down in any standards desired.

- Computation of total harmonic voltage factor in conformity with DIN/IEC and distortion factor in accordance with IEEE
- Computation of telephone parameters (TIF, IT, KVT) or transformer k-factor
- List output of ripple control currents and voltages at any desired frequencies and at each node and each element
- Harmonic sum calculation: vectorial, geometric, arithmetic, acc. to IEC 1000-2-6

### Harmonic source

Harmonic sources (current and voltage sources) are entered directly in the single line diagram. They can be assigned directly to loads or any power electronic elements, such as Converter, SVC, PWM, etc. Libraries are available. Unlimited number of harmonic sources (current/voltage) can be computed with each harmonic, while any harmonic can be handled, e.g. inter-harmonics due to saturation effects.

### Filter Dimensioning

Filter elements are dimensioned directly by NEPLAN^{ }and are transferred automatically into the single line diagram.

- Filter elements: filters (normal, HP, C-filter), series RLC-circuits with or without earth connection, ripple control traps
- Filter data are listed or saved in a text file
- Result lists can be saved in text files or in result files for evaluation by means of spreadsheet programs (like MS-Excel)