Improve Power Quality and Reduce Harmonics
More and more loads in the network work non-linearly, which has strong repercussions on the network and its quality deteriorates. With EPCOS PQSine ™, an active harmonic filter, network perturbations can be reliably reduced.
In industrial plants, office buildings, data centers and private households, there are hardly any electrical consumers that absorb the current linearly. Examples of non-linear loads include frequency converters in drive technology as well as the large number of clocked power supplies in information and communication technology devices, and increasingly in household electronics. The lighting technology also works on the basis of mostly non-linear power supplies. (Illustration 1). Figure 1: Voltage and current profile of non-linear loads The non-linear current consumption leads to harmonic currents, which result in distortion of the sinusoidal voltage, which in turn disturb other consumers. Harmonics are integer multiples of the fundamental frequency, ie the line frequency of 50 Hz or 60 Hz, which have different amplitudes and extend into the upper kHz range. Harmonics have a number of negative effects on energy quality, including:
Problems for other consumers due to poor network quality;
additional current load of the neutral conductor, since in it harmonic currents of the 3rd, 9th, 15th, 21st order, etc. add up and lead to unacceptably high currents;
Phase unbalance (especially when operating 1-phase switching power supplies), which also favors the generation of harmonics.
In addition, sensitive devices can be disturbed or even destroyed by being coupled in via data or power lines. Typical examples of this are process computers in production plants or data centers, which can cause enormous damage due to wrong data or data loss.
Often it is attempted to eliminate with the help of passive components harmonics directly to the consumer who generates them. For this, however, a corresponding, well-tuned absorption circuit of capacitances and inductors is required for each frequency. This solution is therefore only practicable if a limited spectrum of harmonics occurs.
Active harmonic filters eliminate harmonics With the EPCOS PQSine series TDK now offers a solution that solves many problems caused by harmonics and phase shifts fully automatically and elegantly. To do this, PQSine is connected to the mains parallel to the load causing the harmonics. At the heart of the new Active Harmonic Filter is a controller based on a 32-bit digital signal processor (DSP) operating at a sampling rate of 48 kHz. With a response time of only 21 μs, PQSine is among the best in its class because the newly developed SDC (Selective Drive Control) algorithm is faster than the commonly used Fast Fourier Analysis (FFT) based algorithms. Based on the real-time data, a compensation current is now fed into the grid, Figure 2: Functional principle of EPCOS PQSine The PQSine series is designed for 3-phase networks with and without neutral at voltages from 200 V AC to 480 V AC at 50/60 Hz. With PQSine, harmonics up to the 50th harmonic (2500 Hz / 3000 Hz) can be detected and filtered , The new filters can be cascaded in increments of 60 A up to a maximum compensation current of 600 A in a single filter system. High flexibility due to modular design An enormous advantage is the modular design of PQSine: the 60 A modules can be replaced quickly; In addition, a 180 A filter cabinet can be quickly upgraded with one or two 60 A modules up to a total output of 300 A (5 modules). For this, the modules are simply pushed into the cabinet, whose busbar is basically designed for currents up to 300 A (Figure 3). For contacting, there is no need to screw or drill because both the power connections and the control cables can be plugged in. Figure 3: Different assembly and mounting options In contrast to the classic reactive power compensation, which only compensates for inductive loads, PQSine can also compensate for capacitive reactive power components. In addition to the excellent filtering, the Active Harmonic Filters of the PQSine series also ensure symmetry of the loads across all phases. When using the 4-wire devices, additional neutral conductor currents are compensated. Optimized reliability is ensured by a range of self-monitoring systems. The most important ones are: overload protection, over-temperature shutdown, over-voltage or under-voltage protection and fan monitoring. For easy entry and reading of data, a 7-inch and 12.1-inch TFT color touch screen is available. EtherCAT with 100 Mbit / s, USB, Active Sensor Bus and Display Bus are used as interfaces.
