Understanding Power Quality: A Guide to Improving Your Electrical System
Power quality is an important aspect of any electrical system, especially in distribution networks where loads are often sensitive to voltage fluctuations, harmonics, and other disturbances. One way to improve power quality is to use a device called DSTATCOM (Distribution Static Compensator), which can inject or absorb reactive power to regulate the voltage and compensate for the load variations. However, DSTATCOM alone may not be enough to deal with severe power quality issues, such as voltage sags or swells, caused by faults or switching events. In such cases, a battery energy storage system (BESS) can be added to the DSTATCOM to provide active power support and enhance the performance of the device.
In this blog post, I will explain how a DSTATCOM with BESS can improve power quality in distribution networks, and present some simulation results to demonstrate its effectiveness. I will also discuss some challenges and opportunities for implementing this technology in real-world scenarios.
DSTATCOM with BESS: How does it work?
A DSTATCOM is a shunt-connected device that consists of a voltage source converter (VSC), a DC capacitor, and a controller. The VSC can generate or absorb reactive power by varying the amplitude and phase angle of its output voltage, which is connected to the distribution network through a coupling transformer. The DC capacitor provides the energy storage for the VSC operation. The controller determines the reference voltage for the VSC based on the network conditions and the desired power quality objectives.
A BESS is an energy storage device that can store or release electrical energy in the form of DC power. It can be connected to the DC side of the DSTATCOM through a bidirectional converter, which can charge or discharge the battery depending on the direction of power flow. The BESS can provide active power support to the distribution network by supplying or absorbing real power from or to the DC link of the DSTATCOM.
The combination of DSTATCOM and BESS can improve power quality in distribution networks in several ways:
- Voltage regulation: The DSTATCOM can inject or absorb reactive power to maintain the voltage at a desired level, regardless of the load variations or network disturbances. The BESS can provide active power support to enhance the voltage regulation capability of the DSTATCOM, especially during severe voltage sags or swells.
- Harmonic compensation: The DSTATCOM can filter out harmonics from the network by generating harmonic currents that are opposite in phase to those of the load. The BESS can help reduce the harmonic distortion in the network by supplying or absorbing active power that is proportional to the harmonic currents.
- Power factor correction: The DSTATCOM can correct the power factor of the load by generating or absorbing reactive power that is equal and opposite to that of the load. The BESS can improve the power factor correction performance of the DSTATCOM by providing active power support that is in phase with the fundamental component of the load current.
- Load balancing: The DSTATCOM can balance the load currents in a three-phase network by generating or absorbing negative-sequence and zero-sequence currents that are equal and opposite to those of the load. The BESS can assist in load balancing by providing active power support that is proportional to the negative-sequence and zero-sequence currents.
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