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Operation Simulation and Analysis
Published in Chengshan Wang, Jianzhong Wu, Janaka Ekanayake, Nick Jenkins, Smart Electricity Distribution Networks, 2017
Chengshan Wang, Jianzhong Wu, Janaka Ekanayake, Nick Jenkins
Among many electric power quality issues, the damage caused by voltage fluctuation, such as temporary voltage reduction, increase or flicker, is the most common. The function of a dynamic voltage regulator (DVR) is mainly to compensate voltage sags. It is a powerful means to reduce the influence of voltage fluctuation. Especially with an increasing connection of distribution generations such as wind power, it should take measures to stabilize the voltage at the point of grid connection of DGs and enhance the low voltage ride-through capability of DGs. Under normal conditions, the DVR does not compensate the voltage at the point of grid connection. When faults occur, the DG terminal voltage can be compensated by DVR, enabling the DGs and loads to remain in the grid-connected operation [9]. The single-phase structure of a DVR is shown in Figure 6.9.
An improved sag detection approach based on modified Goertzel algorithm
Published in International Journal of Electronics, 2019
Ehsan Najafi, A.H.M. Yatim, Amin Mirzaei
Sag can be defined as a decrease between 0.1 and 0.9 pu in RMS voltage or current at the power frequency for durations of several milliseconds to 1 min (IEEE Recommended Practice for Monitoring Electric Power Quality, 1995). The value of voltage sag is defined by the magnitude of actual voltage during the disturbance. There are many causes for voltage sag such as grid faults, inrush currents and starting of large motors. These problems arise from utility of customer side. Lightning may also lead to a voltage sag (Naidoo & Pillay, 2007; Polajz, Rtumberger, & Dolinar, 2015). Although there are many methods nowadays to mitigate this power quality problem such as dynamic voltage restorer (DVR) (Kassarwani, Ohri, & Singh, 2017) and STATCOM (Deben Singh, Mehta, Singh, & Meng, 2016), the key part in these equipments is sag detection algorithm. Some algorithms face some constraints and are sophisticated for implementation, while others may lack precision or speed of detection (Jian, Cao, Jintao, & Yinge, 2017).
A Novel Hybrid Optimization Controlled DSTATCOM Model for Power Quality Enhancement
Published in Cybernetics and Systems, 2023
In distribution networks, DSTATCOM is a shunt-connected Voltage Source Converter (VSC) that has been used to correct the bus voltage in order to improve power factor and reactive power control. Capacitive and inductive mode correction can be quickly and continuously provided by DSTATCOM. When connected to a particular load, DSTATCOM can inject enough leading or trailing compensatory current to ensure that the overall demand matches the requirements for utility connection. The consequence of power quality while connecting the distribution grid to non-linear loads is distressing and it may be the most important issue to look into. A solid-state CB that is attached will open to disconnect the load from the grid if a severe voltage imbalance occurs. When there is just a mild voltage imbalance, the CB remains closed, causing the PCC to experience continuous voltage imbalance. Although there have always been issues with power quality in the power system, rectification techniques have improved recently. Electric power quality is the preservation of a power distribution bus voltage that is close to sinusoidal at the specified frequency and magnitude. The energy delivered to a client must also be evaluated for consistency perspective. The main power quality issues that impact the utility system include voltage imbalance, harmonic content, increased reactive power demand, and frequency deviation. In general, losses in AC power lines are increased by current harmonics and voltage-frequency imbalance (Natesan et al. 2014). For voltage-frequency regulation, a typical PI regulator and synchronous reference frames-based current control loop is utilized (Al-Saedi et al. 2012). In (Kim, Yu, and Choi 2008), an indirect current control approach was used to reduce voltage imbalance. According to research by (Kahrobaeian and Mohamed 2012), DGs are capable of providing great flexibility, resilience, and varied control of active and reactive power (p, q) in both grid-tied and islanded modes. Numerous modification approaches have been used (Timbus et al. 2009) to enhance the performance of the DG controller. Voltage, frequency, and harmonic distortion are the primary power quality characteristics; harmonic distortion has been addressed by the use of SVC and SAPF (Xiaozhi, Linchuan, and Wenyan 2011). To control frequency and voltage in microgrids that are grid-tied or islanded, the frequency and voltage control mode is used (Blaabjerg et al. 2006). In both grid and autonomous operation, the droop control approach offers an effective methodology to improve power quality parameters including active and reactive power regulation. Voltage and current have been controlled using the droop control approach to offer PQ control in microgrids, which have been studied (Chung et al. 2010).