Analysis Of Power Quality Problems Research Articles

On-line analysis of power quality problems in non-sinusoidal/non-linear distribution systems

On-line analysis of power quality problems in non-sinusoidal/non-linear distribution systems

Analysis of Power Quality Problems on Nigerian 330 kV Power System Using Statcom with Voltage Sensitivity Index

Transmission system is the transportation of electrical energy from generating stations to load centers. However, increase usage of non-linear loads from the consumers has led to electrical Power Quality (PQ) problems which have negative impacts on the operation of the power system especially Nigerian power system. This research analyzed the PQ problem on Nigerian 330 kV power system. Newton-Raphson (NR) iterative method was used to performed load flow analysis on Nigerian 28-bus transmission systems. Then power injection model of the Static Synchronous Compensator (STATCOM) was incorporated to modify the NR mathematical model. The suitable placement for the STATCOM in the system was determined using Voltage Sensitivity Index (VSI) and simulation was done in MATLAB/SIMULINK. The results showed that, the suitable placements of STATCOM controller in the power system were buses 5, 8, 12 and 16. The corresponding STATCOM reactive power, sag voltage and sag duration for buses 5, 8, 12 and 16 were 72.56 MVar, 0.77454 p.u, 0.7336s; 65.35 Mvar, 0.7464 p.u, 0.7419 s; 50.86 Mvar, 0.7615 p.u, 0.6512 s and 53.75 MVar, 0.7442 p.u. 0.5972 s, respectively. Therefore, the results have established the importance of STATCOM with VSI in obtaining suitable solution for PQ problems on electrical power system. Keywords: Transmission System, Electrical Energy, Non-linear Load, Power Quality, Newton-Raphson, STATCOM, Voltage Stability Index. DOI: 10.7176/ISDE/12-6-03 Publication date: October 31 st 2022

Analysis of power quality problems in DC distribution network

With the application and popularization of distributed power supply and power electronic equipment in power grid, AC distribution is faced with problems such as low efficiency and low power quality. At the same time, due to the advantages of large power supply capacity, long power supply radius, high efficiency, good controllability and adaptability to renewable energy access, DC power distribution has become a crucial development direction of the future distribution system. Reasonable and systematic analysis of power quality problems of DC distribution network plays an important role in its construction and application. Firstly, this paper introduces the background, significance and status of the research on DC distribution network and its power quality. Then introduces the three main topology of DC distribution network structure and connection mode. After selecting pseudo bipolar structure to build the simulation circuit, the power quality phenomena such as voltage sag are simulated and analyzed by PSCAD. The results obtained are consistent with theoretical analysis.

Analysis of Power Quality Problems in Large-Scale Application of Air-Source Heat Pump

With the implementation of electric energy alternatives, the large-scale application of electric energy substitution represented by air-source heat pumps has replaced traditional coal-fired heating, which is beneficial for the environment and alleviates air pollution. However, the large-scale application of air-source heat pumps has brought power quality problems such as voltage sags, harmonic pollution, and three-phase imbalance to the distribution network. This paper studies the fixed-frequency and variable-frequency air-source heat pump, introduces its working principle, analyzes the mechanism of its power quality problem. Moreover, the paper establishes a simulation model for the fixed-frequency heat pump and variable-frequency heat pump to connect to the distribution network. This research mainly studies the impact of large-scale fixed-frequency heat pumps on the depth of voltage sags in the distribution network and the impact of large-scale variable-frequency heat pumps on the harmonic content of the distribution network under different penetration rates and uses measured data to verify the reliability of the simulation results. This paper uses experimental data for the first time to verify the real power quality problems of large-scale heat pumps, which can provide a reference for determining the power quality standards for heat pumps connected to the power grid. At the same time, it can also provide a reference for the power quality management of the distribution network that is actually connected to electric heating.

Power Quality: Scientific Collaboration Networks and Research Trends

Power quality is a research field related to the proper operation of devices and technological equipment in industry, service, and domestic activities. The level of power quality is determined by variations in voltage, frequency, and waveforms with respect to reference values. These variations correspond to different types of disturbances, including power fluctuations, interruptions, and transients. Several studies have been focused on analysing power quality issues. However, there is a lack of studies on the analysis of both the trending topics and the scientific collaboration network underlying the field of power quality. To address these aspects, an advanced model is used to retrieve data from publications related to power quality and analyse this information using a graph visualisation software and statistical tools. The results suggest that research interests are mainly focused on the analysis of power quality problems and mitigation techniques. Furthermore, they are observed important collaboration networks between researchers within and across countries.

Modeling and analysis of power quality problems caused by coreless induction melting furnace connected to distribution network

The development of power electronic devices offers the production of high-power current-source inverter-based coreless induction melting furnaces (CSI-CIMFs) for steel scrap melting process. These high-power CSI-CIMFs introduce many advantages in melting processes for low production rate steel mill and foundries. Besides the advantages of CSI-CIMF, it has unfamiliar time-varying harmonic and interharmonic characteristic. In this paper, operating principle and cause of time-varying harmonic and interharmonic characteristic of CSI-CIMF is clearly presented. The time-varying harmonic and interharmonic characteristic of CSI-CIMF is studied by simulation and field measurements of a real 10 MVA CSI-CIMF. The effect of time-varying harmonics and interharmonics of CSI-CIMF on power system is presented by harmonic analysis. The simulation model of CSI-CIMF is developed in PSCAD/EMTDC by using nameplate parameters and field measurements of a real 10 MVA CSI-CIMF in a steel mill which is located in Iskenderun, Turkey.

Harmonic Domain Dynamic Transfer Function of a Nonliner Time-Periodic Network

This paper presents a new concept called harmonic domain dynamic transfer function (HDDTF), which characterizes the dynamics of a nonlinear, time-periodic network as seen from a port (or multiple ports), in terms of the frequency response of harmonic perturbations superimposed on its underlying periodic steady state. It pertains to the transient behavior superimposed on the steady state. The HDDTF is a transfer-function matrix H(s) relating the vectors of harmonic domain input and output endowed with s-domain properties. Because the network can contain saturable (nonlinear) elements and periodically-switching (time-periodic) power electronics components, the HDDTF may be used for the analysis of power quality problems. It may also serve for the identification of a reduced-order dynamic equivalent of a nonlinear, time-periodic network to be used in time-domain transient simulations. The HDDTF is obtained by linearization, about the periodic steady state, of the nonlinear state equations describing a given network. Following the derivation of the HDDTF, a modal analysis to characterize the HDDTF by its diagonalization is presented. Two test systems are used to produce numerical examples.

Improved three-phase load flow using phase and sequence components

The single-phase load flow is efficiently optimised for the rapid solution of power flow and voltages in large systems. The three-phase load flow, at present treated simply as an extension of the single-phase load flow, is primarily used to calculate asymmetry at fundamental frequency throughout the transmission system. A new three-phase load flow, radically different from the single-phase load flow, is proposed. The new load flow is more suited to the analysis of power quality problems in the transmission system. A mixed combination of sequence and phase component mismatches is used, with emphasis on robust convergence rather than speed. It is shown that the three-phase load flow will find one of two solutions at each load busbar, one of which corresponds to abnormal levels of zero sequence voltage. The abnormal solution can be avoided by ensuring a path for zero-sequence current from the load.