Harmonic mitigation and power quality improvement in utility grid with solar energy penetration using distribution static compensator

Abstract Distribution static compensator is based on power electronic devices technology which is utilized to supply rapid changes in active power as well as reactive power of utility grids. This is useful to achieve corrections in power factor, balancing of load, compensation of current and filtering of harmonics. Therefore, proposed work investigates the improvement of the power quality by utilizing the distribution static compensator, which is equipped by battery energy storage system and interfaced to distribution network with solar photo voltaic (PV) energy integration. In the present study, distribution static compensator is controlled using a control strategy based on the synchronous reference frame theory. Customised IEEE‐13 nodes test system incorporating solar PV generation and distribution static compensator, is utilized to perform the harmonic mitigation and power quality analysis. Disturbances of power quality and harmonics have been investigated due to abrupt changes in the insolation of solar radiation, outage of PV plant from grid and synchronization of PV plant to grid. MATLAB/Simulink environment is utilized to perform the study. Effectiveness of a developed approach is validated by comparing results of simulation with results extracted in real time using real time digital simulator. Results indicate that the developed method is more effective for harmonic mitigation and improving power quality of electrical power in distribution network integrated with solar PV generation. Performance of the approach is compared with the performance of methods reported in the literature to establish the suitability of the method for harmonics mitigation and power quality improvement in grid with solar energy

A Zig-Zag Transformer and Three-leg VSC Based DSTATCOM for a Diesel Generator Based Microgrid

AbstractThe distribution systems are facing severe power quality problems due to the uncontrolled use of different types of linear and non-linear loads such as solid state controllers which will draw harmonics and reactive currents from ac mains. It may lead to poor power quality at ac sources such as sag, swell, notch, flicker, unbalance etc. The installation of the diesel generator set is widely used in practice to feed power to some crucial equipments and in remote areas. DG sets used for these purposes may be loaded with unbalanced, reactive and non-linear loads such as power supplies in telecommunication system and medical equipments. A Zig-Zag Transformer and three-leg VSC based DSTATCOM is used here to compensate the neutral current, harmonic current, reactive power and unbalanced load. The insulated gate bipolar transistor (IGBT) based VSC is supported by a capacitor and is controlled for the compensation required in the load current. The dc bus voltage of the VSC is regulated during varying load conditions. In this paper, a Synchronous Reference Frame (SRF) controlled three-leg voltage source converter (VSC) based DSTATCOM with a Zig-Zag transformer is used for reactive power, harmonics, unbalanced load current and neutral current compensation in grid connected and islanded mode

Interline Unified Power Quality Conditioner for Enhancing Power Quality using FOFPID-based Interleaved CUK Converter

Electrical distribution systems face increased non-linear loads due to using power electronics for the converters. Due to these non-linear loads, the system exhibits PQ problems in the distributed feeders. To enhance PQ problems in the dual feeder, fractional order fuzzy proportional integral derivative controller (FOFPID) is introduced with interline unified power quality (IUPQC) conditioner. IUPQC conditioner includes a distribution static compensator (DSTATCOM), dynamic voltage restorer (DVR) and interleaved cuk converter (ICC). DSTATCOM and DVR are used for compensating the voltages and current in the dual feeders (feeder-1 and feeder-2). Also, ICC monitors the switching between the DSTATCOM and DVR compensators by providing proper power flow. Moreover, the FOFPID controller regulates an input supply from both feeders. The simulation is performed through MATLAB/Simulink platform, demonstrating the robustness of a proposed FOFPID with an IUPQC controller. The performance of a proposed controller is analyzed through two cases for both feeders. Furthermore, the total harmonic distortions (THD) are calculated for the feeder parameters. The proposed FOFPID with IUPQC controller also maintains stability in a dual feeder. Therefore, the entire response shows the functionality and feasibility of a proposed controller

Application of DSTATCOM for surplus power circulation in MV and LV distribution networks with single-phase distributed energy resources

Single-phase distributed energy resources (DERs), such as rooftop photovoltaic arrays, are usually installed based on the need and affordability of clients without any regard to the power demand of the connected phase of a three-phase system. It might so happen that the power generation in a particular phase is more than its load demand. This may cause a reverse power flow in a particular phase, especially in a three-phase, four-wire distribution system. If now the load demand in the other two phases is more than their respective generations, then these two phases will see a forward power flow, while there will be a reverse power flow in the third phase. This will create severe unbalance in the upstream network. In this paper, a distribution static compensator (DSTATCOM) is used to circulate the excess generation from one phase to the others such that a set of balanced currents flow from or into the upstream network. Two different topologies of DSTATCOM are proposed in this paper for the low and medium voltage feeders. Two different power circulation strategies are developed for this purpose. Furthermore, a suitable feedback scheme is developed for each topology for power converter control. The performance of the proposed topologies and the control schemes for the DSTATCOM is evaluated through computer simulation studies using PSCAD/EMTDC

Power quality enhancement using power balance theory based DSTATCOM

The DSTATCOM (Distributed Static Compensator) is used for current harmonic mitigation, Power Factor Correction (PFC), reactive power compensation, load balancing and neutral current compensation in the Power Distribution System (PDS). In this paper, the power balance theory based DSTATCOM is used for power quality enhancement like current harmonic mitigation, power factor correction (PFC), reactive power compensation, load balancing and neural current compensation and load balancing. A non-isolated star/delta transformer is to reduce dc-link voltage v_(dc) of Voltage Source Converter (VSC) and neutral current compensation. The reference source currents can be extracted quickly by using proposed power balance theory. The proposed power balance theory based DSTATCOM is modeled and simulated using MATLAB/SIMULINK under PFC and ZVR (Zero Voltage Regulation) operations

Power quality improvement based on hybrid coordinated design of renewable energy sources for DC link channel DSTATCOM

This paper presents a comprehensive analysis of power quality for static synchronous compensator on the distribution power system (DSTATCOM) when a different types of energy sources are used to supply the dc link channel of DSTATCOM. These types of power supplies have a different effect on the compensation of DSTATCOM due to operation nature of these sources. The dynamic response of the DSTATCOM has been investigated that produced by individual and hybrid energy sources to evaluate the influence of these sources in terms of time response, compensation process and reduce the harmonics of current for source. Three cases have been considered in this study. First the photovoltaic (PV) cells alone second the battery storage alone and third a hybrid coordinated design between (PV cells with battery storage) is used. A boost Dc-Dc circuit has been connected to a photovoltaic cell with Maximum Power Point Tracking (MPPT) while a Dc-Dc buck-boost circuit is used with a battery. High coordination between PV and battery circuits in the hybrid system is used in order to improve the performance. A synchronous reference frame (SRF) with unit vector has been used to control the STATCOM circuit. The simulation results show that the hybrid design has the superiority response compared to the individual sources

Reliability Improvement of Autonomous Microgrids through Interconnection and Storage

This thesis deals with reliability and power quality improvement in autonomous microgrids. The reliability is improved through the interconnection of storage, intertying two neighbouring microgrids and interlinking of microgrids cluster through a common power exchange highway. The power quality is improved by interconnecting distributed static compensator (DSTATCOM) in the microgrid. All the proposed methods are verified through extensive digital computer simulation using PSCAD

Enhancing radial distribution system performance by optimal placement of DSTATCOM

In this paper, A novel modified optimization method was used to find the optimal location and size for placing distribution Static Compensator in the radial distribution test feeder in order to improve its performance by minimizing the total power losses of the test feeder, enhancing the voltage profile and reducing the costs. The modified grey wolf optimization algorithm is used for the first time to solve this kind of optimization problem. An objective function was developed to study the radial distribution system included total power loss of the system and costs due to power loss in system. The proposed method is applied to two different test distribution feeders (33 bus and 69 bus test systems) using different Dstatcom sizes and the acquired results were analyzed and compared to other recent optimization methods applied to the same test feeders to ensure the effectiveness of the used method and its superiority over other recent optimization mehods. The major findings from obtained results that the applied technique found the most minimized total power loss in system ,the best improved voltage profile and most reduction in costs due power loss compared to other methods