Application of diverse FACTS in AGC of multi-area interconnected energy systems

This article presents the simple and effective control design for active power regulation of modern energy delivery system. As an energy delivery system experiences the demand changes as per the demand of the modern energy users due to which the system frequency is highly troubled and fluctuating. To balance such demand changes and to stable the system occurrence fluctuations, the thyristor control phase shifter (TCPS) in synchronisation with super conducting magnetic energy storage (SMES) or TCPS in coordination with capacitive energy storage (CES) based model predictive control (MPC) technique are proposed. SMES-SMES and CES-CES configurations are also tested for energy delivery system. The effectiveness of the proposed system regulator design are guaranteed by analyzing the transient system performance under varying load pattern, sinusoidal load change and for system non-linearities. A comparative performance analysis between TCPS-SMES, TCPS-CES, SMES-SMES and CES-CES based MPC of energy system are tested and presented

A simplified control scheme for electric vehicle- power grid circuit with DC distribution and battery storage systems

Abstract: Direct current (DC) system is becoming the major trend for future internal power grid of electric vehicles (EVs). Since DC power grid system has a different nature to conventional alternating current (AC) grid system, appropriate design of the controller for EV- grid circuit is mandatory. In this paper, an EV employing a pure DC grid circuit with battery storage system (BSS) is considered as a study case. To enable a more efficient use of BSS, a flyback DC-DC converter for batteries charger/or discharger strategy is selected, which satisfy the power flows requirements. The dynamic and control performances of the combined system, i.e. “BSS- flyback DC-DC converter- connected to a DC motor”, is investigated in terms of voltage/ current signal fluctuations. The small-signal based control method is used, which limits the small-signal variations to about zero. To verify the effectiveness of the control strategy several simulations are done using Matlab. The simulation results illustrate the performances obtained

A review on DC collection grids for offshore wind farms with HVDC transmission system

Abstract: Traditionally, the internal network composition of offshore wind farms consists of alternating current (AC) collection grid; all outputs of wind energy conversion units (WECUs) on a wind farm are aggregated to an AC bus. Each WECU includes: a wind-turbine plus mechanical parts, a generator including electronic controller, and a huge 50-or 60-Hz power transformer. For a DC collection grid, all outputs of WECUs are aggregated to a DC bus; consequently, the transformer in each WECU is replaced by a power converter or rectifier. The converter is more compact and smaller in size compared to the transformer. Thus reducing the size and weight of the WECUs, and also simplifying the wind farm structure. Actually, the use of offshore AC collection grids instead of offshore DC collection grids is mainly motivated by the availability of control and protection devices. However, efficient solutions to control and protect DC grids including HVDC transmission systems have already been addressed. Presently, there are no operational wind farms with DC collection grids, only theoretical and small-scale prototypes are being investigated worldwide. Therefore, a suitable configuration of the DC collection grid, which has been practically verified, is not available yet. This paper discussed some of the main components required for a DC collection grid including: the wind-turbine-generator models, the control and protection methods, the offshore platform structure, and the DC-grid feeder configurations. The key component of a DC collection grid is the power converter; therefore, the paper also reviews some topologies of power converter suitable for DC grid applications

E Effets de la dose d’urée et de la fréquence de sarclage sur le rendement et l’efficience d’utilisation de l’azote chez le maïs (Zea mays L.) dans l’hinterland de Kolwezi

L’objectif de l’étude était d’analyser l’influence de la dose d’urée et de la fréquence de sarclage sur l’efficience d’utilisation de l’azote (NUE) et le rendement du maïs dans les conditions écologiques de Kolwezi. Pour y arriver, un essai a été établi en split plot comprenant 2 facteurs, la dose d’urée avec quatre modalités (0 ; 200 ; 300 et 400 kg d’urée.ha-1) et la fréquences de sarclage avec trois modalités (0 ; 1 et 2 sarclages). Après la récolte du maïs sec et le pesage, deux types d’échantillons composites ont été constitués par traitement (un échantillon pour les parties végétatives et un autre pour les graines, soit un total de 24 échantillons composites) et amenés au laboratoire pour analyse de la teneur en azote total par la méthode Kjeldahl. Les résultats obtenus ont montré qu’a l’exception de l’efficience de prélèvement, la dose d’urée a eu une influence très positive sur tous les paramètres d’efficience d’utilisation d’azote (prélèvement d’azote, efficience physiologique, efficience de production) ainsi que sur le rendement en grains du maïs. En revanche, la fréquence de sarclage n’a eu aucun effet sur tous les paramètres d’efficience et le rendement du maïs. Cependant, sa combinaison avec la dose d’urée a seulement influencé l’efficience physiologique ; les autres paramètres étant restés similaires. L’apport de la dose de 200 kg d’urée.ha-1 en combinaison avec un seul sarclage se sont révélés des pratiques non seulement productives, mais aussi optimales, rentables et moins polluantes c’est-à-dire recommandables. Cette étude met à la disposition des producteurs de maïs des pratiques culturales appropriées capables d’améliorer significativement le rendement et la marge bénéficiaire tout en limitant les pertes d’azote

Load Profile and Load Flow Analysis for a Grid System with Electric Vehicles Using a Hybrid Optimization Algorithm

As they become more widespread, electric vehicles (EVs) will require more electricity to charge. It is expected that a range of grid transportation solutions that complement one another and considerable transmission infrastructure changes will be needed to achieve this goal. Strategic planning and control, including economic models and strategies to engage and reward users, can reduce energy loss on the power network. This would eliminate grid upgrades. Bidirectional charging of EVs can help transmission systems cope with EV allocation. Power loss and voltage instability are the transmission network’s biggest issues. Adding EV units to the transmission network usually solves these problems. Therefore, EVs need the right layout and proportions. This study determined where and how many radial transmission network EVs there should be before and after the adjustment. To discover the best EV position and size before and after the dial network modification, a hybrid genetic algorithm for particle swarm optimization (HGAIPSO) was utilized. Electric vehicles coordinated in an active transmission network reduce power losses, raise voltage profiles, and improve system stability. Electric vehicles are responsible for these benefits. The simulation showed that adding EVs to the testing system reduced power waste. The system’s minimum bus voltage likewise increased. The proposed technology reduced transmission system voltage fluctuations and power losses, according to the comparison analysis. The IEEE-30 bus test system reduced real power loss by 40.70%, 36.24%, and 42.94% for the type A, type B, and type C EV allocations, respectively. The IEEE-30 bus voltage reached 1.01 pu

Power Loss Minimization and Voltage Profile Improvement by System Reconfiguration, DG Sizing, and Placement

A number of algorithms that aim to reduce power system losses and improve voltage profiles by optimizing distributed generator (DG) location and size have already been proposed, but they are still subject to several limitations. Hence, new algorithms can be developed or existing ones can be improved so that this important issue can be addressed more appropriately and effectively. This study proposes a reconfiguration methodology based on a hybrid optimization algorithm, consisting of a combination of the genetic algorithm (GA) and the improved particle swam optimization (IPSO) algorithm for minimizing active power loss and maintaining the voltage magnitude at about 1 p.u. The buses at which DGs should be injected were identified based on optimal real power loss and reactive power limit. When applying the proposed optimization algorithm for DGs allocation in power system, the search space or number of iterations was reduced, increasing its convergence rate. The proposed reconfiguration methodology was test in an IEEE-30 bus electrical network system with DGs allocations and the simulations were conducted using MATLAB software compared to other optimization algorithms, such as GA, PSO, and IPSO, the combination of GA and IPSO or Hybrid GA & IPSO (HGAIPSO) method has a smaller number of iterations and is more effective in optimization problems. The effectiveness of the proposed HGAIPSO has been tested on IEEE-30 bus network system with DGs allocations, and the obtained test results have been compared to those from other methods (i.e., GA, PSO, and IPSO). The simulation results show that the proposed HGAIPSO can be an efficient and promising optimization algorithm for distribution network reconfiguration problems. The IEEE-30 bus test system with DGs integrated at various location revealed reductions in overall real power loss of 40.7040%, 36.2403%, and 42.9406% for type 1, type 2, and type 3 DGs allocation, respectively. The highest bus voltage profile goes to 1.01 pu in the IEEE-30 bus

Voltage Rise Regulation with a Grid Connected Solar Photovoltaic System

Renewable Distributed Generation (RDG), when connected to a Distribution Network (DN), suffers from power quality issues because of the distorted currents drawn from the loads connected to the network over generation of active power injection at the Point of Common Coupling (PCC). This research paper presents the voltage rise regulation strategy at the PCC to enhance power quality and continuous operation of RDG, such as Photovoltaic Arrays (PVAs) connected to a DN. If the PCC voltage is not regulated, the penetration levels of the renewable energy integration to a DN will be limited or may be ultimately disconnected in the case of a voltage rise issue. The network is maintained in both unity power factor and voltage regulation mode, depending on the condition of the voltage fluctuation occurrences at the PCC. The research investigation shows that variation in the consumer’s loads (reduction) causes an increase in the power generated from the PVA, resulting in an increase in the grid current amplitude, reduction in the voltage of the feeder impedance and an increase in the phase voltage amplitude at the PCC. When the system is undergoing unity power factor mode, PCC voltage amplitude tends to rises with the loads. Its phase voltage amplitude rises above an acceptable range with no-loads which are not in agreement, as specified in the IEEE-1547 and Southern Africa grid code prerequisite. Incremental Conduction with Integral Regulator bases (IC + PI) are employed to access and regulate PVA generation, while the unwanted grid current distortions are attenuated from the network using an in-loop second order integral filtering circuit algorithm. Hence, the voltage rise at the PCC is mitigated through the generation of positive reactive power to the grid from the Distribution Static Compensator (DSTATCOM), thereby regulating the phase voltage. The simulation study is carried out in a MATLAB/Simulink environment for PVA performance

Power Loss Minimization and Voltage Profile Improvement by System Reconfiguration, DG Sizing, and Placement

A number of algorithms that aim to reduce power system losses and improve voltage profiles by optimizing distributed generator (DG) location and size have already been proposed, but they are still subject to several limitations. Hence, new algorithms can be developed or existing ones can be improved so that this important issue can be addressed more appropriately and effectively. This study proposes a reconfiguration methodology based on a hybrid optimization algorithm, consisting of a combination of the genetic algorithm (GA) and the improved particle swam optimization (IPSO) algorithm for minimizing active power loss and maintaining the voltage magnitude at about 1 p.u. The buses at which DGs should be injected were identified based on optimal real power loss and reactive power limit. When applying the proposed optimization algorithm for DGs allocation in power system, the search space or number of iterations was reduced, increasing its convergence rate. The proposed reconfiguration methodology was test in an IEEE-30 bus electrical network system with DGs allocations and the simulations were conducted using MATLAB software compared to other optimization algorithms, such as GA, PSO, and IPSO, the combination of GA and IPSO or Hybrid GA & IPSO (HGAIPSO) method has a smaller number of iterations and is more effective in optimization problems. The effectiveness of the proposed HGAIPSO has been tested on IEEE-30 bus network system with DGs allocations, and the obtained test results have been compared to those from other methods (i.e., GA, PSO, and IPSO). The simulation results show that the proposed HGAIPSO can be an efficient and promising optimization algorithm for distribution network reconfiguration problems. The IEEE-30 bus test system with DGs integrated at various location revealed reductions in overall real power loss of 40.7040%, 36.2403%, and 42.9406% for type 1, type 2, and type 3 DGs allocation, respectively. The highest bus voltage profile goes to 1.01 pu in the IEEE-30 bus

Some of the design considerations in power generation from offshore wind farms

The global efforts to reduce carbon emissions from power generation have favoured renewable energy resources such as wind and solar in recent years. The generation of power from the renewable energy resources has become attractive because of various incentives provided by government policies supporting green power. Among the various available renewable energy resources, the power generation from wind has seen tremendous growth in the last decade. This article discusses various advantages of the upcoming offshore wind technology and associated considerations related to their construction. The conventional configuration of the offshore wind farm is based on the alternative current internal links. With the recent advances of improved commercialised converters, voltage source converters based high voltage direct current link for offshore wind farms is gaining popularity. The planning and construction phases of offshore wind farms, including related environmental issues, are discussed here

Modelling and control of a VIENNA smart rectifier-I for wind power systems integrated under transient conditions

An improved topology with a fault ride through (FRT) capability when subjected to a DC-link fault-based wind power plant (WPP) employing a Vienna active rectifier-I is proposed in this paper. The proposed system is capable of mitigating fault occurring on the DC-link side using the PWM-controller technique implemented on the Vienna active rectifier. FRT capability analysis is conducted in this paper, simulation results demonstrate the suitability of the control strategy. Actually, use of proposed wind energy conversion unit (WECU) topology has led to the improvement of system stability by maintaining constant output voltage. Furthermore, the WECU integrating Vienna active rectifier-I is also proven as a feasible technology that can be employed in a large-scale WPP or renewable power generations to realize technical and economical efficient grids integration with high voltage direct current (HVDC) transmission systems.http://www.springer.com/journal/40866pm2020Electrical, Electronic and Computer Engineerin