scholarly journals From Hierarchical Control to Flexible Interactive Electricity Services: A Path to Decarbonization

2021 ◽  
Vol 15 ◽  
pp. 1558-1570
Author(s):  
Marija D. Ilic ◽  
Pedro M. S. Carvalho
Keyword(s):  
Power Flow ◽  
Distribution Systems ◽  
Reactive Power ◽  
Hierarchical Control ◽  
Electric Energy ◽  
Specific Model ◽  
Net Energy ◽  
Primary Control ◽  
Interaction Variables ◽  
And Control

We propose to conceptualise electric energy systems as complex dynamical systems using physically intuitive multilayered energy modelling as the basis for systematic diverse technology integration, and control in on-line operations. It is shown that such modelling exhibits unique structure which comes from the conservation of instantaneous power (P) and of instantaneous reactive power ( _Q), (interaction variables (intVar)) at the interfaces of subsystems. The intVars are used as a means to model and control the interactive zoomed-out inter-modular (inter-area, inter-component) system dynamics. Control co-design can then be pursued using these models so that the primary control shapes intVars of its own module by using its own lowlevel detailed technology-specific model and intVar info exchange with the neighbours. As a result, we describe how the proposed approach can be used to support orderly evolution from today’s hierarchical control to a platform enabling flexible interactive protocols for electricity services. The potential for practical use of the proposed concepts is far-reaching and transparent. All that needs to be conceived is that intVar characterising any intelligent Balancing Authority (iBA) is a generalisation of today’s Area Control Error (ACE) characterising net energy balance of a Balancing Authority (BA). An iBA can be any subsystem with its own sub-objectives, such as distributed energy resources (DERs) comprising customers and grid forming microgrids; distribution systems; transmission systems; Independent System Operators (ISOs); and, ultimately, electric energy markets within large interconnection. Several industry problems are described as particular sub-problems of general interactive electricity services. These formulations help one compare models and assumptions used as part of current solutions, and propose enhanced solutions. Most generally, feasibility and stability conditions can be introduced for ensuring feasible power flow solutions, regulated frequency and voltage and orderly power exchange across the iBAs.

Optimal Capacitors Placement of Distribution Systems Using 2nd Order Power Loss Sensitivity Analysis and Hierarchical Clustering

2014 ◽  
Vol 986-987 ◽  
pp. 377-382 ◽  
Author(s):  
Hui Min Gao ◽  
Jian Min Zhang ◽  
Chen Xi Wu
Keyword(s):  
Sensitivity Analysis ◽  
Hierarchical Clustering ◽  
Distribution System ◽  
Power Flow ◽  
Distribution Systems ◽  
Reactive Power ◽  
Digital Simulation ◽  
Second Order ◽  
First Order ◽  
The Impact

Heuristic methods by first order sensitivity analysis are often used to determine location of capacitors of distribution power system. The selected nodes by first order sensitivity analysis often have virtual high by first order sensitivities, which could not obtain the optimal results. This paper presents an effective method to optimally determine the location and capacities of capacitors of distribution systems, based on an innovative approach by the second order sensitivity analysis and hierarchical clustering. The approach determines the location by the second order sensitivity analysis. Comparing with the traditional method, the new method considers the nonlinear factor of power flow equation and the impact of the latter selected compensation nodes on the previously selected compensation location. This method is tested on a 28-bus distribution system. Digital simulation results show that the reactive power optimization plan with the proposed method is more economic while maintaining the same level of effectiveness.

scholarly journals A Hierarchical Control Methodology for Renewable DC Microgrids Supporting a Variable Communication Network Health

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 418 ◽  
Author(s):  
Muhammad Shahid ◽  
Muhammad Khan ◽  
Jianming Xu ◽  
Khurram Hashmi ◽  
Salman Habib ◽  
...  
Keyword(s):  
Power Flow ◽  
Renewable Energy Sources ◽  
Hierarchical Control ◽  
Network Connectivity ◽  
Voltage Regulation ◽  
Monitoring And Control ◽  
Dc Microgrids ◽  
Communication Links ◽  
Microgrid Control ◽  
And Control

The monitoring and control of renewable energy sources (RESs) based on DC (Direct Current) microgrids (DC MG) are gaining much consideration at this time. In comparison with the isolated individual control of converters in a microgrid, DC microgrids provide better voltage regulation and harmonized energy generation/consumption. To address the inherent vulnerability of communication links, robust methods have been proposed that improve the resilience of communication-based control. However, the failure of the communication links in microgrid control layers remains a considerable issue that may lead to one or more nodes being disconnected and operating as a communication island. Such types of communication islanding may cause the unpredictable behavior of the system and further destabilization may lead to a cascaded failure. This paper proposes a fast algorithm to detect and evaluate network connectivity based on the information stored at every node in the form of a look-up table. The control structure has been modified under communication islanding, and a communication connectivity observer is used at every node to detect and address power flow issues under communication islanding. The proposed method has been verified through mathematical analysis, simulation, and experimental results.

scholarly journals Secondary Control for Storage Power Converters in Isolated Nanogrids to Allow Peer-to-Peer Power Sharing

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 140 ◽  
Author(s):  
Eva González-Romera ◽  
Enrique Romero-Cadaval ◽  
Carlos Roncero-Clemente ◽  
Mercedes Ruiz-Cortés ◽  
Fermín Barrero-González ◽  
...  
Keyword(s):  
Power Flow ◽  
Control Method ◽  
Low Voltage ◽  
Hierarchical Control ◽  
Power Converter ◽  
Power Sharing ◽  
Primary Control ◽  
Secondary Control ◽  
Control Loops ◽  
Energy Interchange

It is usual in literature that power sharing among grid-forming sources of an isolated microgrid obeys their energy rating, instead of economic agreements between stakeholders, and circulating energy among them is usually avoided. However, these energy interchanges make strong sense and classical power sharing methods must be reformulated in the context of prosumer-based microgrids. This paper proposes a secondary control method for a prosumer-based low-voltage nanogrid that allows for energy interchange between prosumers, where storage systems, together with PV generators, are the controllable grid-forming sources. A power flow technique adapted to islanded microgrids is used for secondary control algorithm and the whole hierarchical control strategy for the prosumer converter is simulated and validated. This hierarchical control consists of three stages: tertiary control plans the energy interchange among prosumers, secondary obtains different voltage and power setpoints for each of the grid-forming sources, and, finally, primary control guarantees stable voltage and frequency values within the nanogrid with droop rules. Inner control loops for the power converter are also defined to track setpoints and assure stable performance. Simulation tests are carried out, which prove the stability of the proposed methods and the accuracy of the setpoint tracking.

scholarly journals The Optimization of the Location and Capacity of Reactive Power Generation Units, Using a Hybrid Genetic Algorithm Incorporated by the Bus Impedance Power-Flow Calculation Method

2020 ◽  
Vol 10 (3) ◽  
pp. 1034
Author(s):  
Insu Kim
Keyword(s):  
Genetic Algorithm ◽  
Power Generation ◽  
Calculation Method ◽  
Power Flow ◽  
Distribution Systems ◽  
Optimal Power Flow ◽  
Reactive Power ◽  
Hybrid Genetic Algorithm ◽  
Power Flow Calculation ◽  
Flow Calculation

Dynamic and static reactive power resources have become an important means of maintaining the stability and reliability of power system networks. For example, if reactive power is not appropriately compensated for in transmission and distribution systems, the receiving end voltage may fall dramatically, or the load voltage may increase to a level that trips protection devices. However, none of the previous optimal power-flow studies for reactive power generation (RPG) units have optimized the location and capacity of RPG units by the bus impedance matrix power-flow calculation method. Thus, this study proposes a genetic algorithm that optimizes the location and capacity of RPG units, which is implemented by MATLAB. In addition, this study enhances the algorithm by incorporating bus impedance power-flow calculation method into the algorithm. The proposed hybrid algorithm is shown to be valid when applied to well-known IEEE test systems.

scholarly journals Modeling and Control of a Novel Hybrid Power Quality Compensation System for 25-kV Electrified Railway

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3303 ◽  
Author(s):  
Minwu Chen ◽  
Yinyu Chen ◽  
Mingchi Wei
Keyword(s):  
Power Quality ◽  
Power Flow ◽  
Reactive Power ◽  
Compensation System ◽  
Modeling And Control ◽  
Voltage Unbalance ◽  
Hybrid Power ◽  
Traction Power Supply System ◽  
Traction Power Supply ◽  
And Control

The severe power quality problems aroused by the single-phase 25-kV traction power supply system (TPSS), especially for the voltage unbalance (VU) and high-frequency harmonic resonance, have attracted increasing attention nowadays. In this paper, a novel hybrid power quality compensation system, including a power flow controller (PFC) and thyristor-controlled L and C-type filter (TCL-CTF), is proposed. The PFC can be used for VU compensation, and the TCL-CTF can be designed to filter out harmonics as well as compensate reactive power. Furthermore, an optimized compensation strategy is proposed, and the power quality of the TPSS can meet the requirements of the technology standard. Compared with the conventional scheme, the compensation capacity of the PFC can be reduced by 12%, as well as the cost. Finally, the effectiveness of the proposed system is verified by the simulation and experimental results.

A Novel Multi-Functional Grid-Connected Inverter of Renewable Energy Resources

2013 ◽  
Vol 448-453 ◽  
pp. 2191-2194
Author(s):  
Lei Zhou ◽  
Hong Da Liu ◽  
Ming Jie Chen ◽  
Nai Jun Shen
Keyword(s):  
Renewable Energy ◽  
Distribution Systems ◽  
Reactive Power ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
Unit Vector ◽  
Renewable Energy Resources ◽  
Point Of Common Coupling ◽  
Grid Connected Inverter ◽  
And Control

On the basis of analyzing the synthesis application of p-q (instantaneous reactive power) theory and unit vector template, a multi-functional grid-connected inverter (MFGCI) with auxiliary services on power quality enhancement in micro-grid (MG) is presented. The novel control strategy for achieving maximum benefits from these MFGCI when installed in AC MG access to 3-phase 4-wire distribution systems by isolated transformer at the point of common coupling (PCC). This kind of inverter can not only deliver the power generation of renewable energy sources (RESs), but also can perform as active power filter (APF) at their PCC as well as can improve the efficiency of inverter and decrease the hardware investment. Finally, both feasibility and effectiveness of this new topologies and control strategies of MFGCI are verified by PSCAD/EMTDC.

scholarly journals Evaluation of 20 kV Distribution Network Losses In Radial Distribution Systems Due to Distributed Generation Penetration

2021 ◽  
Vol 2129 (1) ◽  
pp. 012085
Author(s):  
H Arnawan ◽  
I Muzamir ◽  
I Y Mohd ◽  
R A R Siti ◽  
S Hadi
Keyword(s):  
Distributed Generation ◽  
Power Flow ◽  
Distribution Systems ◽  
Reactive Power ◽  
Negative Impact ◽  
Distribution Network ◽  
Before And After ◽  
Generation Capacity ◽  
Network Losses ◽  
Increasing Demand

Abstract The installation of distributed generation with renewable energy becomes a solution when the demand for electricity is increasing and electricity generation with fossil energy is increasingly limited. There has been a change in power flow before and after the installation of distributed generation. However there can be a negative impact on the distribution network losses applicable to reactive power flows. There are cases where the distributed generation capacity is greater than the supplied load, resulting in distributed generation operating as a system voltage regulator and requiring reactive power, so that DG will absorb the reactive power from the system. The increasing demand for reactive power in DG also causes an increase in the current flowing in the network, and causes an increase in losses in the network, especially for the losses in reactive power.

scholarly journals Optimal Economic–Environmental Operation of BESS in AC Distribution Systems: A Convex Multi-Objective Formulation

Computation ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 137
Author(s):  
Walter Gil-González ◽  
Oscar Danilo Montoya ◽  
Luis Fernando Grisales-Noreña ◽  
Andrés Escobar-Mejía
Keyword(s):  
Co2 Emissions ◽  
Power Factor ◽  
Power Flow ◽  
Distribution Systems ◽  
Optimal Power Flow ◽  
Pareto Front ◽  
Reactive Power ◽  
Global Optimum ◽  
Multi Objective ◽  
Objective Model

This paper deals with the multi-objective operation of battery energy storage systems (BESS) in AC distribution systems using a convex reformulation. The objective functions are CO2 emissions, and the costs of the daily energy losses are considered. The conventional non-linear nonconvex branch multi-period optimal power flow model is reformulated with a second-order cone programming (SOCP) model, which ensures finding the global optimum for each point present in the Pareto front. The weighting factors methodology is used to convert the multi-objective model into a convex single-objective model, which allows for finding the optimal Pareto front using an iterative search. Two operational scenarios regarding BESS are considered: (i) a unity power factor operation and (ii) a variable power factor operation. The numerical results demonstrate that including the reactive power capabilities in BESS reduces 200kg of CO2 emissions and USD 80 per day of operation. All of the numerical validations were developed in MATLAB 2020b with the CVX tool and the SEDUMI and SDPT3 solvers.

scholarly journals Load Flow Analysis in Hybrid AC-DC Transmission Network

2021 ◽  
pp. 617-624
Author(s):  
Ajith M ◽  
Dr. R. Rajeswari
Keyword(s):  
Power Systems ◽  
Power System ◽  
Transmission Lines ◽  
Power Flow ◽  
Reactive Power ◽  
Short Circuit ◽  
Flow Analysis ◽  
Load Flow ◽  
System Stability ◽  
And Control

Power-flow studies are of great significance in planning and designing the future expansion of power systems as well as in determining the best operation of existing systems. Technologies such as renewables and power electronics are aiding in power conversion and control, thus making the power system massive, complex, and dynamic. HVDC is being preferred due to limitations in HVAC such as reactive power loss, stability, current carrying capacity, operation and control. The HVDC system is being used for bulk power transmission over long distances with minimum losses using overhead transmission lines or submarine cable crossings. Recent years have witnessed an unprecedented growth in the number of the HVDC projects. Due to the vast size and inaccessibility of transmission systems, real time testing can prove to be difficult. Thus analyzing power system stability through computer modeling and simulation proves to be a viable solution in this case. The motivation of this project is to construct and analyze the load flow and short circuit behavior in an IEEE 14 bus power system with DC link using MATLAB software. This involves determining the parameters for converter transformer, rectifier, inverter and DC cable for modelling the DC link. The line chosen for incorporation of DC link is a weak bus. This project gives the results of load flow and along with comparison of reactive power flow, system losses, voltage in an AC and an AC-DC system.

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