Enhancing Transmission Efficiency through Series Compensation: A Case Study Perspective

The voltage stability problem in long-distance transmission systems can be exacerbated by geomagnetic disturbance (GMD) even in middle and low latitude areas where the effects of GMDs are considered to be mild compared to auroral areas. With the high voltage and the long-distance transmission lines, power system in China has to face the voltage instability risk. To clarify and measure the risk from GMD represented by geoelectric field, method for analysis of relationship between voltage stability of the long-distance transmission system and the size and direction of geoelectric field is provided. On the basis of calculation for geomagnetically induced currents (GICs) of power system and the additional reactive power losses of transformer due to GIC, the model of long-distance transmission line affected by geoelectric field is established. To measure the impact on the voltage stability of power system and the sensitivity of voltage to geoelectric field, the voltage stability index and the set of voltage limit violation nodes are proposed and calculated considering different geoelectric field and different initial operation conditions of power system. By taking the Northwest 750 kV power system in China as an example, voltage stability with geoelectric field magnitude from 1 V/km to 10 V/km, direction (0°) from north to south (180°) is analyzed and the voltage stability index is calculated, and the set of voltage limit violation nodes are summarized as well. The results show that the method is feasible and the index can reflect actually the relationship between the long-distance transmission system voltage stability and the geoelectric field, and the set of the voltage limit violation nodes can indicate which nodes are most susceptible to GMD.

Advancements in renewable energy sources (RES) have significantly increased power generation and reduced emissions. Optimally integrating RES into distribution systems can minimize power losses, emissions, and enhance voltage profile and stability. Therefore, determining the optimal location and size of RES is crucial for their effective integration. This paper presents a novel approach for identifying the optimal location and size of a solar power plant (SPP) in a distribution system, considering system power losses, voltage profile, voltage stability, and emissions simultaneously. A simple yet effective methodology combining repeated load flow and fuzzy systems is proposed. Repeated load flow is used to calculate the relevant attributes, while fuzzy decision-making is employed to determine the optimal solution. The effectiveness of the proposed method is demonstrated through its application to the IEEE-33 bus system. The results illustrate that integrating a SPP at the optimal location and size can significantly reduce power losses and emissions while improving voltage profile and stability.

Here we introduce the Power Loss Index (PLI) and Power Stability Index (PSI), for placement of D-STATCOM on a bus, to reduce line losses and improve the voltage profile of the system in consideration. In PLI method, by carrying out load flow, the bus parameters are calculated. The PLI uses the reactive power value of all the buses to find out the optimal placement of D-STATCOM. PSI is developed considering stable node voltages. The proposed algorithm has been tested on a standard IEEE 12-bus radial distribution system in MIPOWER software. MATLAB has been using for comparative analysis using various plots.

Contingency screening and ranking method has gained importance in modern power system and plays a crucial role in its secure operation. This paper proposes Radial Basis Function Network (RBFN) to realize static security assessment of power system using regression module. Newton-Raphson Load Flow (NRLF) is used for load flow analysis and single line outages are considered for pattern generation. Composite Security Index (CSI) is calculated to assess the severity of the system, which considers the combined effect of the limit violations of bus voltages as well as power flow of the transmission lines. After training, module predicts the Composite Security Index and ranks those in descending order based on Composite Security Index. Less number of variables are selected from total variables by Single Ranking and Correlation Coefficient method. The proposed module is applied to IEEE 14, IEEE 30-bus and IEEE 57-bus standard test system, where the testing results prove its performance and robustness for static security assessment of power system. The comparison of ranking obtained by Radial Basis Function Network and the Newton-Raphson Load Flow analysis in terms of time and accuracy is presented. It is found that the proposed model is quick and accurate to predict static security assessment of power system.

In this paper a novel numerical algorithm for locating faults on transmission lines will be presented. The algorithm does not need the line parameters to locate the fault and can locate all fault types, which makes it very different to existing fault location methods. Line parameters are known only approximately and they differ with varying loading and weather conditions, so an algorithm that does not need them will be more accurate, robust and flexible. This will lead to more reliable fault location and faster fault rectification, helping to improve the security and quality of the energy supply. The algorithm requires synchronised data sampling from both ends of the line, this can be achieved using the emerging Synchronized Measurement Technology. As transmission lines become longer to transport energy from remote sources to load centres, series compensation has been found to be an efficient and economical means of increasing transmission line capacity and voltage stability. However, series compensation can have an adverse effect on the line's protection; therefore the aim of this paper is to develop a settings-free fault location algorithm that is unaffected by series compensation. The algorithm was rigorously tested using ATP-EMTP simulations; the results of which are presented in this paper. (5 pages)

Amicrogrid is a combination of clusters of distributed generators connected to fulfill the requirement of dedicated load. A microgrid can be operated with standalone or grid connected mode. A microgrid when operated in standalone mode with a limited voltage and power rating is more likely prone to a serious damage due to its unpredictable faults. Load flow, voltage stability & short circuit analysis of a micro-grid is essential for both design and performance monitoring and to ensure reliable microgrid operations. The faults with a continuously varying in nature affects the normal operation of buses and so to the peripherals associated to the micro-grid. The cause and severity of such faults plays a vital role while designing protection scheme in standalone micro-grid as standalone mode has confined generation. In this paper, electrical model of a 52.3 kW Photo-voltaic based micro-grid is developed on Electrical Transient Analysis Program (ETAP) and various transient conditions such as load flow, loss of DG & short circuit analyses are performed. A detailed short circuit analysis puts light on various short circuit conditions and provides useful analysis. ETAP is the most comprehensive analysis platform for the design, simulation, operation, and automation of generation, distribution, and industrial power systems. ETAP also provides the industry leading transient analysis of power system and micro-grid so chosen for this transient analysis study. A short circuit analysis is calculated based onIEC Std. 60909 using ETAP. This paper presents a simulated model of micro-grid with actual system oriented results and analyzes responses of system during fault conditions and various contingencies.

High voltage direct current (HVDC) transmission offers several operation advantages over high voltage alternating current (HVAC) transmission systems. HVDC transmission lines have no frequency and hence minimal problems of harmonics, oscillations or transients; they actually damp out transients with effective controllers. Precise and fast power control in either direction is easier to achieve in HVDC than HVAC systems as dc power is minimally affected by reactance. This curtails system instability, cascading effect or voltage collapse. The ease of power flow control in HVDC lines makes it easy to achieve the maximum power and thermal capacity of transmission lines. It is also simple to control active power transfer at a predetermined level or even to modulate this to improve system damping. For weak AC grids, voltage source converter (VSC) based HVDC systems offer better controllability and grid flexibility for integrating intermittent renewable energy sources such as wind and solar-power. HVDC systems offer technical advantages: all angular stability problems disappear and even connection of systems at different frequency is feasible. The problems of cable charging current are eliminated. Thus cables can readily be used for underwater crossings. HVDC is the established technology of choice for long distance transmission and subsea electrical power transmission systems. In this paper, an investigation of voltage stability margin on Eskom high voltage eastern grid is carried out. Using the Newton Raphson iterative method, the impact of HVDC link controller and transformer tap changers on voltage stability were evaluated on Athene substation of Eskom eastern grid, an area of rapid load growth. Results obtained show that by introducing HVDC line, transmission capacity is enhanced, with lower line losses and improved voltage profile. Simulations were carried out using DigSILENT PowerFactory.

Voltage stability is an important issue in power system operation. Flexible AC transmission systems, so-called FACTS devices, help to improve voltage stability and minimize real power losses. The effectiveness of FACTS devices depend on their proper location and rating. This paper presents a method, based on line flow sensitivity factors such as bus voltage stability index and line voltage stability index, to find suitable locations of multi-type FACTS devices. Also this paper proposes an application of particle swarm optimization (PSO) and harmony search algorithm (HSA) in optimizing the rating of FACTS devices. The proposed approaches are evaluated with three different objective functions namely, minimization of real power loss, improvement of voltage profile and enhancement of voltage stability. The performance of proposed methods is analyzed on IEEE 14 bus system by implementing FACTS devices such as static var compensator (SVC), thyristor controlled series capacitor (TCSC) and unified power flow controller (UPFC).The analysis shows that there is a reduction in real power loss and improvement in voltage stability and voltage profile of the system after employing FACTS devices. It also shows that both real power loss and bus voltage stability index (BVSI) have been reduced more with FACTS ratings obtained from PSO than with that from HSA.

The typical receiving-end systems in China are continuously connected with HVDC transmission lines, which changes the traditional grid form and makes the voltage stability problem prominent. How to understand the relation among voltage stability, power grid strength and equipment control is the key to grasp the mechanism of voltage stability and improve the control to avoid the systems entering into static voltage instability and transient voltage instability. In this paper, the relation among the transmitted active power, the voltage at the equipment infeed point and the current of AC system is studied, the relation among the voltage stability and the power grid strength and the control logic of the equipment is explained. Then, the influence rules of line reactance and equipment reactive power on the power limit trajectory (PLT) is studied. In the end, based on the power limit trajectory determined by line reactance, the simulation results of PSCAD/EMTDC showed that the improved DC control method can improve the voltage stability, and the theory in this paper has a certain practical guiding significance.

Optimal distribution network reconfiguration (DNR), distributed generations location and sizing (DGs-LS), tap changer adjustment (TCA), and capacitors bank location and sizing (CAs-SL) are different methodologies used to reduce loss and enhance the voltage profile of distribution systems. DNR is the process of changing the network topography by changing both sectionalized and tie switch states. The optimal location looks to find the optimal setting of the DG and CA within the distribution network. Optimal size seeks to find the optimal output generation of both DG and CA. The TCA looks to find the optimal position for TC. These methods are challenging optimization problems and resort to meta-heuristic techniques to find a globally optimal solution. This paper presents a new methodology with which to simultaneously solve the problem of DNR, DGs-LS, TCA, and CAs-SL in distribution networks. This work aims to minimize active and reactive power losses, including voltage profile improvement using a multi-objective decision approach. The firefly algorithm (FA) and analytic hierarchy process (AHP) are used to optimize the fitness function and determine the function weight factors through the use of MATLAB software. Several scenarios were considered on the IEEE 69-bus network. In terms of active power and reactive losses, reductions in the test system of 96.16% and 92.7%, respectively, were achieved, evidencing the positive impact of the proposed methodology on distribution networks.

The application of optimal reactive power flow (ORPF) problem to the NB (New Brunswick) Power company are presented. The potential benefits and the real-time implementation problems of ORPF are discussed. The execution of ORPF program for NE Power network has shown two major benefits: (1) the improvement in the voltage profile and voltage stability, and (2) the savings in active power loss. The improvement in voltage profile can cause less violations and a more stable system from the voltage point of view. A reduction in active power loss gained from ORPF can save a significant amount of money. The total saving for year 1995 predicted in study was in excess of $1100000, and this was supported by the real-time test. These savings can be gained simultaneously with the improvement of the voltage profiles.

The demand of quality & reliable power by the consumers is increasing day by day in a tremendous manner. Everyone needs good quality of power with out any disturbances or interruptions. Also due to large no of present day consumers, the power system needs a boosting mechanism in order to capitalize the complexity of power system. So a reliable technology of FACTS(Flexible AC Transmission System) is introduced in the power system to enhance the flexibility of power grids. FACTS devices are power electronics based controllers & improve the system performance by shunt or series compensation. They injects or absorbs reactive power to/from the power system at the time of need. In this paper a shunt type of FACTS controller such as SVC(Static Var Compensator) is considered for stability enhancement & loss minimization in a nine bus power system. SVC consists of TCR(Thyristor Controlled Reactor), TSC(Thyristor Switched Capacitor), a fixed capacitor connected parallel to the line & filter elements for harmonic reduction. Here the enhancement of voltage stability & loss minimization is analyzed in terms of voltage magnitude variation & overall real & reactive power losses at each bus w.r.t the location of installation of SVC. Firstly Load flow study carried out for an uncompensated system & then for SVC compensated system by changing the location of installation of SVC from bus1 to bus9. And also thereby specifying the optimal location of SVC by analyzing the load flow data in terms of voltage magnitude variation & overall losses. All the performance analysis has been performed using MATLAB/SIMULINK software.

Voltage stability analysis is the major concern in order to operate any power system safely. In this context considerable research work has been carried out to improve the voltage stability. FACTS devices can used for controlling power flow, transmission voltage, improving voltage profile, and reducing reactive losses. In this paper two different FACTS devices have been selected to place in suitable location to improve voltage stability in power system. The mathematical model of the power system equipped with a Static VAR Compensator (SVC) and Static synchronous compensator (STATCOM) separately is systematically derived and the parameters of the shunt FACTS are modeled into the power flow equations and used in the control strategy. The two models of FACTS are developed for the IEEE 30-bus system and implemented in Newton-Raphson load flow algorithm in order to control the voltage of the bus to which the shunt FACTS is connected. In this study a MATLAB written program is used for the solution of power flow problems and calculate voltages, active and reactive power at each bus of IEEE 30-bus system.

This road map aims to provide guidelines for installing up to 45,000 SIP systems with pump ratings ranging from 4 kilowatts (kW) to 25 kW that would add up to 1,000 megawatt peak (MWp) of solar capacity to the country. These SIP systems would displace the consumption of 300,000 tons of diesel fuel annually, avoiding 900,000 metric tons of carbon dioxide equivalent (MtCO 2 e) emissions every year. The target number of SIP systems aims to replace diesel pumps irrigating up to 400,000 hectares of land and serving more than 1.3 million farmers. The indicative breakdown per type of SIP system proposed is 15,000 solar low-lift pumps for irrigation with surface water, 2,000 solar deep tube wells, and 28,000 shallow tube wells for groundwater irrigation. The proposed number of solar pumps will produce surplus electricity of 480 gigawatt-hours (GWh) per year for export to the grid, almost 1% of Bangladesh's current total electricity generation. This would provide a regular income to farmers. Studies conducted for the Power Division of the Ministry of Power, Energy and Mineral Resources in 2021 concluded that load flow, voltage stability, frequency response, and angular stability for 10% and 25% integration of variable renewable energy (VRE), such as solar and wind energy, do not negatively affect the grid, so the grid would remain stable. Since this road map proposes the integration of much lower shares of VRE, the conclusion is that the road map's rollout does not represent any significant risk to the stability of the grid.

The intuition of the power companies is to supply quality power to the consumers with reduced line losses. Reduction of transmission and Distribution line losses is a great challenge for most of the developing countries. This paper demonstrates the network reconfiguration in a practical low voltage Indian utility Distribution Feeder. Various configurations are suggested and the real power losses are computed using General Algebric Modeling System (GAMS), Mixed Integer Linear Programming (MILP) CPLEX solver. Load balancing is done for mitigation of voltage profile at the highly loaded nodes. Load flow analysis is performed through Forward / Backward Sweep analysis, which is more suitable for the radial system. Real power loss and voltage at nodes are compared and presented before and after network reconfiguration. This paper emphasizes the importance of network reconfiguration for developing countries like India.