Modified Chameleon Swarm Optimization Algorithm to Improve the Power System Stability

In this paper, a new switching table is presented for direct power control (DPC) of three-phase PWM rectifiers. The proposed switching table is synthesized by analyzing the instantaneous active and reactive power correction. For this reason, and based on the sign and magnitude of the change in instantaneous active and reactive power, the best converter switching state allowing smooth control of active and reactive power simultaneously during each sector is selected. The dc-bus voltage is maintained at the required level by controlling active power to be constant and equal to its reference value. The unity power factor (UPF) operation of the converter is achieved by maintaining the reactive power zero during all sectors. Simulation and experimental results have proven that the proposed DPC is much better than the classical one and verify the validity and performance of the presented DPC.

<p>Doubly Fed Induction Generator (DFIG) needs to get adopted to change in wind speeds with sudden change in reactive power or grid terminal voltage as it is required for maintaining synchronism and stability as per modern grid rules. This paper proposes a controller for DFIG converters and optimal tip speed ratio based maximum power point tracking (MPPT) for turbine to maintain equilibrium in rotor speed, generator torque, and stator and rotor voltages and also to meet desired reference real power during the turbulences like sudden change in reactive power or voltage with concurrently changing wind speed. The performance of DFIG is compared when there is change in wind speed only, changes in reactive power and variation in grid voltage along with variation in wind speed.</p>

In this paper, the modelling of the entire VSC-HVDC system is presented based on d-q axis decomposition and state space modelling is formulated for analysis. Eigenvalues analysis is used for optimal tuning of PI controller based on PSO technique. The system is simulated under most of the frequently occurring faults and abnormal operating conditions such as three-phase fault, parameter variation, frequency variation and change in active and reactive power, change in short circuit ratio and bus voltage reduction and change in converter parameters through MATLAB simulation. The results are presented for the proposed controller with comparison to conventional PI controller under various fault condition.

This paper presents a hybrid method of active power and reactive power control strategy with Quasi Z-source inverter (QZSI) in single phase grid connected photovoltaic (PV) systems. The maximum power from the PV panel is extracted and most of it is supplied as active power to the grid. The major portion of required reactive power exchange to the grid is done by means of thyristor switched capacitor (TSC) and thyristor switched reactor (TSR) to improve the generation capacity of the PV system. In the proposed topology inverter shares the minimum reactive power and large change in reactive power will be delivered/absorbed by the TSC-TSR to get smoother operation in reactive power control. The DC voltage controller and the AC current controller is discussed in brief. The mathematical analysis for grid synchronization method is presented in detail. The control algorithm for active power and reactive power is analyzed and discussed in the paper. The simulation results are shown for validating the proposed concept.

When some household appliances are running, the electrical quantities such as active power and reactive power will change slowly for a long time, which will affect the feature extraction of event-based non-intrusive load identification, resulting in low accuracy of load identification results. In view of this situation, a feature extraction method is proposed. Its core idea is that there is a certain law in the change of active power and reactive power in a very short time, and the curve can be fitted to speculate the values of these electrical quantities in the next time, so as to eliminate the influence. Based on this, a feature extraction method applied to non-intrusive load identification is realized. The test results show that this method can effectively improve the accuracy of non-intrusive load identification feature extraction data, and has good application value.

For stable operation of a power system reliable control of active & reactive power is necessary. Voltage source converter based HVDC system bears the advantages of being able to change the control strategy immediately with respect to the active and reactive power changes. In this paper a function based fuzzy control system is proposed for the control of active power, DC voltage at converter station and voltage at inverter station. Basically two input one output methodology based fuzzy logic controller has been proposed. The basic features of proposed system used in VSC based HVDC systems are: 1) only two rule base system is used.2) all controllers are not self correcting. At both stations error and change in error have been taken as input to the controller. Design of high pass filter with FFT analysis has also been proposed for a better dynamic performance of the function based fuzzy controller. Computer simulation using Simulink gives clear result of the performance of the proposed controller.

A new SPARLS algorithm for tuning power system stabilizer

The reactive power is the background power without which the active power cannot be transmitted in the power systems. In the modern power system, the reactive power pricing is considered as essential in order to maintain the voltage in the transmission line. The modern power system is the grid that functions with smart innovative technological system that provides flexibility, efficiency and availability for the users. The smart grid uses the Internet of Things (IoT) technology to identify and provides the requirement of system reactive power for reactive power pricing. The IoT based wireless communication platform significantly reduces the latency and provides better accuracy. The system requirements for reactive power are optimally dispatched by the generator and other reactive power provider using optimization algorithm like Self Balanced Differential Evolution. Here the analytics and opportunities of smart grid for reactive power service are discussed using 62 bus Indian Utility System (IUS).

Critical Boundary Index (CBI) based on active and reactive power deviations

Doubly fed induction generator (DFIG) needs to get adapted to situations like rapid change in wind speed and sudden requirement for grid disturbances to meet modern grid rules. The paper explains the design of controllers for MPPT algorithm for the turbine, DFIG converters, and sensorless rotor speed estimation. These intelligent controllers are used to maintain equilibrium in rotor speed, generator torque, and stator and rotor voltages. They are also designed to meet desired reference real and reactive power during the turbulences like sudden change in reactive power or voltage with concurrently changing wind speed. The turbine blade angle changes with variations in wind speed and direction of wind flow and improves the coefficient of power extracted from turbine using MPPT algorithm. Rotor side converter (RSC) helps to achieve optimal real and reactive power from generator, which keeps rotor to rotate at optimal speed and to vary current flow from rotor and stator terminals. For tracking reactive power demand from grid and in maintaining synchronism when grid voltage changes due to fault at a very faster and stable way Grid side converter (GSC) is helpful. Rotor speed is estimated using stator and rotor flux estimation algorithm. Parameters like stator and rotor voltage, current, real, reactive power, rotor speed, and electromagnetic torque are studied using MATLAB simulation. The performance of DFIG is compared when there is in wind speed change only; alter in reactive power and variation in grid voltage individually along with variation in wind speed.

This paper proposes a new sensitivity factor, Jacobian Based Distribution Factor (JBDF), to solve the real-time line flow calculation problem. It is derived from the Jacobian matrix of the base case Newton Raphson power flow solution, and kept constant during real-time line flow calculation. Differing from the well-known distribution factors, such as Generation Shift Distribution Factor (GSDF), Generalized Generation Shift Distribution Factor (GGDF) and Z-Bus Distribution Factor (ZBD), it reflects the changes of active and reactive power in each bus. When the loading conditions change from the base case loads, either conforming or non-confirming changes in real and reactive power, it can rapidly and precisely compute the active line flows without any iterations. The proposed JBDF method is tested on the IEEE 14-Bus System. The numerical simulation results demonstrate the proposed method is very accurate and rapid in computation. It is highly suitable for real-time line flow calculation.

Son zamanlarda, artan enerji talebi ve yenilenebilir enerji kaynaklarının (YEK) elektrik güç sistemlerinde yer almasıyla, enterkonnekte güç sistemlerinde frekans ve gerilim kararlılığının önemi artmaktadır. Modern güç sistemlerinde tüketiciye kaliteli, sürekli ve kararlı elektrik enerjisi iletimi sağlanmalıdır. Güç sistemlerindeki ani yük değişimlerinde güç üretimi ile yük talebi arasındaki uyumsuzluk, üretim bölgeleri arasındaki frekansta istenmeyen salınımlara neden olur. Sistemdeki frekans salınımlarını minimize etmek için yük frekans kontrolü (YFK) uygulanır. Sistemdeki salınımları bastırmak için kullanılan denetleyiciler, istenen sistem kriterleri doğrultusunda tatmin edici bir şekilde çalışmalıdır. Bu bağlamda PID ve PID+DD denetleyici yapılarından yararlanılmıştır. Denetleyici parametrelerinin optimizasyonunda literatürde sunulan GBO, BSA ve BKA algoritmaları kullanılmıştır. YFK problemi, termal, hidroelektrik, gaz, rüzgar ve dizel enerji sistemlerini içeren çok kaynaklı tek alanlı test sisteminde incelenmiştir. Test sisteminin doğrusalsızlığını artırmak için kazan dinamiği yapısı kullanılmıştır. Optimizasyon işlemi sonucunda algoritmaların denetleyici parametrelerini optimize etme başarısı kendi içinde değerlendirilmiş ve BSA algoritmasının diğer algoritmalara göre daha başarılı olduğu görülmüştür.

The utilization of renewable energy sources for energy transition is gaining significant popularity due to pollution control and other environmental benefits. To move toward green energy generation, the integration of renewable energy sources with the existing conventional grid plays a key role. The performance of a modern interconnected power system, particularly with a high penetration of renewable energy sources, is significantly impacted by power system oscillations. Flexible Alternating Current Transmission System (FACTS) devices are recommended to improve control framework performance, and the power system stabilizer is the customary controller for damping such oscillations. FACTS offer a powerful strategy as they can control transport voltage, transmission line impedance, and power flows. This paper presents an efficient control scheme that combines four FACTS controllers: the static VAR compensator for controlling reactive power in control frameworks, the unified power flow controller for managing active and reactive power flows on transmission lines, the static synchronous compensator for maintaining system voltage stability, and the static synchronous series compensator for controlling transmission line impedance. To address the challenges posed by the variability of renewable energy sources such as wind and solar, the ant colony optimization algorithm is employed to optimally tune the controllers’ parameters. By generating controlled voltage and interfacing with the transmission line, these controllers enhance system stability, even under fluctuating renewable energy inputs. The IEEE 30-Bus system was used for simulation and control design, demonstrating the effectiveness of this approach in damping inter-area oscillations and improving the stability and resilience of a renewable-energy-integrated power system.

Reliable and efficient power systems operation requires voltage control as well as minimal reactive power flow between a load and the grid. To achieve this objective, reactive power compensating devices are typically utilized. In modern power systems, the synchronous static compensator (STATCOM) is primarily used for reactive power control, both in distribution and transmission lines. This study presents the modeling and simulation of a STATCOM based on a voltage source converter. Simulations are performed for both single phase and three phase power systems. Furthermore, two control techniques, utilizing Proportional Integral (PI) as well as Proportional Resonant (PR) controllers are explored. The PR controller presents several advantages compared to the PI controller. Simulation results show that in both cases, the STATCOM, connected in shunt with the load either provides reactive power to the load, or absorbs reactive power from the load. Thus, net reactive power transfer from the grid to the load is zero. The grid provides only active power, thus keeping the power factor to almost unity.

Maintaining of optimal voltage level in the whole system and on substation in particular is a task of utmost importance and its execution will allow us to improve quality of generated energy (GE) and to decrease losses during transition. Nowadays execution of that task is performed by concurrent reactive power compensation (CRPC) and voltage regulation (VR) in addition to the traditional regulation systems, which are not always perform their functions properly and that in its turn results in a simultaneous work both in generating and consuming of reactive power modes - work in “reverse phase”. Furthermore, existing systems do not take into account initial data of the equipment’s current state which leads to proportional wearing of one RPC comparatively of another installed on the same substation. If change of schematicregime situation occurs power flows of active and reactive power change and they affect the voltage change in nodes. In result regulator’s parameters become irrelevant which can result in insufficient regulation qualities – decrease of stability margin and unsatisfactory GE’s quality.Considering all mentioned above, nowadays there is a problem of actualization of adjusting regulator’s settings. This paper presents a description of a relevant regulator’s parameters determination method by identification of control object and dynamically adjusting regulator’s parameters.