Improve Power System Stability Research Articles

Fractional‐order lead‐lag compensator‐based multi‐band power system stabiliser design using a hybrid dynamic GA‐PSO algorithm

Power system stabilisers (PSSs) are supplementary controllers connected to the excitation system of synchronous generators to damp electromechanical oscillations. Multi-band PSSs are reported as advanced PSSs with the ability to damp out all oscillation modes present in the power systems. This study presents the design of a robust fractional-order multi-band power system stabiliser (Fo-MBPSS) using a meta-heuristic hybrid algorithm for dynamic stability improvement of multi-machine power systems. The large bandwidth, memory effect and flat phase contribution in the frequency response of fractional-order controllers are exploited to make the Fo-MBPSS perform well against a wide range of system uncertainties. The parameter tuning problem of Fo-MBPSS is transformed to an optimisation problem that is solved using a hybrid algorithm by combining a dynamic genetic algorithm (DGA) with a standard particle swarm optimisation (PSO) algorithm. The performance of the proposed DGA-PSO-Fo-MBPSS is evaluated through eigenvalue analysis, non-linear time-domain simulations and some performance indices, in two different multi-machine systems under different loading conditions and disturbances. The results are compared with PSO-based conventional MBPSS and PSO based Fo-MBPSS (PSO-Fo-MBPSS) to establish the fractional parameter effect on the improvement of the system dynamic response and the relevance of the proposed hybrid optimisation technique in achieving robustness.

Stability Improvement of DC Power Systems in an All-Electric Ship Using Hybrid SMES/Battery

As the capacity of all-electric ships (AESs) increases dramatically, the sudden changes in the system load may lead to serious problems, such as voltage fluctuations of the ship power grid, increased fuel consumption, and environmental emissions. In order to reduce the effects of system load fluctuations on system efficiency, and to maintain the bus voltage, we propose a hybrid energy storage system (HESS) for use in AESs. The HESS consists of two elements: a battery for high energy density storage and a superconducting magnetic energy storage (SMES) for high power density storage. A dynamic droop control is used to control charge/discharge prioritization. Maneuvering and pulse loads are the main sources of the sudden changes in AESs. There are several types of pulse loads, including electric weapons. These types of loads need large amounts of energy and high electrical power, which makes the HESS a promising power source. Using Simulink/MATLAB, we built a model of the AES power grid integrated with an SMES/battery to show its effectiveness in improving the quality of the power grid.

Locating Hybrid Power Flow Controller in a 30-Bus System Using Chaotic Evolutionary Algorithm to Improve Power System Stability

Locating Hybrid Power Flow Controller in a 30-Bus System Using Chaotic Evolutionary Algorithm to Improve Power System Stability

Improvement of Power System Stability using BBO Algorithm

Improvement of Power System Stability using BBO Algorithm

Promoting acceptance of direct load control programs in the United States: Financial incentive versus control option

Residential direct load control (DLC) is an important type of demand response designed to reduce electricity consumption during peak hours through utility companies' control over the operation of certain household appliances. Despite many benefits of DLC, customers' concern for losing control has been hindering its adoption. This study aims to investigate U.S. residents' willingness to accept two popular A/C-related DLC programs in summertime with or without financial incentives or an override option, and to identify the socio-demographic characteristics associated with the decisions. Results of an online survey among 1482 U.S. residents indicate half of the participants are willing to accept DLC without any conditions; however, both an incentive of $30 and an override option boost acceptance rates. Importantly, the override option is more effective than the financial incentive. Residents who are younger, Democrats, non-Whites, have higher education levels, live in larger dwellings, and live with more people are more likely to adopt DLC than their counterparts. Residents who are older, Republicans, Whites, homeowners, and live in a house preferred an override option to financial incentives more often. The implications were discussed in terms of improving power system stability through better DLC program design and implementation.

Stability Improvement of a Multimachine Power System Connected With a Large-Scale Hybrid Wind-Photovoltaic Farm Using a Supercapacitor

This paper presents the stability improvement of a multimachine power system connected with a large-scale hybrid wind-photovoltaic (PV) farm using an energy-storage unit based on supercapacitor (SC). The operating characteristics of the hybrid wind-PV farm are simulated by an equivalent aggregated 300-MW wind-turbine generator (WTG) based on permanent-magnet synchronous generator and an equivalent aggregated 75-MW PV array. The WTG and the PV array are connected to a common dc link through a voltage-source converter and a dc/dc boost converter, respectively. The power of the common dc link is transferred to the multimachine power system through a voltage-source inverter, step-up transformers, and a connection line. The SC-based energy-storage unit, which is integrated into the common dc link through a bidirectional dc/dc converter, is employed for smoothing out the power fluctuations due to variations of wind speed and/or solar irradiance. A proportional-integral-derivative (PID)-supplementary damping controller (PID-SDC) is designed for the bidirectional dc/dc converter of the SC to enhance the damping characteristics of the low-frequency oscillations associated with the studied multimachine power system. The root loci of the studied system are examined under wide ranges of wind speed and solar irradiance. The effectiveness of the proposed SC joined with the PID-SDC on improving the performance of the studied system under different disturbance conditions is also demonstrated using time-domain simulations.

Virtual synchronous generator model based control of PV for power system stability improvement in a large-scale power system with a massive integration of PVs

In this paper, virtual synchronous generator (VSG) model based control of photovoltaic power generations (PVs) for power system stability improvement is proposed. Different from other studies on VS...

Stability of DC Power networks with Constant Power Loads for Small Sized Applications

This paper studies the stability characteristics of small sized dc power networks with constant power loads being connected to the network. With the increased application of dc distributed power systems and active loads, maintaining stability in dc power networks with high usage of constant power load has become an important issue. Motivated by the fact that small sized dc systems would have difficulties with accommodating stability improvement methods that require installation of additional components, this paper performs stability analysis and explores application of virtual resistance based approaches for stability improvement in dc power systems. The performance of the studied control approaches is also verified and the characteristics of the considered approaches are also studied.

Tuning of power system stabilizer for small signal stability improvement of interconnected power system

This paper reports a new technique for achieving optimized design for power system stabilizers. In any large scale interconnected systems, disturbances of small magnitudes are very common and low frequency oscillations pose a major problem. Hence small signal stability analysis is very important for analyzing system stability and performance. Power System Stabilizers (PSS) are used in these large interconnected systems for damping out low-frequency oscillations by providing auxiliary control signals to the generator excitation input. In this paper, collective decision optimization (CDO) algorithm, a meta-heuristic approach based on the decision making approach of human beings, has been applied for the optimal design of PSS. PSS parameters are tuned for the objective function, involving eigenvalues and damping ratios of the lightly damped electromechanical modes over a wide range of operating conditions. Also, optimal locations for PSS placement have been derived. Comparative study of the results obtained using CDO with those of grey wolf optimizer (GWO), differential Evolution (DE), Whale Optimization Algorithm (WOA) and crow search algorithm (CSA) methods, established the robustness of the algorithm in designing PSS under different operating conditions.

Frequency stability improvement of micro hydro power system using hybrid SMES and CES based on Cuckoo search algorithm

Micro hydro has been chosen because it has advantages both economically, technically and as well as in terms of environmental friendliness. Micro hydro is suitable to be used in areas that difficult to be reached by the grid. Problems that often occur in the micro hydro system are not the constant rotation of the generator that caused by a change in load demand of the consumer. Thus causing frequency fluctuations in the system that can lead to damage both in the plant and in terms of consumer electrical appliances. The appropriate control technology should be taken to support the optimum performance of micro hydro. Therefore, this study will discuss a strategy of load frequency control by using Energy Storage. Superconducting magnetic energy storage (SMES) and capacitor energy storage (CES) are devices that can store energy in the form of a fast magnetic field in the superconducting coil. For the optimum performance, it is necessary to get the optimum tuning of SMES and CES parameters. The artificial intelligence methods, Cuckoo Search Algorithm (CSA) are used to obtain the optimum parameters in the micro hydro system. The simulation results show that the application of the CSA that use to tune the parameters of hybrid SMES-CES-PID can reduce overshoot oscillation of frequency response in micro hydro power plant.

Transient Stability Improvement of Power System Integrated with Wind Generation

Transient Stability Improvement of Power System Integrated with Wind Generation

Improving power system stability in the presence of wind farms using STATCOM and predictive control strategy

In this study, a multi-objective predictive control strategy is presented for the stability improvement of a power system in the presence of wind farms and STATCOM. The main contribution of this study is in the multi-objective consideration for controlling the active and reactive powers of the rotor-side converter in each of the induction generators, controlling the voltage of the synchronous generators’ excitation system, and designing the damping controller of STATCOM using the predictive strategy. To reduce the computational burden, and to accurately choose the input paths into the predictive control, the Laguerre functions are used. Also, for reducing the sampling time in the selection of large prediction horizons, the exponential data weighting has been employed. The simulation results were evaluated using MATLAB software in the field of time and frequency under different scenarios. Moreover, the obtained results of each domain are compared using the two techniques of the predictive strategy, i.e. the classic model, Laguerre functions, and also the conventional proportional integral controller. The comparison of these three methods reveals that the functional predictive control outfits the two other controllers in damping of the oscillations.

Stability improvement of power systems connected with developed wind farms using SSSC controller

Abstract This paper studies the performance of SCIG wind farm, DFIG wind farm, and a combined wind farm (CWF) during three-phase grid fault. The SCIG and DFIG wind farms are equipped with Static Synchronous Series Compensator (SSSC) whereas the combined wind farm did not have one. Since the CWF is composed of an equal number of Double Feed Induction Generators (DFIGs) and Squirrel Cage Induction Generators (SCIGs), it incorporated the main advantages of both types of generator. More specifically, the SCIG has a lower cost, but its drawback lies in its negative impact on system stability, especially when it operates without a shunt compensator. On the other hand, the DFIG, though more expensive, is better able to maintain the stability of the system. The SCIG and DFIG wind farms are equipped with SSSC controller to control the active and reactive line power flow. The results of a comparative study of DFIG and SCIG wind farms with SSSC and combined wind farm without SSSC during a three-phase grid fault showed that even though the SSSC improved the performance of the DFIG and SCIG wind farms, the CWF without the SSSC controller is found to have the best performance. The stability of the three wind farms is examined using Voltage Stability Index (VSI). All of the test scenarios are simulated with MATLAB.

Improving Power System Stability Using Transfer Function: A Comparative Analysis

In this paper, a small-signal dynamic model of a single-machine infinite-bus (SMIB) power system that includes IEEE type-ST1 excitation system and PSS based on transfer function structure is presented. The changes in the operating condition of a power system on dynamic performance have been examined. The dynamic performance of the closed-loop system is analyzed base on its eigenvalues. The effectiveness of the parameters changes on dynamic stability is verified by simulation results. Three types of PSS have been considered for analysis: (a) the derivative PSS, (b) the lead-lag PSS or conventional PSS, and (c) the proportional-integral-derivative PSS. The objective function is formulated to increase the damping ratio of the electromechanical mode eigenvalues. Simulation results show that the PID-PSS performs better for less overshoot and less settling time compared with the CPSS and DPSS under different load operation and the significant system parameter variation conditions.

Improving Power System Stability Using Transfer Function: A Comparative Analysis

Improving Power System Stability Using Transfer Function: A Comparative Analysis

A Study on Protection Requirements for DC Faults in Multi-Terminal HVDC System

Recently, the construction of large-scale offshore wind farms and dissemination of new and renewable energy has encouraged a growing interest in DC systems. In particular, HVDC (high-voltage direct current) systems have been evaluated as the best alternative because of their power system interconnection and large-scale power transmission. Because HVDC systems offer many advantages such as a low insulation level, transmission losses, and improved power system stability, many studies on DC power systems are actively underway. As compared to the point-to-point HVDC system, which connects the electricity generated from geographically scattered renewable energy sources to an existing AC power system on a 1:1 basis, the MTDC (multi-terminal HVDC) system has garnered greater attention because of its ability to control energy flow by connecting several HVDC outputs to the HVDC. Because the VSC-HVDC, which operates as an MTDC, supplies not only active power, but also reactive power, it has been deemed the optimal solution to connect a renewable energy source to a system with no existing AC power supply, such as a wind-power generation system. An MTDC system, which possesses a structure that is more complex than that of the point-to-point HVDC system, should be equipped with a high-speed DC circuit breaker that can quickly separate a conversion station from the DC transmission line to which it is connected in the event of a fault or malfunction at the station. In addition, DC protection on the MTDC grid must be reliable and operate much faster than conventional AC protection to ensure that the converter sends a trip signal before it is damaged. In this paper, we propose a protection scheme for the DC line to effectively activate the DC circuit breaker, which is essential in an MTDC system; additionally, system modeling and simulation using the PSCAD/EMTDC were performed to verify the proposed algorithm.

Necessary Condition to Utilize Adaptive Control in Wind Turbine Systems to Improve Power System Stability

Necessary Condition to Utilize Adaptive Control in Wind Turbine Systems to Improve Power System Stability

Comparison of secondary arcs for reclosing applications

This paper presents a comparison of secondary electric arcs behavior for reclosing applications. The main objective of the paper is to show the differences in secondary arcs during simulations, laboratory tests and real life events. These comparisons can help engineers develop adaptive reclosing algorithms and improve power system stability. A software arc model, a laboratory test result and field events' harmonic contents were analyzed. Although the harmonics may differ in each method, they all provide enough information to be used in the reclosing algorithms.

Application of UIPC to improve power system stability and LVRT capability of SCIG‐based wind farms

This study discusses the possibility of the connection of squirrel cage induction generator (SCIG)-based wind farms (WFs) to power system through unified inter-phase power controller (UIPC) to improve the low-voltage ride-through (LVRT) capability of WF and enhance the power system stability. The UIPC is based on inter-phase power controller (IPC), where its phase-shifting transforms (PSTs) are replaced by two series converters (SECs) and one shunt converter (SHC). The operation of the UIPC is divided into normal and LVRT operation modes. In normal operation mode, the UIPC injects the total active power generated by the WF to power system and controls the power factor of the UIPC connecting point (CP) by reactive power control. In LVRT mode, the WF which is connected through UIPC, acts as a flexible AC transmission system device with capability of active and reactive power controls at CP. In this study, the UIPC model is developed based on phase angles of injected SECs voltage and a unified control scheme including UIPC SECs, UIPC SHC and pitch angle control of wind turbine, is proposed to improve LVRT capability of WF and power system stability during faults. Also, the impact of the simultaneous application of the IPC and static synchronous compensator is studied and compared with the application of the UIPC for connecting the SCIG-based WFs to the power system. The PSCAD/EMTDC simulation results show that the UIPC presents an effective solution for connecting WFs to power system.

Transient and Dynamic Stability Improvement of a Single Machine Infinite Bus Power System using Adaptive Fractional Order Proportional Integral Derivative Power System Stabilizer

Abstract: This paper presents a study of the transient and dynamic stability enhancement and control of a synchronous generator connected to an infinite bus (single machine infinite bus system) via two parallel transmission lines when the power system working under different operating conditions and subjected to different disturbances. An effective mean of damping the oscillations resulting from these disturbances is to provide the synchronous generator with power system stabilizer. An adaptive fractional order proportional integral derivative controller is suggested to play the role of power system stabilizer in this paper. The results obtained from simulation study are presented and discussed.