Voltage Stability Of Power Grid Research Articles

Real-Time Monitoring Method of Power Grid Voltage Stability During Geomagnetic Storms

Real-Time Monitoring Method of Power Grid Voltage Stability During Geomagnetic Storms

CNN‐LSTM based power grid voltage stability emergency control coordination strategy

AbstractThe occurrence of cascading failure and small probability contingency in hybrid AC/DC power grid aggravates the mismatch risk of traditional emergency control with offline‐predetermination–online‐practice (ODOP) mode. To ensure the voltage stability of power grid under large disturbances, this paper proposes a voltage stability emergency control coordination strategy based on convolutional neural network (CNN) and long short‐term memory (LSTM) network. First, the mismatch mechanism of traditional emergency control is revealed under the variation of operating conditions. Second, the start criterion of complementary emergency control with ODOP mode is proposed, and the CNN‐LSTM network is established to quantitatively evaluate the voltage stability margin. Finally, the emergency control sensitivity index is proposed to predict the stability margin enhancement under alternative emergency control measures, and the optimal ODOP‐based emergency control strategy is determined to coordinate multiple voltage stability emergency control measures. Case studies are performed in the actual Northwest China local region hybrid AC/DC power grid with voltage instability problems, and the simulation results verify the effectiveness of the proposed method.

Analysis of VSC-HVDC support capability for power grids with large-scale renewable energy and multi-infeed HVDC links

Henan Power Grid is located in the north of Central China Power Grid. During its energy transition, thermal power units will be decommissioned on a large scale. Therefore, the scale of the new energy grid connection and regional external power will be further greatly increased to match the load growth demand. Under this background, Henan Power Grid plans to introduce the third HVDC (High Voltage Direct Current). Based on the actual data and the current operation status of Henan Power Grid, this paper proposes an analysis strategy about VSC-HVDC (Voltage Source Converter HVDC) to improve the support capability of the receiving power grid with multi-infeed HVDC. In recent years, VSC-HVDC technology has emerged with the strengths of flexible power regulation and strong voltage support. This paper firstly analyzes the VSC-HVDC power transmission characteristics and clarifies the mechanism of the VSC-HVDC power regulation. Then, based on the actual planning of Henan power grid, the influence of two feed-in schemes (LCC-HVDC (Line Commutated Converter HVDC) and VSC-HVDC) on the voltage stability of power grid and the number of subsequent commutation failures of other conventional DC are compared and analyzed under the three-phase short-circuit fault of AC lines near HVDC terminal location by using PSD-BPA simulation software. The results show that the VSC-HVDC scheme can effectively alleviate the voltage fluctuation (duration within 1 s and fluctuation number within 2 times) after the fault and restrain the number of subsequent commutation failures of conventional DC(with 2 times and even none).

Distributed multi-energy storage cooperative optimization control method for power grid voltage stability enhancement

To solve the problem of grid voltage fluctuation in multi-energy systems, this study proposes a voltage optimization control method based on the coordination of battery storage, heat storage, and gas storage. First, the different operation modes of electricity, heat, and gas in the system were analysed, and a coupling model of an energy system with multi-energy storage was established. Second, according to the energy storage characteristics of distributed energy storage, a collaborative optimization model of distributed energy storage was established by studying the influence mechanism of battery storage, gas storage, and heat storage on grid voltage stability. Taking the minimum voltage fluctuation as the optimization objective, a coordinated operation strategy of distributed energy storage is proposed under the premise of meeting the constraints of distributed energy storage. Combined with the real-time charging and discharging states of each distributed energy storage system, the particle swarm optimization method was used to maintain the node voltage stability. Finally, a regional multi-energy system is taken as an example to verify that the proposed collaborative optimization control method can effectively improve grid voltage stability. Through the results, it can be seen that the node voltage in the regional power grid has increased by 0.012p.u., 0.012p.u. 0.011p.u. 0.014p.u.

Impact Analysis of Distributed Solar Photovoltaic Power Generation System Integration on Power Grid Voltage Stability Using Static Techniques

Recently, the rise in consumption of electrical energy and power transmission between various utilities has resulted in the emergence of anxieties about the power system's network voltage stability. Additionally, the necessity for power systems to perform in a secure condition has increased due to an increase in load demand globally. Therefore, the use of renewable energy-based distributed generation is growing quickly to help meet electrical demand and disrupt environmental issues caused by the use of fossil fuels. This type of generation can have a positive or negative influence on the stability of the power system. This paper analyzes the effects of distributed PV power integration on the power grid's voltage stability using static techniques. In order to improve efficacy and accuracy, give a complete and in-depth understanding of the problem of voltage stability, and identify the causes of instability, a combination of four different techniques is employed for analysis. Analysis methodologies include modal analysis, sensitivity analysis, PV curve, and QV curve. The analysis of voltage stability is carried out on an IEEE 14-bus system by using NEPLAN software. The simulation results showed that the integration of a renewable energy resource-based distributed solar PV power system into the test system led to a noticeable improvement in stability degree, a decrease in sensitivity of buses, a significant improvement in system MW loading, an enhancement in voltage profile, and a perceptible increase in reactive power margin

Siting and sizing of synchronous compensator based on electromagnetic transient simulation

With the increasing load of power grid and the access of new energy sources and direct current lines, power grid voltage stability becomes increasingly prominent. Installing synchronous compensator is an option to supplement reactive power and improve voltage stability. Compared with other reactive power compensation equipment (SVC, SVG, etc.), synchronous compensators have advantages in service life, size, easy to maintenance and etc. Siting and sizing of synchronous compensator are critical for investment and voltage stability adjustment performance of the equipment. Considering that the power grid contains new energy and HVDC equipment, it is necessary to use electromagnetic transient (EMT) simulation to evaluate transient stability of a power system when the siting and sizing of a synchronous compensator was determined. In this paper, a method of siting and sizing the synchronous compensator based on voltage sensitivity index (VSI), severity index (SI) and EMT simulation is proposed. VSI of different bus in the system is calculated by injecting reactive power into each bus, and the suitable candidate bus location for compensator is obtained. Furthermore, the calculation of power grid fault severity index is designed, and the synchronous compensator sizing method with the SI as optimization objective is designed. An actual AC–DC hybrid power grid system with 1343 buses was used to test the proposed methods and testing results demonstrate the performance of the proposed method.

A framework to assess voltage stability of power grids with high penetration of solar PV systems

In recent years, grid integration of solar photovoltaic (PV) systems has proliferated across many countries in order to reduce greenhouse gas emission and minimize energy cost. However, the intermittency inherent within PV generator may affect the grid voltage stability significantly. Therefore, it is imperative to consider the intermittent nature of solar PV power generation and uncertainties associated with load demand to gain a clear insight on power grid voltage stability with high PV penetration. In this Writing – original draft, a framework is presented for power grid voltage stability analysis considering uncertainties of PV power generation and load demand using Monte Carlo simulation. The expected values of voltage stability indices such as critical eigenvalue, line loss, reactive power margin and loading margin have been determined in the proposed framework and their probability distribution have been obtained for different times throughout a day. The proposed methodology has been verified by analysing voltage stability of the modified IEEE 14 bus test system with high penetration of PV energy sources and considering uncertainties associated with load demand. The results provide a holistic understanding on voltage stability of the test system with different penetration levels of PV energy sources into the power grid during contingency as well as normal operating conditions.

Study on the Impact of Renewable Energy Power Generation Transient Characteristics on System Stability in Weak Grid

With the large-mount access of renewable energy to the electric power grid, the unique seasonal and day and night output fluctuation of renewable energy power generation has brought new challenges to the stable and safe operation of the power system. These challenges mainly include the impact on power grid voltage stability, frequency stability and power angle stability. Therefore, the impact of renewable energy power generation on the stable and safe operation of power system should be be paid enough attention. Due to the characteristics of long-distance, large-scale and high concentration of grid connected renewable energy, the ability of AC system to connect to power grid is relatively weak, which is a typical weak current network. With the continuous expansion of renewable energy grid connection scale, the dynamic characteristics of weak current power grid become more complex, which brings great challenges to the stability and security of power grid. However, in the calculation of power system security and stability, more conservative renewable energy generation model parameters are often used to fix the power grid operation reliability. For better improve the renewable energy acceptance capacity of the system, the proportion of renewable power generation will be further increased. Therefore, establishing an accurate and reasonable renewable energy model is the basis of large-scale renewable energy grid connection security and stability calculation. Further study on the control strategy and parameter adaptability of renewable energy model could be reduced stability risk of high proportion of renewable energy connected to weak current network.

Distributed Multi-Energy Storage Cooperative Optimization Control Method for Power Grid Voltage Stability Enhancement

Distributed Multi-Energy Storage Cooperative Optimization Control Method for Power Grid Voltage Stability Enhancement

Research on voltage stability and control strategy of power system considering grid connected charging of electric vehicles

The development of new energy vehicles is an important measure to deal with the growing energy demand and climate change. Especially in recent years, with the support of national policies and the maturity of electric vehicles(EVs) related technologies, the number of EVs has increased explosively, and the situation is very good. However, it also means that a large number of charging loads will be connected to the power grid, which will put great pressure on the safe and stable operation of the power grid. Although there have been many studies on the impact of EVs integration into modern power grid, most of the EVs load models are based on probability function and lack accuracy. Therefore, starting with the actual operation data of EVs charging station, this paper studies the influence of a large number of EVs charging loads on the static voltage stability of power grid. It is found that the charging load of large-scale EVs is added to the power grid, which significantly reduces the stability of power grid voltage, especially at the place connected to the EVs load and far away from the balance node. In addition, when the charging station adopts the time-of-use(TOU) price strategy, it can effectively improve the voltage stability of the whole network.

Using enhanced crow search algorithm optimization-extreme learning machine model to forecast short-term wind power

The strong volatility and randomness of wind power impact the grid and reduce the voltage quality of the grid when wind power is connected to the grid in large scale. The power sector takes the wind abandonment measures to ensure the grid voltage stability. The enhanced crow search algorithm optimization-extreme learning machine (ENCSA-ELM) model is proposed to accurately forecast short-term wind power to improve the utilization efficiency of clean energy. (1) The enhanced crow search algorithm (ENCSA) is proposed and applied to short-term wind power forecast. The convergence performance test revealed that the local development and global exploration capabilities of the ENCSA were enhanced, and the test result of the proposed ENCSA algorithm outperformed other well-known nature inspired algorithms and state-of-the-art CSA variants; (2) The output and input of the forecasting models were determined by analysis of the wind power impact factors and the wind power samples in autumn, winter and spring were forecasted by the ENCSA-ELM model; and (3) The forecast results were analyzed by multiple evaluation indexes. The simulation experiments revealed that the error interval and evaluation indexes of the ENCSA-ELM model outperformed the state-of-the-art wind power forecast methods, traditional machine learning models and ELM optimized by other algorithms. The RMSE value and MAPE value of the proposed model were controlled below 20% and 4%. Accurate wind power prediction maintains the voltage stability of power grid and increases the utilization efficiency of clean energy.

Two-stage ADMM-based distributed optimal reactive power control method for wind farms considering wake effects

Since the connection of small-scale wind farms to distribution networks, power grid voltage stability has been reduced with increasing wind penetration in recent years, owing to the variable reactive power consumption of wind generators. In this study, a two-stage reactive power optimization method based on the alternating direction method of multipliers (ADMM) algorithm is proposed for achieving optimal reactive power dispatch in wind farm-integrated distribution systems. Unlike existing optimal reactive power control methods, the proposed method enables distributed reactive power flow optimization with a two-stage optimization structure. Furthermore, under the partition concept, the consensus protocol is not needed to solve the optimization problems. In this method, the influence of the wake effect of each wind turbine is also considered in the control design. Simulation results for a mid-voltage distribution system based on MATLAB verified the effectiveness of the proposed method.

Analysis of Power Grid Voltage Stability With High Penetration of Solar PV Systems

Grid integration of solar photovoltaic (PV) systems has been escalating in recent years, with two main motivations: reducing greenhouse gas (GHG) emission and minimizing energy cost. However, the intermittent nature of solar PV generated power can significantly affect the grid voltage stability. Therefore, intermittent solar PV power generation and uncertainties associated with load demand are required to be accounted for to gain a holistic understanding on power grid voltage stability with the high penetration of PV energy sources. This article presents a framework for power grid voltage stability analysis considering uncertainties associated with PV power generation and load demand using Monte Carlo simulation. Commonly used voltage stability indicators such as critical eigenvalue, line loss, reactive power margin have been considered in the proposed framework. The proposed methodology has been verified by analyzing the voltage stability of the IEEE 14 bus test system, with the high penetration of PV energy sources and considering uncertainties associated with load demand. The results provide a clear insight into the voltage stability of power grid with different penetration levels of PV energy sources into the power grid.

Summary on Voltage Stability of Power Grid in Large-scale Wind Power Area

With the rapid development of wind power, the voltage stability of large-scale wind farms is becoming increasingly important. In this paper, voltage stability are classified: the static voltage stability and the transient voltage stability .In this paper, a lots of voltage stability problems were analyzed and explored. For example, the voltage of chaos, bifurcation, the low voltage ride through and the high voltage ride through We should research fault prediction, fault diagnosis and a fan to take off the net after corresponding strategy.

Coordinated reactive power optimization for multi-TSO grids in an autonomous way

Purpose It is very indispensable for the various control centers of multi-transmission system owners (TSOs) grids to coordinate their reactive power optimization (RPO) efforts. However, such coordinated equilibrium point is comparatively hard to achieve unless one TSO control center could obtain all grids’ information in detail, which may lead to confidential issue and heavy communicating load. The purpose of this paper is to propose a solution to optimizing the reactive power control efforts among multi-TSOs grids with a mathematic interconnection model and reasonable communication cost. Design/methodology/approach Based on the interconnected power network equation, the stability-related optimum reactive power injection and the power-loss-related optimum reactive power injection were derived, respectively. Furthermore, according to the decomposition-and-coordination-based computing methodology, a coordinated RPO model for interconnected TSOs was designed, taking into consideration both the static voltage stability and economy. Findings The extreme values for the indicator L of power grid voltage stability and active power loss function were found and proved to be minimums. According to these extreme values, an expression for the reactive power injection at interconnected nodes between TSOs grids was obtained, and a coordinated strategy of RPO was established, which could take the static voltage stability and economy into consideration without confidential concern. Originality/value The existence of minimum values for indicator L of voltage stability and power loss was demonstrated, respectively. And the method presented in this paper can ensure the safety of information among different TSO grids, i.e. avoiding confidential issues. In particular, the coordinated control method can be implemented on the local power grid without knowing all of the parameters of its interconnection.

Voltage Stability of Power Grids with PV Plants using Robust LPV-Control

Abstract: This paper proposes a new approach to control PV plants using linear parameter varying systems (LPVS) to overcome limitations of controllers designed based on single linearizations. The nonlinear PV plant is transformed into an LPVS and a feedback LPV controller is obtained, which is robust against bounded variations in the input matrix. Finally, the LPV controller is compared with a reference controller, and it is shown for an example that the proposed controller outperforms the reference controller by achieving voltage stability.

A Method of Data Integration Check Based on Online Operation Data of Large-Scale Power System

An important part of power grid voltage stability online intelligent warning system was to research into the current Energy Management System real-time power grid operation parameters and power networks offline data splicing integration, form a set of online dynamic simulation trend data, and implement preventive voltage stability calculation. A splicing model of power grid online data integration and practice was established, and a grid online data splicing method was proposed, which had been verified by actual data. The method of practical data online and offline networks data integration can significantly improve the accuracy of the simulation data.

The Role of the Offline/Online Data Mapping Table Based on Online Operation Data of Large-Scale Power System

An important part of the Xinyang power grid voltage stability online intelligent warning system was to research into the current system of EMS real-time power grid operation parameters and power networks offline data splicing integration, forming a set of online PSASP (Power System Analysis Software Package) trend data, implementing preventive voltage stability calculation. By splicing model of Xinyang grid online data integration and practice, summed up the grid online data splicing method and the model, this article mainly introduced the offline and online data mapping change reason, function is established. It had been verified by actual data achieved by the method can significantly improve the accuracy of the data. It was a kind of practical data online and offline networks data integration method.

Modeling of Variable-Speed Wind Generator and Study of Voltage Stability of Power Grid with High Wind Power Penetration

In this paper, the variable speed wind turbine model based on doubly-fed induction generator (DFIG) and a practical power grid model to be studied are implemented in DIgSILENT / PowerFactory. The transient voltage stability and the static voltage stability of the power grid with high wind power penetration will be studied.

Influence of AC System Strength on Voltage Stability of DC Receiving-End Power Grid

The AC system strength at DC receiving-end exerts great influences on the voltage stability of power grid. The selected DC control modes and reactive power compensation mode should fit with the AC system strength at receiving end. This paper analyzes the influences of AC system strength at DC receiving-end on voltage stability of power grid from the point of mechanism, and conducts simulations based on Shandong power grid.