Power Stability Control Research Articles

Improving cyber-physical-power system stability through hardware-in-loop co-simulation platform for real-time cyber attack analysis

With advancements in communication systems and measurement technologies, smart grids have become more observable and controllable, evolving into cyber-physical-power systems (CPPS). The impact of network security and secondary equipment on power system stability has become more evident. To support the existing grid toward a smart grid scenario, smart metering plays a vital role at the customer end side. Cyber-Physical systems are vulnerable to cyber-attacks and various techniques have been evolved to detect a cyber attack in the smart grid. Weighted trust-based models are suggested as one of the most effective security mechanisms. A hardware-in-loop CPPS co-simulation platform is established to facilitate the theoretical study of CPPS and the formulation of grid operation strategies. This paper examines current co-simulation platform schemes and highlights the necessity for a real-time hard-ware-in-the-loop platform to accurately simulate cyber-attack processes. This consideration takes into account the fundamental differences in modeling between power and communication systems. The architecture of the co-simulation platform based on RT-LAB and OPNET is described, including detailed modeling of the power system, communication system, and security and stability control devices. Additionally, an analysis of the latency of the co-simulation is provided. The paper focuses on modeling and implementing methods for addressing DDOS attacks and man-in-the-middle at-tacks in the communication network. The results from simulating a 7-bus system show the effectiveness and rationality of the co-simulation platform that has been designed.

Optimized robust control for improving frequency response of delay dependent AC microgrid with uncertainties

Converter-interface-based renewable energy incorporated into modern power systems causes deterioration in power system stability and it is proving to be a main challenge for operators using sluggish traditional generation with a growing share of converter-interface generation, and there is a need for an alternative means to deliver rapid frequency control. This paper proposes two control loops as secondary frequency control, first is an improved optimized delay-dependent frequency control to ensure robust frequency control under daily changes in system parameters that may occur in prospective, renewable-rich future AC microgrids. For a variety of operating conditions, the design process employs a mixed H2/H∞ robust control based on linear matrix inequality (LMI). In second, a speedy-acting improved power stability control loop is utilized as the proposed secondary frequency control, because demand response aggregators can be beneficial for frequency control. Robustness is evaluated against several perturbations and communication delay attacks through dynamic simulation and stability is evaluated by small-signal analysis. Different case studies subject to generation\\load loss, multiple time delay and parameter uncertainties are demonstrated on an interconnected AC microgrid system to verify the performance of the proposed control technique.

Power stability control of wind-PV-battery AC microgrid based on two-parameters fuzzy VSG

Virtual synchronous generator (VSG) control addresses the issue of decreasing microgrid standby inertia caused by the rise in wind turbines and photovoltaic (PV) penetration. However, various types of perturbations occur frequently making the traditional constant parameter VSG control unable to meet the system performance requirements, and thus a two-parameters fuzzy VSG control is proposed to ensure that microgrid inertia and damping. Firstly, the device-level control of each generation unit in the microgrid is designed based on the wind-PV-battery alternating current (AC) microgrid architecture. Secondly, fuzzy VSG control uses fuzzy rules written in plain language to represent the relationship between the main VSG factors and the power and frequency. Then, the influence of virtual inertia and damping coefficient on the dynamic performance of the system is analyzed through the theory of small-signal model, and a reasonable variation range of VSG parameters are given. Finally, the simulation model of wind-PV-battery AC microgrid is built in MATLAB/Simulink, and compared with other improved VSG control strategies, the fuzzy VSG control proposed in this paper has better dynamic performance and safety stability. This research emphasizes the practicality and importance of utilizing fuzzy control to adjust VSG techniques for developing microgrid configurations incorporating more renewable energy sources to guarantee the reliability and efficiency of microgrid.

An intelligent analysis method of security and stability control strategy based on the knowledge graph

The security and stability control system is the guarantee of the security and stability operation of the power grid. With the increasing scale of distributed new energy access to the power grid, the security and stability control strategy of the power grid is becoming more complex, and it is becoming increasingly important to correctly analyze and implement the security and stability control strategy. In order to ensure the correctness of the security and stability control strategy implemented by the security and stability control device, it is necessary to analyze the security and stability control strategy in detail. Therefore, this article proposes an intelligent analysis method of the security and stability control strategy based on the knowledge graph. First, this article introduces the ontology design method of the security and stability control strategy based on the knowledge graph, combines the characteristics and applications of the knowledge graph, analyzes the relationship between the elements of the strategy, and designs a clear-structured knowledge network. Second, this article analyzes the automatic construction technology of the graph, constructs the six-element ontology model of the security and stability control strategy, and realizes the human–computer interaction functions such as auxiliary decision making, strategy reasoning, and intelligent search based on the knowledge graph. Using artificial intelligence technology, this article takes the security and stability control strategy of a certain area’s security and stability control system as an example to model and manage. The results show that it can assist the tester to quickly retrieve the strategy, effectively improve the detection efficiency of the security and stability control strategy, avoid the omission and ambiguity caused by the manual understanding of the strategy, and ensure the accuracy and comprehensiveness of the security and stability control strategy detection.

Reliability Assessment Method for Power Grid Security and Stability Control Devices Based on Weibull Fault Rate Fitting

Reliability Assessment Method for Power Grid Security and Stability Control Devices Based on Weibull Fault Rate Fitting

PF-FEDG: An open-source data generator for frequency disturbance event detection with deep-learning reference classifiers

Accurate and fast classification of FDEs is crucial to power systems situation awareness and stability control. However, various database used in recent studies makes it hard to directly compare different classification methods. To relieve the lack of a standardized database that can be used as a benchmark, this work proposes an open-source package which generates frequency events based on PowerFactory named PF-FEDG. PF-FEDG can produce various labeled FDEs with random parameters such as generator trips, load disconnections, line outages, frequency ramp ups, frequency ramp downs, and frequency oscillations. Furthermore, the package includes three reference FDEs classifiers based on deep learning techniques. These models are tested on the IEEE 39-bus system and IEEE 118-bus system and achieve high performance. The package generating capability and the reference classifiers can be used by the community as benchmarks for comparison and development of new algorithms for FDEs detection. The code of PF-FEDG is available on GitLab.

Analysis and Suppression of Laser Intensity Fluctuation in a Dual-Beam Optical Levitation System.

Levitated micro-resonators in vacuums have attracted widespread attention due to their application potential in precision force sensing, acceleration sensing, mass measurement and gravitational wave sensing. The optically levitated microsphere in a counter-propagating dual-beam optical trap has been of particular interest because of its large measurement range and flexible manipulation. In this system, laser intensity fluctuation directly influences the trap stability and measurement sensitivity, which makes it a crucial factor in improving trapping performance. In this paper, a time-varying optical force (TVOF) model is established to characterize the influence of laser intensity fluctuation in a dual-beam optical trap. The model describes the relationship between the laser intensity fluctuation, optical force and the dynamic motion of the micro-sized sphere. In addition, an external laser intensity control method is proposed, which achieved a 16.9 dB laser power stability control at the relaxation oscillation frequency. The long-term laser intensity fluctuation was suppressed from 3% to 0.4% in a one-hour period. Experiments showed that the particle’s position detection sensitivity and the stability of the relaxation oscillation could be improved by laser intensity fluctuation suppression.

A blockchain-based lightweight identity authentication scheme for the IEDs of security and stability control system

As an important part of the second defense line of the power system, the Security and Stability Control System (SSCS) is of great significance to ensure the reliable operation of the power system. However, SSCS still lacks an effective security mechanism and is easily accessed by attackers, thus posing a threat to the stable and reliable operation of the power system. To tackle this issue, we propose a blockchain-based identity authentication scheme for Intelligent Electronic Devices (IEDs) of SSCS. We first propose an identity authentication system model for IEDs and design the deployment of consortium chain nodes on IEDs, with architectural characteristics of SSCS and the working scenario of IEDs taken into consideration. The consortium chain is used to store credentials required for authentication, ensuring that they are tamper-proof. We combine IP address, port number and physical ID, and propose the unique identification of IEDs, with a data structure designed for the identification. We also propose a lightweight identity authentication method based on renewable hash chains, with hash chains used as one-time authentication passwords, and introduce a renewal mechanism of hash chains. Further, the detailed processes of registration and authentication phase are designed. Finally, the security analysis shows that our identity authentication scheme can resist various attacks, and the feasibility of our scheme is verified by experiments.

Power Stability and Frequency Control Techniques of DG for a High Penetration Wind-Based Energy Storage System Using Integral–Derivative Controller

Distributed generation (DG) has environmental as well as economic benefits and develops new concepts to make the power network more effective and minimize pollution in the environment. Being the fluctuation behavior of renewable energy sources (RESs), generation, balance, and demand is not an easy task to control because it is not desirable to have a constant power generation from RESs due to natural prospects. As a result, the dynamic stability of power flow and control of frequency is becoming more challenging due to the high penetration impacts of RESs. In this article, we have proposed a control algorithm with two scenarios for a high-penetration/hybrid diesel wind-based energy storage system to maintain the dynamic stability of power flow and control the frequency in the overall power system. The results show, using an integral–derivative (I–D) controller, the transient time of wind power flow and the fluctuation rate of frequency are reduced significantly compared to the prior research of publication. To regulate the network frequency, a storage system (battery) was used to store the excess energy without throwing it to the secondary/dump load (DL) and minimize the wastage of power produced by the wind turbine. The battery was supplied the excess wind power when there is a high load demand.

Research on output power stability control method of EV-DWPT system

Research on output power stability control method of EV-DWPT system

Multi-level model predictive control for all-electric ships with hybrid power generation

Power availability to preserve propulsion is a vital issue in the shipping industry which relies on persistent power generation and maintaining the stability of the power and propulsion system. Since the introduction of on-board all-electric Direct Current Power and Propulsion Systems (DC-PPS) with hybrid power generation, which are more efficient compared to direct-diesel and Alternating Current (AC) all-electric configurations, there have been extensive investigations on stabilization and power generation control to enable robust and reliable performance of DC-PPS during different ship operations. In this paper, a multi-level approach is proposed for hybrid power generation control. For this goal, first, a mathematical model is proposed for each power system component and then, the overall on-board power system is modeled in a state space format. Then, a multi-level Model Predictive Control (MPC) approach is proposed for the DC voltage control which unlike conventional droop control approaches, takes the DC current generated by power sources into account explicitly. The performance of the proposed approach is evaluated via several simulation experiments with a high fidelity model of a high voltage DC-PPS. The results of this paper lead to enabling more effective approaches for power generation and stability control of constant power loaded microgrids.

Research on Self-Healing Mode of Communication Channel of Regional Power Grid Stability Control System

Under the new situation of large power grids, security and stability control systems and their communication channels are facing new changes and new requirements. The article proposes a smart grid dispatching control system multi-channel information intelligent comparison method, through the network monitoring method to obtain the main plant station information interactive communication message, using the intelligent comparison algorithm to compare remote signalling, telemetry, sequence of events (SOE), Communication protocol parameters such as remote control and remote adjustment are compared, and alarm events are output in time according to the comparison results. By combining the principle of the stability control device and the principle of communication self-healing, the influence of the stability control channel communication self-healing ability on the operation of the stability control device is analysed, and the influence of whether self-healing is adopted in operation is analysed. Based on the comparison, it is concluded that the communication channel of the regional network stability control system should use self-healing method.

Design of the Servo Control System Based on EtherCAT P

EtherCAT is fully compliant with Ethernet standards, with 100Mbps transfer speed and good synchronization. It is widely used in the industrial field, such as the servo control system, robots, and numerical control machine tool. There are still lots of wires for power and communication in these applications, especially in the complex multi-axis system, leading to high installation cost and poor reliability. In this paper, a novel servo control system based on EtherCAT P is proposed. The EtherCAT P technology is an addition to EtherCAT, which can enable the standard 4-wire Ethernet cable to transmit not only data but also two electrically isolated power supplies. The hardware design and software architecture of the servo control system are described including servo motor controller, powered device, and power sourcing devices. A servo control system with one servo slave and TwinCAT master is built and some tests are carried out. The experimental results verify the power supply capacity, stability, and motor control functions.

Optimized Design of a Pump Laser System for a Spin Exchange Relaxation Free Inertial Measurement Device.

In order to improve the precision and beam quality of a pump laser for a spin exchange relaxation free inertial measurement device, we applied one scheme to achieve the square wave modulation and power stability control of the pump laser and another one to obtain the uniform intensity distribution of the laser beam, in which the acousto-optic modulator (AOM) and proportion integration differentiation (PID) controller were used to achieve the former, and the freeform surface lens was designed and optimized to achieve the latter based on the TracePro software. In experiments, the first-order diffraction light beam coming through the AOM had a spot size of about 1.1 × 0.7 mm2, and a spherical vapor cell with a radius of 7 mm was placed behind the freeform surface lens. Results show that the uniformity of the reshaped intensity distribution is higher than 90% within the target area with a radius of 7 mm both in the simulation and the experiment, which ensure that the uniform laser beam covers the area of cell. On the other hand, the power stability of the pump laser is controlled to be less than 0.05%. Compared with traditional methods, the complicated calculation process in optical design is better solved, and a higher uniformity with slight energy loss is achieved.

A remote test method for power grid security and stability control system and its engineering application

Security and stability control (SSC) system or special protection system (SPS) is an important means to ensure the safe operation of power grid. In view of the insufficiency that the current open-loop testing method cannot fully test the SSC system on-site, a remote real-time closed-loop test method is proposed. The solutions of key techniques such as information interaction, remote communication and signal conversion in remote test system are studied. Then the platform architecture and standard interface of the remote test system are designed. A remote test platform for SSC system is developed, and there application modes of the platform is deeply analysed. Finally, taking SSC system of Yunnan AC power outgoing grid as pilot application, experiment of two substations on-site is carried out. The results in practical project further prove the effectiveness of the method presented in this paper.

Power Stability Control Strategy of the WPT System Based on Load Detection

The output power fluctuates when offset occurs between the receiving coil and the transmitting coil or load equivalent impedance changes in a wireless power transfer system (WPT). These two conditions will affect the safety of the system and the life of the battery load. Therefore, effective control methods are needed to ensure the stability of the load power. This paper analyzes the WPT system with LCC/S compensation topology and the secondary side containing DC/DC circuit. The relationship between mutual inductance and load voltage and current, mutual inductance and the system transmission efficiency, DC/DC circuit duty ratio and load voltage and current are deduced. The output power stability control strategy through load voltage and load current detection and control of DC/DC circuit is proposed. Finally, the WPT system with 1 kW output power is built through simulation and experiment, which verifies the effectiveness and correctness of theoretical analysis and control strategy in this paper.

Output power stabilization control strategy of WPT systems based on secondary side circuit

In the wireless power transfer (WPT) system, the output power is sensitive to the change of mutual inductance and load resistance. It is necessary to keep the output power stable quickly through effective control methods when the receiving coil and transmitting coil are offset or the load equivalent impedance changes. Based on the analysis of the WPT system with DC/DC converter on the secondary side, the relationship between mutual inductance and load voltage and load current, as well as the relationship between duty cycle of DC/DC converter and load demand power are given. A mutual inductance identification method based on load voltage and load current detection is proposed to monitor mutual inductance changes in real time. The output power stability control strategy based on DC/DC converter is also proposed. Finally, the effectiveness and correctness of the theoretical analysis and control strategy in this paper were verified by simulation and experiment.

A High Precision Time Synchronization Method for Smart Grid based on Beidou Satellite System

With the rapid development of power grid and the large-scale application of automation equipment in power station, the requirement of high precision time synchronization for power system production and control is rapid growth. The accuracy of time synchronization for power system is an important basis to guarantee power network operation control and fault analysis, and a fundamental guarantee to improve power network accident analysis and stability control. In order to ensure that the automatic device receives accurate time synchronization signal, time monitoring and application schemes of different technical routes are studied in this paper. It is proposed that the precise monitoring based on the direct measurement of Beidou can realize high precision time monitoring and synchronization, better guarantee the accuracy of time synchronization between power equipment, ensure the precision of phase measurement, line fault location and time sequence recording of power system, and provide technical support for the stable and reliable operation of power system.

Output Control Method of Microgrid VSI Control Network Based on Dynamic Matrix Control Algorithm

In recent years, the power control method of the primary control layer in a microgrid hierarchical control system has substantially improved. However, the corresponding improvement in the dynamic response performance of the output controller remains challenging in the field of microgrid research. In this study, based on the topology of a microgrid control system, a control network was constructed with a voltage source inverter (VSI) control node as its main body. After analyzing its characteristics, the dynamic response capability of the primary layer was determined to be limited because the complex control network that comprises multiple proportional-integral (PI) controllers inherits and amplifies the PI controller dynamics. In this study, we replaced the VSI output controller in the conventional control structure with a dynamic matrix control (DMC) algorithm to reduce the number of PI controllers, maintain the existing power stability control and improve the dynamic response performance of the primary VSI node. The effectiveness and advantages of the improved output controller of the VSI node based on the DMC algorithm were verified by comparing simulations and experiments that were conducted in the same environment. The simulation and experimental results show that the response speed of the DMC-based VSI node was improved, and the overshoot, fluctuation, and steady-state errors in the response process were reduced.

Research on Power Stability Control of Semiconductor Laser

In order to guarantee the stable emission power and good working environment of semiconductor laser, a new hardware circuit is selected and designed to realize automatic optical power control, in which a negative feedback operation amplifier circuit is adopted to form the constant current source, and an optoelectronic feedback to realize closed loop control in this paper. And then, the corresponding steady control circuit is also designed, so that the stable power can be output. The experimental results show that the stability of laser power is better than 0.74% when the system works.