Control Of Operation Modes Research Articles

Analysis of the network structure characteristics of virtual power plants based on a complex network

The topology of the virtual power plant (VPP) operation control mode is the basic theoretical framework for studying some complex problems of VPP systems. Aiming to solve the problem that three classical VPP operation control methods cannot effectively deal with deliberate attacks, a VPP operation control structure with strong survivability is proposed. In order to analyse the invulnerability of the network diagram models of three VPP operation control modes, the characteristic parameters of different network models are compared based on the complex network (CN) theory, and a new VPP operation network model is proposed, which can quickly and comprehensively analyse the VPP structure without relying on various operating states of VPP. Finally, considering the node degree, node betweenness, and edge betweenness, it is verified that the proposed VPP operation control structure has good survivability and can effectively deal with deliberate attacks.

A part-load analysis and control strategies for the Graz Cycle

Carbon capture and storage (CCS) plays a uniquely important role in the future clean and dispatchable power generation portfolio to achieve the ambitious goals set at COP21. The Graz Cycle, a zero emission oxy-combustion power plant, is one of the most promising representatives of CCS power generation plants. The present work introduces different control strategies for the Graz Cycle and the corresponding part-load performances. The process simulation is composed of a design-point (full-load) and off-design (part-load) of the cycle. In order to do this, the process simulation tool IPSEpro was used. Individual cycle components were modelled for both investigations, full load and part load, and control strategies were developed in order to achieve optimum performances and operating efficiencies by means of the assumptions given. This work distinguishes from previous studies by the development of different control strategies and comparison of corresponding part-load performances. In the simulation, the Graz Cycle operating at nominal design conditions achieved a net plant efficiency of 53.1%. The part-load simulation generated results down to 40% load by applying three different control strategies. These control operation modes differ from each other in two basic parameters, boiler pressure and turbine inlet temperature. Optimum part-load performances were achieved by control strategy, where the pressure of the heat recovery steam generator is allowed to vary. However, other parameters, e.g. costs, did not appear to be favourable for this operation mode. The comparison with a readily available technology, such as a natural gas combined cycle, showed that the Graz Cycle is more efficient as loads are reduced below 50%.

Hierarchical Power Allocation Control for Star-Connected Hybrid Energy Storage System Using Cascaded Multilevel Converters

Hybrid energy storage system (HESS) using cascaded multilevel converters (CMC) has received increasing attention due to its merits on smoothing power fluctuations for renewable energy systems (RESs). However, CMC-based HESS still faces tough challenges due to asymmetrical ac power distribution. In this paper, hierarchical power allocation control strategy is utilized in CMC-based star-connected HESS to coordinate power between batteries and supercapacitors (SCs). Using the proposed power allocation mechanism, energy management strategy (EMS) with two operation modes can be achieved, which includes SC voltage regulation mode and power compensation mode. In SC voltage regulation mode, SC voltages are regulated to achieve long-term stable operation. Power compensation mode aims to allocate the active power fluctuation and employs SCs to mitigate it. Meanwhile, the principle of the hierarchical power allocation strategy is analyzed to facilitate the accurate control and flexible switching of different operation modes. A series of simulation and experiment tests are executed to demonstrate the performance of the proposed control strategy.

Methodology of Automated Monitoring and Control of Pump Complex Operation Modes in Conditions of Cavitation Occurrence

The results of solving the problem of increasing the efficiency of an automated pumping complex for pumping liquids in conditions of non-stationary hydraulic processes, such as cavitation, are presented. The difficulty of determining the conditions for the occurrence of cavitation is associated with a large number of parameters, the mutual correlation of which is difficult to determine. It is shown that the methods used in practice in these conditions for monitoring and controlling pumping complexes based on centrifugal pumps and adjacent pipelines have significant disadvantages or solve the problem only partially. A mathematical model of the pump complex operation for operational control of the parameters of cavitation modes based on the similarity of the modes of operation of the centrifugal pump and the movement of the piston through the pipeline is presented, which simplifies the procedure for determining the presence of cavitation. A criterion for determining the efficiency of the pump complex operation mode is proposed based on an integral assessment of the difference between experimental and model data. A methodology for controlling the modes of operation of the pumping complex in the conditions of cavitation is formed. Due to the complexity of the direct calculation of the cavitation volume, a neural network model was proposed, trained based on experimental data. The structure, algorithms and software of the automated control and control system are developed using neural network models and a case-based approach to quickly determine the conditions for the occurrence of cavitation and correct the operating modes of the pumping complex. Decisions based on case — based reasoning are offered to the operator in the form of a "control effect-expected result" pair. The practical implementation of the automated system for monitoring and controlling the operating modes of the pumping complex is carried out in the AppDesigner package of the Matlab mathematical package. The use of the developed automated monitoring and control system provides an increase (restoration) of the pump complex performance in the conditions of cavitation, prevents the destruction of its elements, increases the service life, reduces operating costs and equipment repair costs.

Strong Excitation Control and Stabilization of Operating Modes in a Multi-Machine Power System

Strong Excitation Control and Stabilization of Operating Modes in a Multi-Machine Power System

SYSTEM OF CONTROL OF OPERATING MODES OF ELECTRIC TRACTION NETWORKS ON THE BASIS OF FUZZY DESCRIPTION OF THEIR CONDITION

Given the need to save energy and reduce the cost of passenger transport on urban electric transport, the greatest effect (from 5 to 15%) is achieved through the introduction of comprehensive information technologies based on rational modes of traction of electric rolling stock and traction and external power supply. The criterion for assessing the modes of operation of power supply systems of urban electric transport is the energy consumption of traction substations, which reflects most of the influencing factors, including the inseparable relationship of traction and external power supply systems. An approach to the implementation of energy-saving technologies of traction power supply of urban electric transport is proposed, which uses fuzzy models and methods of representation for analysis and selection of controls. It is proposed to implement the control of the power supply system operation modes and the selection of modes on the basis of a vague description of their states. When forming the rules, the following parameters are set: deviation of the daily number of transported passengers on the i-th interstation zone of the two-track section, for the characterization of which the values ​​of fuzzy values ​​"lag (strong, weak, absent)" and "advance (absent, weak, strong)" deviation of daily active energy losses for the substation zone and with the values ​​"strong, absent, weak"; the difference between the daily energy consumption of the i-th substation zone, for the actual mode of operation of the power supply system and the reference mode of uniform loading of the power supply system. When constructing a control model in the form of fuzzy rules, each fuzzy characteristic is approximated by N fuzzy quantities with triangular membership functions. For the fuzzy characteristic the minimum and maximum values ​​of an interval in which there are its admissible values ​​are set. Approximate quantities have a triangular degree of belonging: the vertex lies in the center, it corresponds to the degree of belonging 1, and the other two vertices - on the sides of it with degrees of belonging 0. The fuzzy conclusion is based on the rule of fuzzy Mamdani implication. The constructed base of fuzzy rules, which replaces the model of modes of the power supply system, can be used as a guide to the energy dispatcher to select control for the next time period, taking into account the conditions of uncertainty. The principles of formation of algorithms and filling of databases and knowledge of expert systems are developed and problems of maintenance of modes of energy saving in systems of traction power supply of city electric transport are solved. The proposed algorithms for creating databases of expert systems can be implemented after the modernization of power supply control systems based on new integrated systems. Expert systems must be included in the software of the automated workplace of the energy dispatcher. Their inclusion is planned after introduction of new microprocessor systems of telemechanics of regional control points.

Study on Optimal Operation of AC-DC Hybrid Distribution Network

With the increase of power load and the access of distributed generation, AC/DC hybrid distribution network will become the development trend of urban distribution network in the future. The core of AC/DC distribution and distributed generation are voltage source converters based on full control switches. This paper simply analyzes the operation principle and control mode of voltage source converters, a power flow calculation method of AC/DC hybrid distribution system is proposed, and the optimization model of AC/DC hybrid distribution network with minimum network loss and minimum voltage deviation of DC network is established. The particle swarm swarm (PSO) algorithm is used to solve the calculation. Considering the load disturbance, the droop control is set for each VSC, at the same time this paper compares the advantages and disadvantages of the whole time optimal power calculation and droop control combined with the optimal power calculation method. Then the control mode of the distribution network is proposed. Finally, an example of PG&E 69-node distribution network in the United States is given to verify the correctness of the proposed model and algorithm.

Tertiary regulation of cascaded run‐of‐the‐river hydropower in the islanded renewable power system considering multi‐timescale dynamics

To enable power supply in rural areas and to exploit clean energy, fully renewable power systems consisting of cascaded run-of-the-river hydropower and volatile energies such as pv and wind are built around the world. In islanded operation mode, the primary and secondary frequency control, i.e., hydro governors and automatic generation control (AGC), are responsible for the frequency stability. However, due to limited water storage capacity of run-of-the-river hydropower and river dynamics constraints, without coordination between the cascaded plants, the traditional AGC with fixed participation factors cannot fully exploit the adjustability of cascaded hydropower. When imbalances between the volatile energy and load occur, load shedding can be inevitable. To address this issue, this paper proposes a coordinated tertiary control approach by jointly considering power system dynamics and the river dynamics that couples the cascaded hydropower plants. The timescales of the power system and river dynamics are very different. To unify the multi-timescale dynamics to establish a model predictive controller that coordinates the cascaded plants, the relation between AGC parameters and turbine discharge over a time interval is approximated by a data-based second-order polynomial surrogate model. The cascaded plants are coordinated by optimising AGC participation factors in a receding-horizon manner, and load shedding is minimised. Simulation of a real-life system with real-time pv data collected on site shows the proposed method significantly reduces load loss under pv volatility.

2모터 2변속기가 장착된 전기구동 자동차의 작동모드 및 모터토크 제어를 통한 에너지 최적화

2모터 2변속기가 장착된 전기구동 자동차의 작동모드 및 모터토크 제어를 통한 에너지 최적화

Study on Optimal Operation Mode of One-key Sequence Control in Substation

At present, some substations have carried out sequential control pilot applications, but there are generally problems such as inconsistent operation methods, narrow operation coverage, incomplete typical functions, and complicated manual intervention links. The article constructs a multi-objective comprehensive evaluation model of operation mode based on the one-key sequential control operation mode of different application scenarios. This article establishes the weights of various indicators including operation efficiency, economic benefits and other factors, conducts a comprehensive evaluation and proposes an optimal operation mode. Through actual cases, the article also analyzes the functional transformation scheme of one-key sequence control technology of intelligent substation.

Impedance-Based Stability Analysis of Less Power Electronics Integrated Electric Shipboard Propulsion System Considering Operation Mode, PLL, and DC-Bus Voltage Control Effect

A doubly-fed induction machine (DFIM) is a promising choice for the shipboard propulsion system (SPS) of a more-electric ship (MES) to increase the system safety level by employing less power electronics. In this paper, the detailed impedance model of DFIM-SPS is established, with a salient-pole synchronous generator (SPSG) acting as the power source and a DFIM functioning as the propulsion load. The impedance modelling of DFIM is carried out from the aspect of ac coupling between the stator and rotor circuits, which is easy for physical understanding. In addition, the back-to-back power converter (BTBPC) is regarded as controlled voltage sources with impedances in the equivalent circuit. The phase-locked loop (PLL) is a key element in influencing the system stability, and it is integrated to upgrade the system dq impedance model. Moreover, the impedance shaping effect caused by dc-bus voltage control is investigated. Nyquist stability criterion is employed for system small-signal stability analysis, which is implemented with respect to the DFIM operation mode and PLL controller effect, and the time-domain simulations are carried out to verify the stable operation of a 5 MW DFIM-SPS in Matlab/Simulink. Furthermore, the experimental verification is done on a 1.5 kW DFIM electric drivetrain platform.

A Design-Oriented Q-V Response Modeling Approach for Grid-Forming Distributed Generators Considering Different Operation Modes

This article presents a design-oriented modeling approach to analyze the <inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> control loop of grid-forming distributed generators (DGs). Unlike previous modeling methods, the proposed approach covers all typical operation modes of grid-forming DGs. No matter which type of inner control scheme is applied, once its state-space model in grid-connected mode is established, the models in islanded single-DG mode and islanded multi-DG mode can be obtained through the proposed formulas. With this novel framework, we analyze and compare two major <inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> control schemes of grid-forming DGs, i.e., the voltage/current double loop-based control, and the reactive power loop-based control, through respective reduced-order models. Closed-loop pole analyses of both control schemes in all three operation modes are investigated to highlight the different features between control schemes and operation modes. These analyses are verified by step-response analyses, which well match corresponding experimental results. The findings of this article help us to better understand the <inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> control loop of grid-forming DGs, e.g., the different features and relations in each operation mode, the pros/cons of the two major control schemes, and the design concerns of inner-loop parameters considering all operation modes.

Опыт организации коммуникационных сетей передачи данных СВИ в системах мониторинга и управления

Changing the characteristics of modern power system associated with the introduction of renewable energy sources and technologies for flexible control of the power system operation mode. This necessitates changing requirements to the functionality of Protection, Automation and Control Systems (PACS). These requirements are based on the need to adapt the PACS algorithms to the new operating conditions of the power system and consider advances in digital technology and information and communication technology. One of the most important conditions for solving this problem is the need to use in PACS the information about the processes of new quality occurring in the power system. Currently, the technology that provides measurement of electric modes parameters of power system with standardized accuracy and time synchronization not exceeding 1 µs, as well as data transmission over arbitrarily long distances with minimal delay and data losses is synchrophasor technology. Development of software based on synchrophasor technology and its implementation for monitoring and control of the electric mode of the power system leads to a constant increase in the amount of data transmitted to the control centers of the System operator and puts forward additional requirements to improve the quality of information received. Therefore, there is a task of maximum use of the resource of existing communication networks, which requires the adoption of complex technical solutions related to the optimization of the architecture of communication networks, improvement of information transfer technologies, organization of automatic life cycle monitoring of PACS (WAMPAC). The paper presents the practical experience and research results of the System operator on the organization of communication networks, providing reliability in the transmission of a large amount of data in real time with the necessary quality for their application in monitoring and control tasks in real time.

A Virtually Coupled Metro Train Platoon Control Approach Based on Model Predictive Control

In this paper, a virtually coupled train formation (VCTF) control method based on the model predictive control (MPC) framework is proposed. The train track spacing error, velocity error, and riding comfort are chosen as the optimization goals, and the constraints of line speed, collision avoidance of the train platoon, traction/braking performance, and string stability are considered. The virtual coupling operation control problem is converted into a quadratic programming problem with constraints. This paper also proposes a coasting control strategy to improve the output of the MPC controller. Simulation results show that compared with the proportional derivative controller, the proposed control method can simultaneously reduce the tracking error and output acceleration, reducing running energy consumption. A study of a metro line is chosen to analyze the VCTF operation performance, and the simulation results show that the VCTF operation mode can improve the peak capacity and quality of service of flat hours compared with the communication-based train control operation mode.

Design and research of cooling system for 2.5 MW permanent magnet wind turbine

In order to solve the problem of excessive temperature rise caused by 2.5 WM permanent magnet wind turbine in operation, this paper designs a heat dissipation system. The combination structure of the heat exchanger and the heat sink was determined, as well as the heat dissipation method of the internal and external cycle isolation heat exchange. The control method and operation mode with Siemens PLC as the core are put forward. The computational fluid dynamics method is utilized to design the air-cooling heat exchanger and the liquid-cooled heat sink of the heat dissipation system. The results show that the cooling pipe gap has a great impact on the liquid cooling effect. The cooling pipe arrangement and piping arrangement of the air-cooled heat exchanger and liquid-cooled radiator are optimized. Finally, taking a 2.5 MW direct-drive permanent magnet wind turbine as an example, four environmental temperatures were selected to test generators in rated power. Verify that the cooling system is designed to meet cooling requirements.

Research on vibration elimination of a 350 MW heat supply unit during cold start

A 350MW heat supply unit in a power plant encountered abnormal vibration of IP rotor bearing during cold start after overhaul. By analyzing the vibration data in the start-up process, the reason for abnormal vibration was found out to be excessive vibration of IP rotor passing through critical speed and rubbing between IP rotor and casing. Through the field high dynamic balancing test and adopting the most suitable operation control mode of this type of heat supply unit, the abnormal vibration of the unit was eliminated.

FEATURES OF ANALYTICAL SYNCHRONIZATION OF DATA OF WORKING PROCESS MONITORING IN TRANSPORT DIESEL ENGINES UNDER OPERATION

The article discusses methods for determining top dead center, based on the analysis of pressure diagrams of a marine engine. The advantages and disadvantages of different methods are shown. Diagnostics of marine engines during operation and selection of optimal operating modes are based on the analysis of pressure diagrams, as well as fuel supply and gas distribution diagrams. As a result of the analysis of the pressure diagrams, the indicator engine power is calculated, which is further used in the control of engine operation modes, in the calculation of specific indicators, as well as in the calculation of energy efficiency coefficients of marine vessels according to IMO recommendations. The influence of the accuracy of determining the position of the top dead center on the calculation of the mean indicated pressure and indicated power is shown. Solving the problem of synchronization of data of working process monitoring using hardware sensors is unacceptable due to the complexity, and sometimes the impossibility of installing hardware sensors for the position of the top dead center of the piston, in addition to the standard sensors. This also leads to a more complex measurement pattern, combined with high accuracy, which is dependent on the load mode. In addition, the installation of hardware sensors is time-consuming and involves organizational problems, as it is necessary to temporarily disable the engine. The mentioned problems are absent in case of analytical data synchronization. It is shown that the existing methods of analytical synchronization are not effective enough for the operating conditions of transport engines. This is mainly due to the complexity of the formulation of the synchronization criteria or their lack of precision due to the impact of noise in the output data. In portable diagnostic systems, the top dead center determination is best done immediately by the analytical method. Principally, there are inconveniences during the diagnosis of engines, because additional pickup sensors and their cables must be used. Before installing the sensors, it is necessary to take the engine out of operation. The installed sensors must be calibrated, which is associated with a significant investment of time. All portable systems for parametric engine diagnostics measure the pressure in the working cylinder through the channel of the indicator valve. In this regard, in portable systems, in addition to the aforementioned errors, errors occur such as throttling and delay of the signal, which leads to an additional shift of the top dead center position. Thus, recently, most modern portable systems for diagnosing marine diesel engines do not use pickup sensors, but use different variants of the analytical determination of top dead center. Diagnostics of marine engines during operating and the selection of optimal operating conditions is based on the analysis of gas pressure diagrams, as well as fuel supply and gas distribution diagrams. As a result of the analysis of the pressure diagrams, the indicator engine power is calculated, which is further used in the management of engine operation modes, in the calculation of specific indicators, as well as in the calculation of energy efficiency coefficients of marine vessels according to International maritime organization recommendations. The authors claimed a method for determining the top dead center, based on solving the equation of equality to zero the first derivative of the gas pressure under compression, which provides the required accuracy in calculating the average indicated pressure and indicator power of the engine during operation. It is shown that the method can be applicable in marine engine working process monitoring systems as an alternative to hardware methods for determining the top dead center.

Research and Design of Operation Mode and Risk Control Model of Finance

The finance warehouse is a kind of service innovation of logistics and finance integration, and its innovative operation mode provides a new channel for SME financing. Firstly, the risk control model of finance warehouse is studied, designed and tested; on the basis of controlling regulatory risk and credit risk, the efficiency coefficient method of evaluation model is adjusted and improved; then the process of operation mode and the characteristics of each mode are studied and designed.

Automatic Control of Operating Modes of Packed Apparatus for Selective Gas Emissions Cleaning

A modified system for automatic control of hydrodynamic operating modes of packed adsorption columns for the selective cleaning of gas emissions is described, which allows automatic adjustment of the operating modes of packed mass transfer apparatus. Presents the scheme and algorithm of developed system with the automatic adjustment (calibration) mode of main operating parameters. The main features and advantages of using elastically deformable blocks of packed material are given on the example of metal chips, i.e. waste of machine tools as a packed material that meet all requirements of the ongoing mass transfer processes and are amenable to automated regulation. The developed system of automatic regulation of parameters of packed units, but also to solve a very serious environmental problem of industrial waste recovery. A classification technique of studying the hydrodynamics of packed materials, capable of concluding the suitability of this sample of packing material for a specific mass transfer process, in particular the adsorption process for the selective cleaning of gas emissions.

Research on coordinated controller design method based on fault early warning model

With increasing degree of power electronics in power system, the interaction between controllers of different FACTS devices poses a greater threat to security and stability of the system. In this paper, a linearized state space model with SVC and STATCOM was established, and the negative interaction mechanism of FACTS device in transient process was analyzed and summarized considering control characteristics, operation mode and setting principle of PI controllers. A model predictive control (MPC) is proposed to replace traditional PI link to establish a coordination controller to overcome the difficulties of PI control parameter setting and global optimization.