提高广东电网自动发电控制应用水平的探讨

通过对广东电网自动发电控制(AGC)运行情况的分析,指出了影响AGC运行的主要原因是目前的控制方式为滞后的控制方式,适用于水电机组占较大比例的电网,而对火电机组占多数的广东电网,目前的控制方式并不能满足要求。为此,针对负荷预测和发电计划的应用,从管理和技术角度提出了水、火电协调的AGC控制方式。采用该方式可提高广东电网AGC运行水平,但具体的调节效果还有待于实际系统运行的验证。     

Automatic generation control of power system using a novel quasi-oppositional harmony search algorithm

The present work approaches a novel quasi-oppositional harmony search (QOHS) algorithm, as an optimization technique, for its optimum performance in the subject area of automatic generation control (AGC) of power system. The proposed QOHS algorithm is applied with an aim to converge rapidly towards the optimal solution(s) that houses both the characters of two guesses, i.e. opposite-point and quasi-opposite point. The area of concern of this study is to discuss the multi-objective problems of an interconnected power system for the benefits of AGC. The proposed QOHS algorithm is, individually, applied to single-area, precede to two-area considering the non-linearity effects of governor dead band and generation rate constraint and, finally, extended to four-area power system showing the consequences of multiple load disturbances. A case of robustness and stability analysis are also investigated for the studied two-area power system model. The control strategy, for the dynamic power system model, is based on area control error. The simplicity of the structure and acceptability responses of the well-known proportional–integral–derivative controller enforces to implement as a controller in this work. The comparative evaluation of the proposed QOHS algorithm is carried out by the way of comparing the dynamic performances of the studied power system model with those offered by other algorithms reported in the recent state-of-the-art literature. The simulation works, presented in the paper, reveal that the proposed QOHS algorithm may be effectively utilized for the purpose of AGC study of power system having varying degrees of complexities and non-linearities. Moreover, the proposed QOHS based control strategy adopted in this work provides a robust and stable speed control mechanism.     

AGC of a multi-area multi-source hydrothermal power system interconnected via AC/DC parallel links under deregulated environment

This paper proposes the automatic generation control (AGC) of an interconnected multi-area multi-source hydrothermal power system under deregulated environment. The two equal control areas with hydro and thermal generating power sources are interconnected via AC/DC parallel links. The optimal proportional integral (PI) regulators are designed for the proposed power system to simulate all power market transactions which are possible in a restructured power system. The concept of DISCO participation matrix (DPM) is harnessed to simulate the transactions. Eigenvalue study is conducted to assess the effect of AC/DC parallel links on system performance. The study is also conducted, considering appropriate generation rate constraints (GRCs) for thermal and hydro generating sources. Further, the dynamic responses of the proposed multi-source hydrothermal power system are compared with single-source thermal–thermal power system and it has been ascertained that the responses of proposed power system are sluggish with large overshoots and settling times. Finally, the study is extended to frame and implement optimal PI regulators for the first time for the AGC of a conventional two-area non-reheat thermal power system with governor dead-band nonlinearity. The superiority of the optimal PI regulators has been established by comparing the results with recently published best claimed craziness based particle swarm optimization (CRAZYPSO) and hybrid bacterial foraging optimization algorithm-particle swarm optimization (hBFOA-PSO) algorithms based PI controller tuned for the same interconnected power system.     

Application of capacitive energy storage for transient performance improvement of power system

In this paper, a comparative transient performance of two types of single machine power system is analyzed. The two types of system configurations are viz. (i) automatic voltage regulator (AVR) loop with single input conventional power system stabilizer (CPSS) combined with automatic generation control (AGC) loop, (ii) AVR with CPSS combined with capacitive energy storage (CES) unit-based AGC loop. For AGC loop both thermal unit and hydro unit are individually considered. The thermal unit is considered with either single or double stage reheat turbine, hydro unit is considered with mechanical or electric governor. Integral controller is provided in the AGC loop. It is shown that the CES-based integral controlled AGC loop along with CPSS assists in the best transient performance of the power system in all cases under different operating conditions. Parameters of the CPSS installed in AVR loop, gains of the integral controller in AGC loop are optimized with the help of a novel particle swarm optimization, developed by the authors, called as craziness-based particle swarm optimization (CRPSO). Transient performance is carried out with 1% step perturbation in either reference voltage or load torque.     

Automatic Generation Control in an Interconnected Power System Incorporating Diverse Source Power Plants Using Bacteria Foraging Optimization Technique

This article presents automatic generation control (AGC) of a two-area interconnected power system with diverse energy sources using the bacteria foraging optimization technique. The control areas of interconnected power systems consist of hydro, thermal, and gas power plants. In this study, the proportional-integral-derivative (PID) structures of AGC regulators are designed for various case studies identified herein. An artificial intelligent optimization algorithm using the modeling behavior of E. Coli bacteria present in human intestines, is applied to tune the gains of PID structured AGC regulators. The closed-loop system dynamic response plots are obtained with designed AGC regulators for various power system models. The effectiveness of the proposed AGC regulators is demonstrated in the wake of a 1% step load disturbance in one of the control areas. It has been shown that the system dynamic responses subject to a step load disturbance are superior over other power plant combinations in a control area with only thermal and gas power plants participating in the AGC schemes, and it is sluggish/poor when only hydro power plants participated in the AGC scheme as one of the diverse sources in the power system.     

计及大规模电动汽车接入的AGC功率动态分配深度交互教学优化算法

为提高区域电网自动发电控制(automatic generation control,AGC)的控制性能指标,利用接入电网的大规模电动汽车参与AGC。在满足车主充电需求的前提下,建立了电动汽车的实时上下调节容量评估模型。在此基础上,构建了电动汽车集群与传统水电、火电机组的AGC功率分层分配框架。为满足上层不同类型机组的快速经济分配,提出了一种深度交互教学(deep interactive teaching-learning,DITL)优化算法进行求解,该算法在标准教学优化算法的基础上,将单个班级扩展到多个班级,并采用小世界交互网络构建不同教师/学生之间的交互网络,从而提升算法的全局搜索及局部搜索能力。在电动汽车集群内部,则根据调节成本系数实现第二层不同局部控制中心的AGC功率分配,然后根据充电时间裕度排序实现不同电动汽车的底层AGC功率分配。海南电网仿真算例表明:该文所提的上层分配框架可有效实现电动汽车与传统水火电机组的协调,DITL算法能有效提升AGC的动态控制性能,降低系统的调节成本。     

Load frequency control of a realistic power system with multi-source power generation

In this paper, load frequency control (LFC) of a realistic power system with multi-source power generation is presented. The single area power system includes dynamics of thermal with reheat turbine, hydro and gas power plants. Appropriate generation rate constraints (GRCs) are considered for the thermal and hydro plants. In practice, access to all the state variables of a system is not possible and also their measurement is costly and difficult. Usually only a reduced number of state variables or linear combinations thereof, are available. To resolve this difficulty, optimal output feedback controller which uses only the output state variables is proposed. The performances of the proposed controller are compared with the full state feedback controller. The action of this proposed controller provides satisfactory balance between frequency overshoot and transient oscillations with zero steady state error in the multi-source power system environment. The effect of regulation parameter (R) on the frequency deviation response is examined. The sensitivity analysis reveals that the proposed controller is quite robust and optimum controller gains once set for nominal condition need not to be changed for ±25% variations in the system parameters and operating load condition from their nominal values. To show the effectiveness of the proposed controller on the actual power system, the LFC of hydro power plants operational in KHOZESTAN (a province in southwest of Iran) has also been presented.     

A new technique in hydro thermal interconnected automatic generation control system by using minority charge carrier inspired algorithm

This article deals with Automatic Generation Control (AGC) of a multi area interconnected hydro thermal system in different modes using intelligent integral and proportional-integral controllers and provides the comparative analysis of electrical and mechanical governors. Appropriate Generation Rate Constraints (GRC) has been considered for the hydro and thermal generation plants. These cumulated thermal areas are considered with reheat turbines. Performances of reheat turbine mechanical governor and hydro turbine electrical governor with its dynamic responses have been investigated. Further, selection of suitable integral and proportional-integral controllers has been investigated with a Minority Charge carrier Inspired Algorithm (MCI). Cumulative system performance is examined considering with different load perturbation in both cumulative thermal areas. Further, system is investigated with different frequency bias values and results are explored.     

Application of Hybrid Differential Evolution–Grey Wolf Optimization Algorithm for Automatic Generation Control of a Multi-Source Interconnected Power System Using Optimal Fuzzy–PID Controller

This paper deals with an optimal hybrid fuzzy-Proportional Integral Derivative (fuzzy-PID) controller optimized by hybrid differential evolution–Grey Wolf optimization algorithm for automatic generation control of an interconnected multi-source power system. Here a two area system is considered; each area is provided with three types of sources namely a thermal unit with reheat turbine, a hydro unit and a gas unit. The dynamic performance of the system is analyzed under two cases: with AC tie-line and with AC-DC tie-line. The efficiency and effectiveness of the proposed controller is substantiated equally in the two cases. The sturdiness of the system is proved by varying the values of the system parameters. The supremacy of the recommended work is additionally ascertained by comparison with the recently published results like differential evolution optimized PID Controller and hybrid Local Unimodal Sampling-Teaching Learning based Optimization (LUS-TLBO) optimized fuzzy-PID controller. The dynamic performance of the system is observed in terms of settling time, peak overshoot and peak undershoot. Finally the analysis is extended by applying the proposed control technique in two different models namely (i) A three area unequal thermal system considering proper generation rate constraints (GRC) and (ii) A three area hydro-thermal system with mechanical hydro governor. These test results reveal the adaptability of the proposed method in multi-area interconnected power system.     

提高火电机组AGC性能的方法研究

论述了火电机组自动发电控制（AGC）功能对协调控制系统（CCS）的性能要求,分析了发电机组调节速率不能满足要求的主要原因。并以广东某电厂3号机组为例,分析了CCS存在的主要问题,提出了增加负荷指令-燃料量指令的动态前馈功能,以提高火电机组AGC性能。试验结果表明,该方法对提高火电机组AGC性能有显著效果。     

TLBO optimized sliding mode controller for multi-area multi-source nonlinear interconnected AGC system

This paper represents design of output feedback sliding mode controller (SMC) for multi area multi-source interconnected power system. After designing output feedback SMC, teaching and learning based optimization (TLBO) technique is utilized to optimize feedback gain and switching vector of the controller. The superiority of the proposed approach is shown by comparing the result with output feedback tuned SMC with differential evolution and particle swarm optimization and state feedback SMC tuned with genetic algorithm for a two area thermal interconnected power system. Further, the proposed approach is extended to multi-area multi-source non linear automatic generation control (AGC) system with/without HVDC link. First area consists up thermal, hydro and gas; second area consists up thermal, hydro and nuclear as generating unit. Additionally, the superiority of proposed approach is shown by sensitivity analysis, which is carried out with wide changes in system parameters.     

Cascade controller based modeling of a four area thermal: gas AGC system with dependency of wind turbine generator and PEVs under restructured environment

This paper investigates automatic generation control (AGC) of a realistic hybrid four-control area system with a distinct arrangement of thermal units, gas units and additional power generation. A proportional-integral-double derivative cascaded with proportional-integral (PIDD-PI) controller is employed as secondary controller in each control area for robust restructured AGC considering bilateral transactions and contract violations. The Harris Hawks algorithm is used to determine the optimal controller gains and system parameters under several scenarios. Electric vehicle (EV) aggregators are employed in each area to participate fully along with thermal and gas units to compensate for the unscheduled system demand in the local area. A comparison of non-cascaded controllers such as PI-PD, PD-PID and the proposed PIDD-PI proves the superiority of the last. The effect of the decline in inertia is closely examined because of the sudden outage of a generating unit while at the same time considering the change in area frequency response characteristics and area control error. EV fleets make significant contributions to improving the system dynamics during system inertia loss. The use of EVs in the presence of a wind energy-supported grid can provide a stable efficacy to the power grid. Numerous simulations with higher load demands, stochastic communication delays in presence of the WTG plant, and violations in system loadings and changes in gas turbine time constants in the absence of WTG demonstrate the robustness of the proposed control approach.     

大型火电机组在AGC运行方式下的控制特性分析

结合华北电网自动发电控制(AGC)的实际运行情况,介绍了AGC控制方式、华北电网对AGC投运机组的控制指标要求以及机组的协调控制系统设计方案,分析了华北电网中的大型火电机组在AGC运行过程中遇到的问题,并提出了提高机组在AGC运行方式下的控制特性的方法和建议.     

海南电网AGC超前控制

为了改善海南电网自动发电控制(automatic generation control,AGC),充分发挥火电机组调节性能,基于超短期负荷预测原理建立了海南电网AGC超前控制模型。利用该模型和线性外推法可以预测未来一段时间内每隔5 min的系统负荷,并根据预测自动调整机组发电计划。在两个电厂的火电机组试验结果表明,所提出的AGC超前控制可以改善海南电网的调节质量。     

Possibilistic programming approach for mid-term electric power planning in deregulated markets

The mid-term electric power planning problem under uncertainty for a generation company (GenCo) in a deregulated market having some thermal, hydro and wind power plants is addressed. We propose a novel possibilistic price-based mixed integer linear programming approach to solve the considered problem. Because the uncertainties especially those are related to market could not usually be based upon probabilities, the possibilistic distribution functions are used to simulate some key imprecise/ambiguous parameters: GenCo’s electricity market share; electricity, fuel and emission market prices; possible wind electric power; availability of generating units; available water reservoir for hydro units. To solve the proposed model, we develop an interactive possibilistic solution method based upon two recent solution approaches. Finally, we use a real-world case study to show the ability and appropriateness of our model and report computational results. Notably, the proposed approach can be easily applied for a regulated environment.     

超临界火电机组运行灵活性提升控制策略研究及应用

新能源发电装机容量和区外远距离供电量的不断增长,电网供电结构发生了根本性变化,导致调峰压力不断加大,对火力发电机组自动控制灵活性改造的要求也因此逐步提高。通过对电网AGC指令特点分析,并研究超临界火电机组的控制特性,按照电网日趋严格的调度要求,提出了提高宽负荷下机组负荷响应速率、避免AGC指令小幅波动对机组控制的影响,以及提高再热汽温控制稳定性等一系列优化策略。经过实际应用证明,优化后的协调控制系统可以在保证机组主要热力参数稳定的基础上,很好地满足电网对火电机组运行灵活性提升的考核要求。     

Mixed integer programming of generalized hydro-thermal self-scheduling of generating units

This paper presents the application of mixed-integer programming (MIP) approach for solving the hydro-thermal self scheduling (HTSS) problem of generating units. In the deregulated environment, the generation companies schedule their generators to maximize their profit while satisfying loads is not an obligation. The HTSS is a high dimensional mixed-integer optimization problem. Therefore, in the large-scale power systems, solving the HTSS is very difficult. In this paper, MIP formulation is adopted for precise modeling of dynamic ramp rate limits, prohibited operating zones, operating services, valve loading effects, variable fuel cost, non-linear start-up cost functions of thermal units, fuel and emission limits of thermal units, multi head power-discharge characteristics of hydro plants and spillage of reservoir. The modified IEEE 118-bus system is used to demonstrate the performance of the proposed method.     

660 MW超临界燃煤机组变负荷过程动态特性的仿真研究

燃煤机组变负荷速率的提升是电网AGC（automatic generation control）调节过程灵活性的重要评价指标。建立了660 MW超临界一次再热燃煤机组的动态仿真模型,并嵌入了详细热工控制模型,获得了75%~100%THA范围内不同变负荷速率下的机组主要热力参数的动态变化规律。利用工质最大温度偏差和平均标准煤耗率差值为评价指标,对燃煤机组AGC变负荷过程的安全性和经济性开展了分析。研究结果表明：随着变负荷速率的提高,输出功率、主汽温度和再热蒸汽温度波动越来越剧烈,水冷壁出口、屏式过热器出口、水平低温再热器入口和垂直低温再热器出口的工质最大温度偏差逐渐增大,最大值分别为24.7、29.1、26.1和41.3 ℃。随着升负荷速率的提高,平均标准煤耗率差值逐渐减小,变化范围为2.35~2.53 g/（kW·h）,随着降负荷速率的提高,平均标准煤耗率差值的绝对值逐渐减小,变化范围为-2.64~-2.50 g/（kW·h）。     

电力市场下基于改进遗传算法的AGC机组的选择

针对电力市场下参与竞标的各自动发电控制（AGC）机组的选择问题,提出了一种基于实数和二进制数混合编码、个体分段交叉变异的改进遗传算法。该算法采用实数模拟AGC机组的调节容量,无需解码,具有较高的收敛精度,同时采用二进制编码模拟AGC机组中标状态,充分利用了两种编码方式的优点;对群体中的个体采用了轮盘赌选择,并按容量段、状态段分别进行交叉、变异的遗传操作方法,较好地解决了电力市场下AGC机组选择这一0—1混合整数非线性规划问题。最后通过对某省实际电网的算例分析,验证了该算法的可行性。     

SELECTION OF SAMPLING PERIOD FOR AUTOMATIC GENERATION CONTROL

ABSTRACT

The paper presents the analysis of automatic generation control (AGC) of a two-equal area reheat thermal system in the presence of generation rate constraints considering a discrete-continuous time mathematical model. The effect of variation of sampling period on optimum integral gain setting and system dynamic performance has been analyzed considering supplementary controllers based on conventional area control errors (ACEs) and new area control errors (ACENs). Investigations reveal that the optimum integral gain setting and system dynamic performance are hardly affected over a wide range of sampling period T for controllers based on conventional ACEs. Studies also reveal that the permissible sampling period is further enhanced with integral controllers based on new area control errors (ACENs).