Dead Band Research Articles

Equivalent Modeling of Inverter Air Conditioners for Providing Frequency Regulation Service

The frequency regulation service (FRS) is playing an increasingly important role in maintaining the power balance between generation and consumption. Moreover, the recent progress in information and communication technologies has enabled residential customers to participate in FRS through direct control over appliances, such as inverter air conditioners (ACs), whose market share is growing rapidly and has made up a large fraction of electricity consumption. Inverter ACs can change compressor's speed continuously to adjust operating power and provide FRS for the system operation. In this paper, the thermal model of a room and the electrical model of an inverter AC for providing FRS are developed. The model of the inverter AC is equivalent to a generator. In this manner, the aggregation of inverter ACs can be controlled just as traditional generators. Besides, a stochastic allocation method of the regulation sequence among inverter ACs is proposed to reduce the effect of FRS on customers. A hybrid control strategy by taking into account the dead band control and the hysteresis control is also developed to reduce the frequency fluctuations of power systems. The effectiveness of the proposed models and control strategies is illustrated in the numerical studies.

High-performance fully differential photodiode amplifier for miniature fiber-optic gyroscopes.

Electrical cross coupling is regarded as a major obstacle to achieving high-performance miniature fiber-optic gyroscopes (FOGs), because it can cause dead bands, which are critical errors in FOGs. Using a differential photodiode amplifier has proven to be effective in rejecting coupled interference. However, the conventional three-op-amp instrumentation amplifier cannot provide a miniature FOG's bandwidth requirements, because of the large photodiode capacitance and parasitic capacitance. We present a high-performance, fully differential photodiode amplifier, where the bandwidth limitations are removed by applying a reverse bias to the photodiode and replacing the feedback resistor with a modified tee-network and a DC cancellation loop. For an experimental FOG with a 300 m fiber coil, we demonstrate a fully differential photodiode amplifier with 880 kΩ gain and 3.5 MHz bandwidth. In the FOG performance test, it not only reduces the angular random walk and bias drift, but also eliminates the approximately 1°/h dead band observed in the same FOG using a PINFET receiver, demonstrating its effectiveness in suppressing coupled interference.

Equation-based object-oriented modeling and simulation for data center cooling: A case study

Data center cooling accounts for about 1% of electricity usage in the United States. Computer models are pivotal in designing and operating energy-efficient cooling systems. Compared to conventional building performance simulation programs, the equation-based object-oriented modeling language Modelica is an emerging approach that can enable fast prototyping and dynamic simulation of cooling systems. In this case study, we first modeled the cooling and control systems of an actual data center located in Massachusetts using the open-source Modelica Buildings library, and then calibrated a baseline model based on measurement data. The simulation of the baseline model identified several operation-related issues in the cooling and control systems, such as degraded cooling coils, improper dead band in control settings, and simultaneous cooling and heating in air handlers. Afterwards, we used a sequential search technique as well as an optimization scheme to investigate the energy saving potentials for different energy efficiency measures aiming to address the abovementioned issues. Simulation results show potential energy savings up to 24% by resolving identified control-related issues and optimizing the supply air temperature.

Design an optimal fuzzy fractional proportional integral derivative controller with derivative filter for load frequency control in power systems

In this article, a novel fuzzy proportional integral derivative (PID) controller with filtered derivative action and fractional order integrator (fuzzy PIλDF controller) is proposed to solve automatic generation control (AGC) problem in power system. The optimization task for fine-tuning parameters of the proposed controller structure is accomplished by cuckoo optimization algorithm (COA). To appraise the usefulness and practicability of proposed COA optimized fuzzy PIλDF controller, four extensively used interconnected test systems, that is, two-area non-reheat thermal, two-area multi-source, three-area thermal and three-area hydro-thermal power plants, are considered. Different nonlinearity such as generation rate constraint (GRC) and governor dead band (GDB) as a source of physical constraints are taken into account in the model of the three-area power systems to examine the ability of the proposed technique to handle practical challenges. The acceptability and novelty of COA-based fuzzy PIλDF controller to solve aforesaid test systems are evaluated in comparison with some recently reported approaches. The consequences of time domain simulation reveal that designed secondary controllers provide a desirable level of performance and stability compared with other existing strategies. Additionally, to explore the robustness of the proposed technique, sensitivity analysis is conducted by varying the operating loading conditions and system parameters within a specific tolerable range.

Load frequency control enhancement of islanded micro-grid considering high wind power penetration using superconducting magnetic energy storage and optimal controller

This article proposes a robust load frequency control using a new optimal proportional–integral–derivative controller–based genetic moth swarm algorithm for islanded microgrids considering high wind power penetration. In such microgrids, the replacement of conventional generator units with a large number of renewable energy sources reduces the system inertia, which in turn causes undesirable influence on microgrid frequency stability, leading to weakening of the microgrid. Furthermore, sudden load shedding, load restoring, and short circuits caused large frequency fluctuations which threaten the system security and could lead to complete blackouts as well as damages to the system equipment. In order to solve this challenge, this study proposes a new coordinated optimal load frequency control plus modified control signal to superconducting magnetic energy storage for compensating the microgrid frequency deviation (∆ f). To prove the effectiveness of the proposed coordinated control strategy, an islanded microgrid was tested for the MATLAB/Simulink simulation. The physical constraints of the turbines such as generation rate constraints and speed governor dead band are considered in this study. The results confirmed the effectiveness and robustness of the proposed coordination performance against all scenarios of different load profiles, wind power fluctuation, and system uncertainties in microgrid integrated with high penetration of wind farms. Moreover, the results have been compared with both: the optimal load frequency control with/without the effect of conventional superconducting magnetic energy storage.

High-Gain Dead-Zone Observers for Linear and Nonlinear Plants

We propose an adaptive dead-zone mechanism to robustify observers against high-frequency noise. The construction applies to Luenberger observers and high-gain observers for plants in strict feedback form. The dead-zone improves performances by trimming a portion of the output injection term and trapping the high frequency noise in the dead band. We show that the observer gain and the adaptation parameters can be obtained by solving a linear matrix inequality, whose feasibility only requires detectability of the plant. The parameters obtained through this optimization ensure (in the absence of noise) global exponential stability of the estimation error dynamics, and input-to-state stability from the measurement noise to the estimation error.

An intelligent coordinator design for GCSC and AGC in a two-area hybrid power system

This study addresses the design procedure of an optimized fuzzy fine-tuning (OFFT) approach as an intelligent coordinator for gate controlled series capacitors (GCSC) and automatic generation control (AGC) in hybrid multi-area power system. To do so, a detailed mathematical formulation for the participation of GCSC in tie-line power flow exchange is presented. The proposed OFFT approach is intended for valid adjustment of proportional–integral controller gains in GCSC structure and integral gain of secondary control loop in the AGC structure. Unlike the conventional classic controllers with constant gains that are generally designed for fixed operating conditions, the outlined approach demonstrates robust performance in load disturbances with adapting the gains of classic controllers. The parameters are adjusted in an online manner via the fuzzy logic method in which the sine cosine algorithm subjoined to optimize the fuzzy logic. To prove the scalability of the proposed approach, the design has also been implemented on a hybrid interconnected two-area power system with nonlinearity effect of governor dead band and generation rate constraint. Success of the proposed OFFT approach is established in three scenarios by comparing the dynamic performance of concerned power system with several optimization algorithms including artificial bee colony algorithm, genetic algorithm, improved particle swarm optimization algorithm, ant colony optimization algorithm and sine cosine algorithm.

Improving the dynamic frequency regulation of a multisource power system considering GRC and dead band with TCSC and SMES

Coordinated operation of superconducting magnetic energy storage (SMES) and thyristor controlled series compensator (TCSC) for dynamic frequency regulation on a multisource power system is presented in this paper. The optimal integral gains of the control areas are obtained by tuning a quadratic performance index consisting of frequency deviations and tie-line power error using integral squared error technique. The effects of generation rate constraint and governor dead band nonlinearities are also considered. Time domain simulations carried out in MATLAB on a sample two area multi-unit power system comprising hydro, thermal and gas power plants reveal that the SMES-TCSC combination can effectively damp out deviations in area frequencies and tie-line power flow following a sudden load perturbation with better transient performance and reduced settling time.

Исследование модифицированной стратегии последовательного хеджирования с наклонной полосой нечувствительности

In this article The stop-loss start-gain strategy modification with tilt deadband is studied. The top line of this band is tilted. During the research mathematical model with discrete pricing process was examined. The increments of this process have a normal distribution with a constant nonzero mean and constant dispersion. The article considers the distribution of the number of intersections of a nonrectilinear strip by a discrete Gaussian walk. Formulas that allow to specify the distribution of the number of intersections of the strip in the directions “bottomup” and “top-down” were deduced. An algorithm was developed to calculate the number of these intersections and evaluate the conditional probability of the transition. In addition, the dependence of the average hedger losses while using this strategy on the slope coefficient of the upper boundary of the dead band and the band width was considered. Using the Monte Carlo simulation, an algorithm was developed to find the optimal width and slope of the strip. During the numerical experiments, the dependence was revealed and the optimal slope coefficient was determined for the given parameters. Experimental work confirmed the correctness of the proposed algorithms and proved the effectiveness of this modification in comparison with the use of a strategy with a straight strip.

Improving the dynamic frequency regulation of a multisource power system considering GRC and dead band with TCSC and SMES

Coordinated operation of superconducting magnetic energy storage (SMES) and thyristor controlled series compensator (TCSC) for dynamic frequency regulation on a multisource power system is presented in this paper. The optimal integral gains of the control areas are obtained by tuning a quadratic performance index consisting of frequency deviations and tie-line power error using integral squared error technique. The effects of generation rate constraint and governor dead band nonlinearities are also considered. Time domain simulations carried out in MATLAB on a sample two area multi-unit power system comprising hydro, thermal and gas power plants reveal that the SMES-TCSC combination can effectively damp out deviations in area frequencies and tie-line power flow following a sudden load perturbation with better transient performance and reduced settling time.

Whale optimisation algorithm tuned fractional order PI<SUP align="right">λ</SUP>D<SUP align="right">μ</SUP> controller for load frequency control of multi-source power system

This paper deals with the design and optimisation of a fractional order PIλDμ (FOPID) controller implemented for load frequency control (LFC) of a multi-area multi-source power system having the nonlinearities of time delays, generation rate constraint (GRC) and governor dead band (GDB). Whale optimisation algorithm (WOA), arguably for the first time in this area, is applied for optimal tuning of the parameters of FOPID controller. The comparative analysis of the performance of WOA vis-a-vis other recent evolutionary optimisation approaches is carried out from which it is observed that WOA optimised FOPID controller gives the best dynamic performance in terms of settling time and maximum overshoot in frequency and tie-line power deviations. Further, investigations carried out against system parametric variations within the range of ± 25% reveal that WOA tuned FOPID controller is the most effective and robust against wide variations in system parameters.

Black hole optimised cascade proportional derivative-proportional integral derivative controller for frequency regulation in hybrid distributed power system

This manuscript presents a novel black hole optimised (BHO) proportional derivative-proportional integral derivative controller (PD-PID) is provided for the optimal solution of the frequency regulation of hybrid power system. At first, a two area power system is considered in which area-1 having thermal, distributed units and in area-2 includes thermal, hydel and nuclear units. Appropriate nonlinearities such boiler dynamics, governor dead band (GDB) and generation rate constraint (GRC) are considered. In the next step, PD-PID controller is considered as a secondary controller and its preeminence is shown by comparing with proportional integral derivate (PID) and proportional integral double derivate (PIDD) controllers for the same model having integral time multiplied absolute error (ITAE) as an error function. Finally, sensitivity of the proposed controller is investigated over a wide variation of system parameters and loading condition. For more examination of the proposed controller is also analysed under random step load and sinusoidal disturbances.

Black hole optimised cascade proportional derivative-proportional integral derivative controller for frequency regulation in hybrid distributed power system

This manuscript presents a novel black hole optimised (BHO) proportional derivative-proportional integral derivative controller (PD-PID) is provided for the optimal solution of the frequency regulation of hybrid power system. At first, a two area power system is considered in which area-1 having thermal, distributed units and in area-2 includes thermal, hydel and nuclear units. Appropriate nonlinearities such boiler dynamics, governor dead band (GDB) and generation rate constraint (GRC) are considered. In the next step, PD-PID controller is considered as a secondary controller and its preeminence is shown by comparing with proportional integral derivate (PID) and proportional integral double derivate (PIDD) controllers for the same model having integral time multiplied absolute error (ITAE) as an error function. Finally, sensitivity of the proposed controller is investigated over a wide variation of system parameters and loading condition. For more examination of the proposed controller is also analysed under random step load and sinusoidal disturbances.

Efficiency in Heating Operation of Low-Temperature Radiant Systems Working under Dynamic Conditions in Different Kinds of Buildings

In recent years many types of radiant systems have been installed in buildings. Meanwhile, practitioners debate on which thermal inertia of radiant systems fit better and which control strategies should be better in buildings, depending on the insulation level and thermal inertia of the structures. In particular, in new and retrofitted buildings, where the envelope presents high levels of insulation, it is argued if it is better to have low or high inertia radiant systems for controlling the indoor operative temperature and avoid overheating, especially in mid-seasons when the outdoor temperature is mild and solar radiation is high. For this purpose a room with three types of insulation level has been analysed combining different types of structures (masonry, and light and timber walls) and three types of radiant systems (classic wet floor, dry floor, and ceiling). Two operation modes have been simulated: fixed supply temperature and variable temperature according to the outdoor temperature. The results looked at the embedded and control efficiency, the energy performance in case of coupling with a water to water heat pump and the long-term possible overheating analysis. The embedded and control efficiency in dynamic conditions has been evaluated and compared with different possible definitions, in particular with steady state conditions, former EN15316-2-2007, and current EN15316-2-2017. New values for the current standard are suggested based on the results of this work, since the former and existing values overestimate the seasonal losses of floor and radiant systems in heating conditions. The paper shows that working at variable temperature according to the outdoor air temperature leads to longer operation time. The temperature, on average, lowers, and coupling the radiant system with a water to water heat pump leads to lower consumptions in the case of variable supply temperature compared to fixed supply temperature over the season. The seasonal coefficient of performance of the whole system, i.e. the heat pump and auxiliary pumps, leads to overall lower energy consumption in the case of variable supply temperature. The simulations did not show any relevant problem of discomfort from December to February. Overtemperature effects in terms of operative temperatures over the dead band of the control systems are not especially due to the radiant system, but they also occur in any case with ideal convective systems. The paper demonstrates that in general the radiant floor systems perform better than radiant ceilings in heating conditions and there is no evidence that dry floor systems perform better than wet screed systems in all the types of buildings regardless of the level of insulation and thermal inertia.

A Moth–Flame Optimization for UPFC–RFB-Based Load Frequency Stabilization of a Realistic Power System with Various Nonlinearities

In this article, a realistic multi-area multi-source test power system model is investigated by imposing the effects of nonlinearities for the betterment of automatic generation control (AGC) realization. The confined area of presented work is to cogitate the effectiveness of combined unified power flow controller (UPFC) and redox flow battery (RFB) in view of damping of oscillations subjected to increased load perturbation. The investigated power system model is a six-area system having reheat thermal, hydro and gas-generating units lumped together in each control area. The present prospect analyzes a very realistic approach of AGC by adding physical constraints like time delay, governor dead band, boiler dynamics, reheat turbine and generation rate constraint to the aforesaid system. A nature-inspired novel moth–flame optimization (MFO) algorithm is employed as an optimization tool in the design of proportional–integral–derivative gains and the tunable parameters of UPFC and RFBs. The substantial point of discussion is the guaranteed convergence mobility as the moths in this algorithm update their positions with respect to the flames which represent the most promising solutions. The MFO-based results are compared with genetic algorithm-based method to show the superiority of MFO over other similar metaheuristic optimization techniques. Robustness of the designed controller is also studied over ± 25% uncertainties in parametric values and under loaded condition. The simulation works showed that the inclusion of UPFC and RFB is very much effective in load frequency stabilization and is quite robust for a realistic power system.

Load frequency control of a dynamic interconnected power system using generalised Hopfield neural network based self‐adaptive PID controller

A novel generalised Hopfield neural network (GHNN) based self-adaptive proportional–integral–derivative (PID) controller for load frequency control (LFC) is designed for a two-area interconnected power system with nonlinearities of generator rate constraint and governor dead band. The control problem is conceptualised as an optimisation problem with an objective function as an area control error in terms of the PID controller parameters. The differential equations governing the behaviour of the GHNN were solved to obtain the controller parameters Kp, Ki and Kd. To test the feasibility and robustness of the proposed controller, the system is tested in the presence of randomness in load demands, imprecisely modelled system dynamics, nonlinearities in the system model and uncertainties in the system parameter variations. The proposed method is simulated using Matlab R2014b/Simulink and the results obtained have shown that the propounded controller performance is superior to the integral, PID and fuzzy-based proportional–integral controllers. In addition, the Lyapunov stability analysis of the overall closed-loop system was carried out and the controller is implemented in real-time digital simulator run in hardware-in-the-loop to validate the effectiveness of the proposed method. Furthermore, the proposed controller is applied to the three-area power system to test its adaptability.

Вплив зони нечутливості та швидкодії регулятора на процес стабілізації частоти в енергосистемі з потужними вітровими електростанціями та акумуляторними батареями

Вплив зони нечутливості та швидкодії регулятора на процес стабілізації частоти в енергосистемі з потужними вітровими електростанціями та акумуляторними батареями

Tensor CSAMT and AMT Studies of the Xiarihamu Ni-Cu Sulfide Deposit in Qinghai, China

The frequency domain electromagnetic sounding method is one of the important means of exploring mineral resources. This paper combined tensor controlled source audio frequency magnetotelluric (CSAMT) and audio frequency magnetotelluric(AMT) methods to investigate Xiarihamu copper‑nickel ore in Qinghai Province. Spliced tensor CSAMT high frequency (200 Hz–8533 Hz) and AMT low frequency (1 Hz–200 Hz) apparent resistivity and impedance phase data, as well as spliced data, were used for a 2D inversion and to generate a 2D geoelectric model. Coupled with the known geological, geophysical, and drilling data, the inversion results were analyzed. The results show that the combined use of tensor CSAMT and AMT can overcome the inherent defects of these methods, such as limited exploration depth and the “dead band” effect. This method produced good results in terms of exploring the underground electrical structure, finding the low resistivity body, and determining the thickness of the overburden, as well as the occurrence and the buried depth of the ore body. These results provide an effective method and exploration strategy to find similar potential deposits in the surrounding areas.

Comparative performance analysis of 2DOF state feedback controller for automatic generation control using whale optimization algorithm

SummaryThis paper presents the design of two‐degree‐of‐freedom state feedback controller (2DOFSFC) for automatic generation control problem. A recently developed new metaheuristic algorithm called whale optimization algorithm is employed to optimize the parameters of 2DOFSFC. The proposed 2DOFSFC is analyzed for a two‐area interconnected thermal power system including governor dead band nonlinearity and further extended to multiunit hydrothermal power system. The supremacy of the 2DOFSFC is established comparing with proportional‐integral, proportional‐integral‐derivative (PID), and 2DOFPID controllers optimized with different competitive algorithms for the concerned system. The sensitivity analysis of the optimal 2DOFSFC is performed with uncertainty condition made by varying bias coefficient B and regulation R parameters. Furthermore, the proposed controller is also verified against random load variations and step load perturbation at different locations of the system.

RANCANG BANGUN PERANGKAT PEMBANGKIT PWM BIPOLAR

Electrical power settings, both AC and DC can be done by linear or switching. Controlled loads may be motors, heating elements or incandescent lamps. Generally the efficiency of load power control by way of switching is better than linear way so the way switching is widely used today. Switching also allows for automatic, remote and wireless control In load power management system with microcontroller, PWM generator circuit output is used for control of power switch. The output pulse can be TTL standard or with lower amplitude and on the control of the H bridge circuit required bipolar PWM with additional dead band on each side of the pulse ride. The bipolar PWM generator designed in this study has an output with TTL standard with a dead band circuit and a short circuit protection for VCC = 5 volts and a ground path, Testing with no load and short circuit in low and high output states is as follows. VOL(min) = 0.4 volts, VOH(max) = 4.2 volts. The short circuit of output to high GND is 100 mA and short circuit current to VCC path at low output is 90 mA, The output frequency of bipolar pulses is, 50, 100, 1k, 10k and 20k Hz with 10μs dead band