Inverter Air Conditioner Research Articles

Modeling and analysis of inverter air conditioners for primary frequency control considering signal delays and detection errors

The primary frequency control (PFC) is becoming more important for maintaining the system balance between the generation and consumption. The progressed intelligent home system has made it easier for household appliances to provide PFC services to power systems. Among the appliances, inverter air conditioners (IACs) can adjust the operating power rapidly by changing the compressor frequency and have little influence on the customer comfort. In this paper, an IAC model is developed considering the thermal model of the room, whose compressor operating frequency is determined by the system frequency deviation and the temperature deviation between the room and the set value. Two control methods for the aggregated IACs are proposed, the centralized detection control (CDC) method and the distributed detection control (DDC) method. The system frequency is detected by the control center in the CDC method, while the system frequency is monitored locally by each IAC controller in the DDC method. Generally, the CDC method can get more accurately frequency detection than the DDC method. However, the control center in the CDC method has to send control signals to each IAC in real time, which causes communication delays for the IACs to adjust the operating power. As for the large-scale aggregated IACs, the simulation results show that the signal delays in the CDC method have more negative effects than the detection errors in the DDC method.

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.

Techno-economic analysis of an air conditioning heat pump powered by photovoltaic panels and the grid

This work presents an environmental and techno-economic study of an inverter air conditioner simultaneously powered by photovoltaic panels and the grid, without batteries. The unit provides the thermal demand to an office in an administrative building located in Alicante (South East Spain).In comparison with other systems which also use renewable energy for air conditioning, this one presents significant advantages. It is comparatively simple, reliable, has low maintenance needs and its renewable energy production is entirely self-consumed, which avoids problematic interaction with the grid.The system has been monitored during one year to measure the thermal energy provided to the room, the electrical consumption of the device and the photovoltaic and grid contribution to it.Experimental results of some Key Performance Indicators are presented as a result of a one year data collection campaign. The measurements show a solar contribution of 54% to the electricity consumed by the system. As a result, the ratio between the thermal energy and grid electricity consumption during one year is SPFsys = 9.6. Consequently, the primary non–renewable energy consumption is drastically reduced to a 26% of the reference system (SPFref=2.5).Furthermore, the techno-economic study concludes that in spite of requiring a higher initial investment in the system, the saving produced by the lower electricity consumption, results in an annualized cost of 84% of the reference system cost.

A quantity-quality-based optimization method for indoor thermal environment design

This paper proposes a quantity-quality-based optimization method of indoor thermal environment design that emphasizes entransy and exergy analysis. We scrutinized the different focuses of entransy and exergy in examining an energy-related phenomenon or process, and pointed out the need for integrating entransy and exergy for the optimization of indoor thermal environment design. The proposed method contributes to identifying the most energy-efficient solution for attaining the same level of indoor thermal comfort for end users by quantifying the entransy and exergy efficiency of active technologies. With this method, a benchmark technical solution was properly determined and benchmarks for entransy dissipation and exergy loss during the process of thermal environment design were quantified. Entransy dissipation and exergy loss under common technologies were compared with the benchmark values. The concepts of relative entransy savings and relative exergy savings were defined as the evaluation indexes of technical energy efficiency. Referencing winter indoor thermal environment design for residential buildings in hot-summer and cold-winter (HSCW) regions in China, the proposed method was applied to assess the energy efficiency of different heating methods, including an inverter air conditioner, an “air source heat pump + floor radiation,” a “wall-hanging gas heater + floor radiation,” a “wall-hanging gas heater + radiator,” and an oil-filled radiator. This paper recommended that the “air source heat pump + floor radiation” be used for residential buildings in winter in HSCW regions to improve energy efficiency. In addition, the optimization results of the proposed method were compared with that of traditional energy and exergy analysis methods. The results showed that the new method more accurately analyzed the energy flow in indoor thermal environment design, and therefore can serve as an improved way of thinking about follow-up studies on the optimization of heat pump units and the operation strategies of floor radiant heating systems.

Demand Response From the Control of Aggregated Inverter Air Conditioners

Inverter air conditioners (ACs) account for a large proportion of air conditioning loads in many countries and, thus, contribute significantly to the peak loads in these areas, especially in summer. On the other hand, as an important category of thermostatically controlled load with thermal energy storage capability, inverter ACs also have the potential to provide considerable flexibility for electric power systems that are faced with increasing challenges posed by high penetration of renewable power generation. This paper focuses on the demand response from the control of the aggregated inverter ACs for load reduction. A virtual energy storage system (VESS) model that encapsulates the room with an inverter AC was established based on the electric model of an inverter AC and the thermodynamic model of a room. Based on the VESS model, a virtual state of charge (VSOC) priority-based load reduction control method with temperature holding and linear recovery strategies was proposed. The VSOC priority based control was designed to decrease the negative impact of load reduction on customers’ thermal comfort from the perspective of the whole AC population. The temperature holding strategy was designed to reduce the electric power of an AC while ensuring that the indoor temperature is always below the allowable limit. The linear recover strategy was proposed to reduce the load rebound after load reduction. Four cases were studied regarding the operation and load reduction of the 100 inverter ACs, and the simulation results verified the models established and the effectiveness and advantages of the proposed load reduction control method.

Data-Driven Reserve Allocation With Frequency Security Constraint Considering Inverter Air Conditioners

Inverter air conditioners (IACs) with considerable total capacity and fast response speed are ideal demand response resources, which are of significant potential to provide reserve capacity for the power system frequency regulation. However, due to the complexity and implicitness of the frequency response models, it is difficult to formulate the optimization problem considering frequency dynamics to allocate reserve capacity precisely. In this paper, a data-driven method is proposed for reserve allocation with the frequency security constraint considering IACs. Firstly, the equivalent frequency response model of aggregated IACs is developed considering electrical-thermal characteristics and then incorporated into the frequency regulation framework of power systems along with conventional generators. Then, simulations are implemented to generate massive reserve samples with deterministic frequency security labels. Later, a support vector machine (SVM) based frequency security classifier is trained to convert the implicit frequency security constraint into polynomials and reshape the reserve allocation problem into a solvable general quadratically constrained quadratic program (QCQP). Finally, a heuristic Suggest-and-Improve (SI) method is adopted to deal with the nonconvex QCQP of interest. It is demonstrated by numerical studies that the proposed data-driven method enables power systems to operate closer to the frequency security boundaries and thus achieve lower costs.

Thermal management solution for enclosed controller used in inverter air conditioner based on heat pipe heat sink

Enclosing the controller in an inverter air conditioner can prevent the damage from insects and dusts in the ambience, but may decrease the efficiency of heat dissipation. The objective of this study is to propose a novel thermal management solution based on the heat pipe heat sink (HPHS) for cooling the enclosed controller. The heat flux of the chips in the controller is transferred to a HPHS by the forced convection supplied by an internal micro fan and then dissipated to the ambience. Two types of HPHSs (i.e. U-type and L-type) are designed, and the location of micro fan is optimized. The application of the proposed solution in a real inverter air conditioner shows that, the thermal management employing L-type HPHS is the better one and can reduce the average temperatures of small-power chips and large-power chips by 10.0 °C and 5.9 °C, respectively.

Design of Room Temperature Control System for Inverter Air Conditioner Based on Fuzzy Neural Network

With the progress of science and technology and the demand of people for material life, smart home appliances have become an inevitable trend of the development of household appliances in the future. In the face of widely used inverter air conditioner and its fast temperature regulation demand for closed indoor environment, the design of fuzzy neural network controller with inverter air conditioner is designed on the basis of setting up the transfer function model of indoor temperature and environment, which is compared with traditional PID and its fuzzy control by simulation and verification. The speed and stability of adjusting the temperature of closed indoor rooms have achieved better results.

Energy storage modeling of inverter air conditioning for output optimizing of wind generation in the electricity market

In order to achieve the compatibility of the air conditioning (AC) loads with the current dispatch models, this paper utilizes demand response (DR) technology as energy storage resources to optimize the aggregator's behaviors in the real-time market for less economic loss caused by the fluctuations of wind power. The inverter AC, as a typical demand response resource, is constructed as a power type battery model (PTBM) and a capacity type battery model (CTBM) according to the different control methods, which are expressed through a circuit model and mathematical model to describe the energy storage characteristics of ACs. Moreover, the comparisons between the PTBM and CTBM are given analytically by their response speed, power &energy capacity and the cost of control, which will be helpful to guide the associated operators to choose the appropriate models to take part in demand response. Considering that the wind generation fluctuates frequently and greatly, the PTBM is chosen to take part of the demand response for output optimizing of the wind generation. The simulation results demonstrate that PTBMs can work in the way of conventional batteries (CBs) to optimize wind generation in the real-time market.

Consensus control strategy of an inverter air conditioning group for renewable energy integration based on the demand response

In order to improve the degree of renewable energy integration, the demand response resource, especially on the air conditioning load side, has received attention. Currently, most of the control modes for air conditioners are centralised control, which is difficult to be applied to widely distributed air conditioning. The current studies focus on central air conditioning, but there are few studies on split-type inverter air conditioning, even though inverter air conditioning has become the most common split air system on the market. With this background, this study designs a consensus control strategy on the basis of distributed control mode, which for inverter air conditioners. The strategy is used for renewable energy integration in the studied region. The test results of various cases reveal the following findings: (i) the strategy adapts to the widely distributed air conditioning, (ii) the strategy can guarantee a fair allocation of power imbalance and user comfort, (iii) the control strategy can adapt to the uncertainties of air conditioners and the urban microclimate while efficiently consuming renewable energy. Therefore, the proposed consensus control strategy has practical value.

Price-responsive model-based optimal demand response control of inverter air conditioners using genetic algorithm

The rapid developments of advanced metering infrastructure and dynamic electricity pricing provide great opportunities for residential electrical appliances, especially air conditioners (ACs), to participate in demand response (DR) programs to reduce peak power consumptions and electricity bills. One of the biggest challenges faced by residential DR participants is the lack of intelligent DR control methods which enable residential ACs to automatically respond to dynamic electricity prices. Most existing studies on DR control of residential ACs focus on single-speed ACs. However, inverter ACs which have higher part-load efficiencies have been extensively installed in today’s residential buildings. This paper presents a novel model-based DR control method for residential inverter ACs to automatically and optimally respond to day-ahead electricity prices. A control-oriented room thermal model and steady-state model of inverter ACs are developed and integrated to predict the coupled thermal response of the room and AC for the purpose of model-based control. Optimal scheduling of indoor air temperature set-points is formulated as a nonlinear programming problem which seeks the preferred trade-offs among electricity costs, thermal comfort and peak power reductions. Genetic algorithm (GA) is used to search the optimal solution of the nonlinear programming problem. Simulation results show that compared with the baseline case, the proposed model-based optimal control method can reduce the whole electricity costs and the peak power demands during DR hours while meeting thermal comfort constraints. Besides, sensitivity analyses on the trade-off weightings in the optimization objective function demonstrate that electricity costs, occupant comfort and peak power reductions are sensitive to the weightings and the use of the weightings is effective in achieving the best trade-off.

Retracted: Setup and operational cost analysis of 1 Horse power rated split unit inverter and non inverter air conditioner for home usage in Malaysia

Inverter type air conditioner that has been introduced in Malaysian market in recent years, giving an option between the new technology and previous technology which is non-inverter type air conditioner. However, unit price different between them sometime become an obstacle in order to opted for the latest technology. In this article, setup and operational cost analysis has been done with 10 models of 1 horse power rated air conditioners, 7 of them are inverter type air conditioner while only 3 of them are non-inverter type air conditioner. Comparison between inverter and non-inverter type air conditioner has been done with 3 brands of air conditioner. Break-even points for all three brands are less than 1.5 years. In addition, comparison between 7 models of inverter type and 3 model of non-inverter type air conditioner to find out which model is more economical in their segment has been done.

Performance Optimization and Development of an Efficient Solar Photovoltaic Based Inverter Air Conditioning System

Presently, Inverter Air Conditioners are becoming popular due to their several advantages. This technology results in consuming less amount of energy for achieving weatherization and has potential to be easily powered by economical energy systems. Few correlated research have been carried out in this field but the outcomes are not significant due to system cost. In this work, the proposed Solar Photovoltaic based Inverter Air Conditioning system using DC motor was designed, modeled and tested for the weather conditions of Aligarh-India. Based on the simulation results, this work formulates an optimization problem depending on the general weather conditions and the time of operation, in order to reduce the operating cost. Optimized design specifications are outlined and verified for onsite implementation.

Performance Comparison of Solar Assisted and Inverter Air-Conditioning Systems in Malaysia

© 2017, University of Malaya. All rights reserved. Heating, ventilation, and air-conditioning (HVAC) systems account for approximately 55% o f the total energy consumption in buildings. Different types of cooling technologies that integrate solar thermal energy have been explored because of increasing worldwide energy shortage. Latest air-conditioning systems have achieved improved energy efficiency. The application o f solar energy to various types of HVAC systems proved its huge potential for reducing energy usage. However, solar radiation is highly time dependent and fails to meet building demand. In this study, the potential of a 1.5 HP solar assisted air-conditioning system was evaluated by collecting and using real data, including current, voltage, power, and temperature. The application o f the solar-assisted and inverter-type air-conditioning systems was compared for evaluating their performances. The study was conducted in the northern region of Malaysia, specifically Kedah, in a room with the same as that o f a standard office space. Results showed that the average coefficients o f performance of the solar assisted air-conditioning system ranged from 3.00 to 4.45. This range allows for the optimal consumption of electric energy without wastage. Therefore, the solar-assisted air-conditioning system can provide an environmentally friendly alternative to reducing electricity rates.

暖房時を対象とするユーザー指向の住宅用エアコンエネルギー消費量の推定法に関する研究 : 第2報-CFDモデルの組込みによるインバータエアコン暖房の考察

暖房時を対象とするユーザー指向の住宅用エアコンエネルギー消費量の推定法に関する研究 : 第2報-CFDモデルの組込みによるインバータエアコン暖房の考察

Performance analysis of wind catcher integrated with shower cooling system to meet thermal comfort conditions in buildings

In this study, natural ventilation and cooling of a two-floor building connected to a wind catcher were studied in which a shower cooling system has been used to reduce ambient air temperature. The capability of the system to meet thermal comfort conditions based on adaptive thermal comfort and ISO/EN 7730 standards was evaluated under different operating conditions. In order to estimate the air change per hour and air flow simulation around and inside the test building, ANSYS FLUENT 6.3 software was utilized and the air temperature at the outlet of the shower cooling system was computed using a thermodynamic model. The results showed that for the wind velocity beyond 0.4 m/s, the ACH value for the rooms could be set in the range of 3–20 h−1 with the regulation of window's aperture. Under this condition, the temperature and relative humidity of air stream into the building did not change with the wind velocity. Also, it was found that when three buildings are situated in one direction, ACH value for the middle building is less than others. As the ACH value increases, thermal comfort conditions are met for larger values of required cooling demands. Although electrical energy consumption of the proposed system is already lower than evaporative air coolers, it cannot compete with split inverter air conditioners where the relative humidity of ambient air is high.

Passive solar cooling of single-storey buildings by an adsorption chiller system combined with a solar chimney

This study proposes a new solar system for passive cooling of buildings. The system is composed of a solar driven adsorption chiller, a solar chimney and a cooling channel. The system is simulated theoretically and the room temperature, relative humidity and air change per hour (ACH) are evaluated. In addition, the effects of different parameters including the ambient conditions, cooling demand of the room, dimensions of the solar chimney and the cooling channel on room temperature and ACH are studied. The results show that the system is able to provide the required ACH and keep the indoor temperature within the thermal comfort limits in both arid and humid climates. It is found that ACH remains almost constant during the system's operation time at each cooling demand. It is also indicated that adoption of three cooling plates in the channel provides the lowest room temperature, and use of three plates instead of one reduces room temperature by 26.8%. Moreover, it is found that the proposed system consumes about 37% less electric energy in comparison with a split inverter air conditioner of the same cooling power.

Review of the Capacity Control Capability of Commercial Air Conditioner Units with Variable Speed Compressor

The scope of the specific study is the extraction of mathematical relations which correlate the nominal capacity with capacity range of an inverter air conditioner unit with variable speed compressor under standard conditions, that is, measurements of minimum and maximum power of air conditioner under specific indoor and outdoor temperatures. Initially, the necessary statistical information for nominal minimum and maximum capacity will be collected from a sample of 544 different inverter air conditioner models. Furthermore, the regression analysis and the change curves of capacity range with regard to the nominal capacity for cooling and heating operation will be drawn. Also the change of turndown ratio with regard to the nominal capacity and capacity range of air conditioners will be studied. The conclusion that arises is that the maximum capacity and capacity range are varied linearly for cooling and heating operation. There is no clear indication for turndown ratio due to low correlation coefficient of the mathematical model.

Study of Reactive Flow of Split-type Air Conditioners and Inverter Air Conditioners in the Consumer Units and the Public Electricity Companies

Study of Reactive Flow of Split-type Air Conditioners and Inverter Air Conditioners in the Consumer Units and the Public Electricity Companies

A Simulation Study of Inverter Air Conditioner Controlled to Supply Reactive Power

Recently, inverter has been applied in air conditioning technologies. Besides energy saving capability, inverter can also control reactive power by using the dq-axis theory. It separates current into two parts that enable decoupled control of active power and reactive power. This presents a simulation study of an inverter air conditioner controlled to supply reactive power for the installation area without sacrificing thermal comfort. Power factor improvement can reduce loss in transformer and line so power that be saved can be used for others load. Simulation results carried out by MATLAB/SIMULINK showed that reactive power controllability depends on variation of the indoor and outdoor temperature and rated current of equipment.