scholarly journals Energy and Exergy Evaluations of a Combined Heat and Power System with a High Back-Pressure Turbine under Full Operating Conditions

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4484 ◽  
Author(s):  
Shifei Zhao ◽  
Weishu Wang ◽  
Zhihua Ge
Keyword(s):  
Power Systems ◽  
Power System ◽  
Evaluation Method ◽  
Waste Heat ◽  
Combined Heat And Power ◽  
Back Pressure ◽  
Operating Conditions ◽  
Pressure System ◽  
Heating Capacity ◽  
Energy And Exergy

High back-pressure technology is a promising method for the waste heat recovery of exhaust steams in combined heat and power systems. In this research, a 300 MW coal-fired subcritical combined heat and power system was selected as the reference system, and modeled in EBSILON professional. Then, energy-based and exergy-based performances of the high back-pressure system and traditional combined heat and power system were compared under full operating conditions. Moreover, a novel exergy-based evaluation method, which considers the energy level of the heating supply, was proposed and applied to evaluate the two systems. Results show that: In design conditions, both the heating capacity and power output of the high back-pressure system were higher than those of the extraction condensing system, which led to 17.67% and 33.21% increments of the gross thermal efficiency and generation efficiency, respectively. Compared with the extraction condensing system, the exergy efficiencies of the high back-pressure system were 7.04–8.21% higher. According to the novel exergy-based evaluation, the exergy efficiencies for the generation of the high back-pressure system and extraction condensing system were 46.48% and 41.22%, respectively. This paper provides references for the thermodynamic performance evaluation of the combined heat and power system.

scholarly journals Modified High Back-Pressure Heating System Integrated with Raw Coal Pre-Drying in Combined Heat and Power Unit

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2487 ◽  
Author(s):  
Heng Chen ◽  
Zhen Qi ◽  
Qiao Chen ◽  
Yunyun Wu ◽  
Gang Xu ◽  
...  
Keyword(s):  
Power Generation ◽  
Flue Gas ◽  
Waste Heat ◽  
Heating System ◽  
Combined Heat And Power ◽  
Back Pressure ◽  
Coal Consumption ◽  
Heating Capacity ◽  
Boiler Efficiency ◽  
Saving Effect

A conceptual high-back pressure (HBP) heating system cooperating raw coal pre-drying for combined heat and power (CHP) was proposed to improve the performance of the HBP-CHP unit. In the new design, besides of heating the supply-water of the heating network, a portion of the exhaust steam from the turbine is employed to desiccate the raw coal prior to the coal pulverizer, which further recovers the waste heat of the exhaust steam and contributes to raising the overall efficiency of the unit. Thermodynamic and economic analyzes were conducted based on a typical 300 MW coal-fired HBP-CHP unit with the application of the modified configuration. The results showed that the power generation thermal efficiency promotion of the unit reaches 1.7% (absolute value) owing to suggested retrofitting, and meanwhile, the power generation standard coal consumption rate is diminished by 5.8 g/kWh. Due to the raw coal pre-drying, the energy loss of the exhaust flue gas of the boiler is reduced by 19.1% and the boiler efficiency increases from 92.7% to 95.4%. The impacts of the water content of the dried coal and the unit heating capacity on the energy-saving effect of the new concept were also examined.

scholarly journals Cascade Utilization of Flue Gas Waste Heat in Combined Heat and Power System with high Back-pressure (CHP-HBP)

2016 ◽  
Vol 104 ◽  
pp. 27-31 ◽  
Author(s):  
Shifei Zhao ◽  
Xiaoze Du ◽  
Zhihua Ge ◽  
Yongping Yang
Keyword(s):  
Power System ◽  
Flue Gas ◽  
Waste Heat ◽  
Combined Heat And Power ◽  
Back Pressure

Slow flow solutions and stability analysis of single machine to infinite bus power systems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
M. G. Suresh Kumar ◽  
C. A. Babu
Keyword(s):  
Power Systems ◽  
Power System ◽  
Single Machine ◽  
Multiple Scales ◽  
Operating Conditions ◽  
Phase Portraits ◽  
Slow Flow ◽  
Approximate Analytical Expression ◽  
Flow Equations ◽  
Load Angle

Abstract Nonlinearity is a major constraint in analysing and controlling power systems. The behaviour of the nonlinear systems will vary drastically with changing operating conditions. Hence a detailed study of the response of the power system with nonlinearities is necessary especially at frequencies closer to natural resonant frequencies of machines where the system may jump into the chaos. This paper attempt such a study of a single machine to infinite bus power system by modelling it as a Duffing equation with softening spring. Using the method of multiple scales, an approximate analytical expression which describes the variation of load angle is derived. The phase portraits generated from the slow flow equations, closer to the jump, display two stable equilibria (centers) and an unstable fixed point (saddle). From the analysis, it is observed that even for a combination of parameters for which the system exhibits jump resonance, the system will remain stable if the variation of load angle is within a bounded region.

scholarly journals Research and Application of New Condensing Extraction Backpressure heating technology of 330 MW unit

2020 ◽  
Vol 143 ◽  
pp. 02047
Author(s):  
Shufang Tang ◽  
Guoan Tang ◽  
Xiaohong He ◽  
Lijun Zheng ◽  
Cong Yu ◽  
...  
Keyword(s):  
Power System ◽  
Economic Benefit ◽  
Peak Load ◽  
Combined Heat And Power ◽  
Heating Capacity ◽  
Load Regulation ◽  
Generation Power ◽  
Heating Technology

This paper introduces the retrofit scheme of the New Condensing Extraction Backpressure heating technology, and the technology is recommend for use by comparing and analysing the combined heat and power system based on a 330MW unit retrofit. After improvement, the heating capacity has been Obvious improved, the generation power has been greatly reduced and the capacity of peak load regulation has been significantly improved, which can not only realize the thermoelectric decoupling, but also obtain the remarkable economic benefit.

scholarly journals Flexibility Evaluation Method of Power Systems with High Proportion Renewable Energy Based on Typical Operation Scenarios

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 627
Author(s):  
Xiangying Tang ◽  
Yan Hu ◽  
Zhanpeng Chen ◽  
Guangzeng You
Keyword(s):  
Renewable Energy ◽  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Supply And Demand ◽  
Flow Distribution ◽  
Occurrence Probability ◽  
Flexible Operation

The development of renewable energy represented by wind, photovoltaic and hydropower has increased the uncertainty of power systems. In order to ensure the flexible operation of power systems with a high proportion of renewable energy, it is necessary to establish a multi-scenario power system flexibility evaluation method. First, this study uses a modified k-means algorithm to cluster operating scenarios of renewable energy and load to obtain several typical scenarios. Then, flexibility evaluation indices are proposed from three perspectives, including supply and demand balance of the zone, power flow distribution of the zone and transmission capacity between zones. Next, to calculate the flexibility evaluation indices of each scenario—and according to the occurrence probability of each scenario—we multiplied the indices of each scenario by the scenario occurrence probability to obtain comprehensive evaluation indices of all scenarios. Based on the actual historical output data of renewable energy and load of a southern power system in China, a flexibility evaluation was performed on the modified IEEE 14 system and modified IEEE 39 system. The results show that the proposed clustering method and flexibility indices can effectively reflect the flexibility status of the power system.

scholarly journals An approach for a multi-stage under-frequency based load shedding scheme for a power system network

2020 ◽  
Vol 10 (6) ◽  
pp. 6071
Author(s):  
Mkhululi Elvis Siyanda Mnguni ◽  
Yohan Darcy Mfoumboulou
Keyword(s):  
Decision Making ◽  
Power Systems ◽  
Power System ◽  
New England ◽  
Operating Conditions ◽  
Load Shedding ◽  
Power Network ◽  
Load Demand ◽  
Multi Stage ◽  
System Frequency

The integration of load shedding schemes with mainstream protection in power system networks is vital. The traditional power system network incorporates different protection schemes to protect its components. Once the power network reaches its maximum limits, and the load demand continue to increase the whole system will experience power system instability. The system frequency usually drops due to the loss of substantial generation creating imbalance. The best method to recover the system from instability is by introducing an under-frequency load shedding (UFLS) scheme in parallel with the protection schemes. This paper proposed a new UFLS scheme used in power systems and industry to maintain stability. Three case studies were implemented in this paper. Multi-stage decision-making algorithms load shedding in the environment of the DIgSILENT power factory platform is developed. The proposed algorithm speeds-up the operation of the UFLS scheme. The load shedding algorithm of the proposed scheme is implemented as a systematic process to achieve stability of the power network which is exposed to different operating conditions. The flexibility of the proposed scheme is validated with the modified IEEE 39-bus New England model. The application of the proposed novel UFLS schemes will contribute further to the development of new types of engineers.

scholarly journals Steady state stability in electrical power systems considering operation limits in generators, transformers and transmission lines

2021 ◽  
Vol 18 (2) ◽  
Author(s):  
Fredy Estuardo Tamayo Guzmán ◽  
Carlos Andrés Barrera-Singaña
Keyword(s):  
Steady State ◽  
Power Systems ◽  
Power System ◽  
Transmission Lines ◽  
Electrical Power ◽  
Operating Conditions ◽  
Electrical Power Systems ◽  
Capacity Curves ◽  
Remedial Actions ◽  
Steady State Stability

Electrical power systems are exposed to several events that can cause unstable operation scenarios. This is due to improper operation of certain components. If an event occurs, the system must be designed to overcome that contingency, thus remaining in a permanent condition that must be evaluated in order to monitor and prevent a possible collapse of the system. An evaluation of steady state stability is proposed at this work based on the capacity curves of generators, transformers and transmission lines. These remarked curves provide information on the operation point of these elements, thus allowing the application of remedial actions. PowerFactory and Matlab are used to carry out the tool for monitoring the operation points after a contingency. The effectiveness of the developed tool is validated at the IEEE 39-bus power system model, where results shows that the functionalaty for different contingencies based on the operating conditions when the components of the power system are varied, cosnquently, the tool identifies cases that require actions at the operational level.

scholarly journals Multicriteria Assessment of Combined Heat and Power Systems

2018 ◽  
Vol 10 (9) ◽  
pp. 3240 ◽  
Author(s):  
Santoso Wibowo ◽  
Srimannarayana Grandhi
Keyword(s):  
Power Systems ◽  
Power System ◽  
Combined Heat And Power ◽  
Assessment Model ◽  
Intuitionistic Fuzzy Numbers ◽  
Ideal Solutions ◽  
Multicriteria Assessment ◽  
Overall Performance ◽  
Power System Performance ◽  
Interval Valued

This paper presented a multicriteria assessment model for evaluating the performance of combined heat and power systems. Interval-valued intuitionistic fuzzy numbers were used for representing the subjective and imprecise assessments of the decision maker in evaluating the relative importance of the criteria, and the performance of individual combined heat and power systems. An effective algorithm was developed based on the concept of ideal solutions for calculating the overall performance index, for each combined heat and power system across all criteria. An example was presented to demonstrate the applicability of the multicriteria assessment model, for dealing with real world combined heat and power system performance evaluation problems.

Application of Moth Flame Optimization Algorithm for AGC of Multi-Area Interconnected Power Systems

2018 ◽  
Vol 7 (1) ◽  
pp. 22-49 ◽  
Author(s):  
Ajit Kumar Barisal ◽  
Deepak Kumar Lal
Keyword(s):  
Power Systems ◽  
Power System ◽  
Pid Controller ◽  
Thermal Power ◽  
Operating Conditions ◽  
System Model ◽  
Source Power ◽  
Interconnected Power Systems ◽  
Thermal Power System ◽  
Moth Flame Optimization Algorithm

A novel attempt has been made to use Moth Flame Optimization (MFO) algorithm to optimize PI/PID controller parameters for AGC of power system. Four different power systems are considered in the present article. Initially, a two area thermal power system is considered for simulation. The superiority of the proposed MFO optimized PI/PID controller has been demonstrated by comparing the results with recently published approaches such as conventional, GA, BFOA, DE, PSO, Hybrid BFOA-PSO, FA and GWO algorithm optimized PI/PID controller for the same power system model. Then, a sensitivity analysis is carried out to study the robustness of the system to wide changes in the operating conditions and system parameters from their nominal values. The proposed approach is extended to different realistic multi-area multi-source power systems with diverse sources of power generations for simulation study. The acceptability and efficacy of the proposed technique is demonstrated by comparing with other recently published techniques.

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