Combined with HCS method and on-demand power control for single-phase DC/AC converter, the thesis will implement the control according to the requirements of the DSM program wh[r]
Trang 1MINISTRY OF EDUCATION
AND TRAINING
VIETNAM ACADEMY OF SCIENCE
AND TECHNOLOGY
GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
-
Nguyen Minh Cuong
IMPROVING THE EFFECT OF DEMAND-SIDE MANAGMENT PROGRAMS BY CONTROL METHODS FOR DISTRIBUTED
GENERATIONS
Major: Control and Automation Technology
Code: 9.52.02.16
SUMMARY OF ENGINEERING DOCTORAL DISSERTATION
Ha Noi - 2020
Trang 2This work is completed at:
Graduate University of Science and Technology Vietnam Academy of Science and Technology
Supervisor: Assoc.Prof.Dr Thai Quang Vinh
Reviewer 1: ……… Reviewer 2: ……… Reviewer 3: ……… This Dissertation will be officially presented in front of the Doctoral
Dissertation Grading Committee, meeting at:
Graduate University of Science and Technology Vietnam Academy of Science and Technology
At ………… hrs …… day …… month…… year 2020
This Dissertation is available at:
1 Library of Graduate University of Science and Technology
2 National Library of Vietnam
Trang 3INTRODUCTIONS
1 Introduction: DSM (Demand-Side Management) has been done by many
domestic and foreign researchers, but there is still no research to fully solve the PVG and WG exploitation system with conditions reality in Vietnam Currently, the problem of exploiting the maximum energy from these two sources has not been solved in the same system Therefore, the author chose the research topic
"Improving the effect of demand-side managment programs by control methods for distributed generations" to complete the issues that are still open
or have not been fully paid attention mentioned above
2 Thesis objectives and tasks: Develop a strategy for the DSM program to
operate the PVG and WG exploitation system in EPS Vietnam; develop the concept maps to meet the requirements of the DSM program
3 Object and scope of the study
- Subject of study: PVG and WG system structures in single-phase distributed power network have enough data on the forecasting of load graphs and input parameters in a certain future period This grid has the participation of the ES power store as a balance of capacity between sources and loads
- Scope of study: PVG panels are uniform and wind speed is the same at all positions on turbine blades; does not consider the type and charging capacity of the Energy Storage (ES - Energy Storage) as well as the ES control
4 The research focus of the thesis
- Develop operational strategies for DSM program in PVG, WG, ES and grid operation systems to meet load requirements These strategies are specifically tailored to EPS Vietnam, thereby ensuring the requirement to only buy electricity from EPS during off-peak hours
- Build controllers to meet the requirements of the DSM program The controller helps to maximize the power from PVG and WG under all operating conditions, the controller is meshed to meet the power requirements
5 Research Methodology: Analyzing the theory of the DSM program, the
Vietnamese EPS requirements and the characteristics of each source Develop set strategies for the whole system, controllers for converters to fulfill the requirements
of the DSM program and test simulation Building an experimental model to verify maximum capacity exploitation at MPP for PVG and the problem of natural or on-demand capacity allocation
6 The scientific and practical significance of the topic
- The scientific meaning of the topic is to build the exploitation model of PVG and WG operating according to the requirements of the DSM program in EPS Vietnam At the same time, building the concept maps to meet the requirements of the proposed DSM program
- The practical meaning of the topic is to propose an operating method to bring energy efficiency, help change the capacity flow in the whole system, limit the amount
of electricity to buy from EPS for the system to exploit the source system with the
participation of large-capacity ES and offers experimental installation experience
Trang 4Chapter 1 OVERVIEW OF COMPLEX RESOURCES AND PROGRAMS
ENERGY DEMAND MANAGEMENT 1.1 Overview of solar and wind power sources
1.2 DSM issue in the world and in Vietnam
1.3 The structure of the source system is operating under the DSM program
1.4 Existing problems and proposing solutions
1.4.1 Some problems still exist
• The problem of operating the source system according to the DSM model DSM model is applied through energy management and control programs at each node with the participation of many elements or for the entire EPS The overall goal of these programs is to plan the optimal operation of each element in each EPS
or between EPS, thereby achieving a goal function of minimizing the cost of purchasing power from the grid or minimizing the amount of power used grid verbs in consideration time Another expression of this program that is often mentioned recently is EH (energy hub) However, the EH model focuses on many different types of sources at a node and remains mainly theoretical problems These programs are combined with a weather forecasting system specialized in renewable energy exploitation, communication systems and operator dispatching specialists, thereby helping to operate the EPS in semi-isolated mode
In Vietnam, a three-price electricity model has long been proposed to encourage load households to consume electricity during off-peak hours and limit peak consumption However, electricity consumers in Vietnam have not really paid attention to this, especially consumer electricity consumers This has made it difficult for the dispatching of the whole system, causing transmission overload during peak hours
On the other hand, the incentive to install the power system at each load node (can be regarded as each power consumption location in the EPS) at the low voltage level is being raised, making the power flow throughout the EPS not as expected and also makes it difficult for the dispatching of the whole system The reason for this is that the power emitted from PVG is only available during the time there is solar radiation and the power emitted from WG is always abnormal This has made
it extremely difficult to mobilize additional resources for the power shortages relative to load At the same time, keeping power balance on the grid is also difficult, making the power at the nodes and frequencies in the whole system easy
to lose control This shows the role of the energy management program implementation at each load node with the participation of the source system At the same time, studies in the world and in Vietnam on the source system DSM have not considered the application of a large capacity ES capable of discharging/charging to meet the unstable characteristics of nature and love load
• Source control problem:
With PVG, the commonly used control method is to combine a MPP max power point monitoring technique in the MPPT max power point monitor with a
Trang 5control technique such as voltage control technique AVC average, SMC slip control technique, FL fuzzy control technique, control technique using ANN neural network The techniques of finding MPP are also quite many, diverse and according
to many different goals such as CV constant voltage, P&O disturbance and observation, INC inductance increase, Temp temperature, OG slope optimization, detection ESC extreme, Each technique has its advantages and disadvantages and can be assessed in terms of cost of investment, ease of use/ease of use, accuracy, and energy loss Most recently, IB detection and splitting technique has been proposed
to be used based on PVG's full mathematical model but only used as a single source for the 3-phase grid; Only the IB-AVC method can be built with taking the signal of the current on the inductor and the voltage at the input of the DC/DC converter to act as control signals The implementation of this control structure is complicated because two measurement variables have to be used
WG can be controlled via an active rectifier or through two converters, in which the active rectifier or DC/DC converter acts as a regulator of the power consumption corresponding to the maximum amount of capacity at a time With
WG, the extraction method is quite similar to PVG when there is a combination
of MPP searching technique with control technique However, there are only a few techniques for finding MPP commonly used with WG such as HCS hill climb, TSR pitch ratio, PSF power signal feedback Of these techniques, the HCS technique is most commonly used due to its ease of implementation under practical operating conditions
At the node with the participation of the power system, the DC/AC converter is controlled to perform the role of power flow regulation and grid coupling Single-phase DC/AC converter control is often studied in two main directions The first direction studies the grid-connected current control to regulate the DC voltage maintained at a fixed value when there is no energy-balancing element such as the power warehouse on the DC side
The second direction studies the power current control on the AC side in systems that have a constant voltage holding element on the DC side In particular, the control of the power current flowing through the DC/AC voltage fluctuation according to the preset values has been researched recently The determination of the parameters of controllers should be made clear when applicable to DSM programs
• Determining the optimal ES capacity: currently there are several methods
of determining the optimal capacity for the ES to be able to respond to different problems The research direction to evaluate the ratio of lack of power (RLP) is based on the assessment of the ratio of the total capacity shortage due to the source not meeting the load and the total load capacity The optimum ES power
is then determined as the value that ES can compensate for the load so that RLP reaches the required RLP value It can be seen that this method can use past or future data on the load and source system parameters to give the optimal value
of the ES capacity When RLP = 0, the load is fully powered by the ES However, this method cannot evaluate the time of purchasing power, that is, it cannot
Trang 6evaluate the effect of electricity price on the determination of ES capacity The research direction uses the quantity of the probability of a power failure at any one time in the whole considering cycle The value of this probability varies from time to time and is applied to achieve the minimum cost function goal caused by
a power outage or to reach LSLP It can be seen that this research also gives an assessment of the power supply capacity and has not yet evaluated the impact of the electricity price on the capacity of the ES Direction of research and assessment of required energy of the load or requirement of energy storage of the source system By specifying the storage time taking into account redundancy over a certain period of time, the capacity of the ES is considered to
be able to guarantee the power supply to the load throughout the consideration cycle However, the capacity determined by this method is quite large and cannot evaluate the interaction between the source system and the power system as well
as the effect of the electricity price on the capacity of the ES
1.4.2 Propose a solution
Most studies on PVG and WG are still single or combined studies based
on traditional methods with low energy efficiency Therefore, the thesis proposes the following solutions:
• Develop a DSM program at the load node with the participation of the source system in actual conditions in Vietnam and with the participation of a large-capacity ES: this program will be based on the regulation of 3 electricity prices for secondary households load and regulations on electricity prices of households to load for EPS when exploited from source to EPS in Vietnam The thesis will propose operational strategies for the DSM program to plan the whole system's operation on the basis of requirements management of loads and generation capacity from sources, storage capacity of ES The DSM program helps to regulate the flow of capacity throughout the system and determine the optimal capacity for the ES that meets the EPS requirements in Vietnam
• Construction of control structure according to IB-AVC method for PVG object using PID controller with the use of a single measuring signal which is the voltage at the input of the DC/DC converter This will also be the method of maximizing power from PVG under all operating conditions because it is always possible to determine the parameters that need to be controlled before controlling Combined with HCS method and on-demand power control for single-phase DC/AC converter, the thesis will implement the control according
to the requirements of the DSM program while ensuring maximum exploitation
of the capacity of the source system
• Construction of a control structure for single-phase DC/AC converter, which uses a resonant controller to overcome the disadvantages of a conventional PI controller
1.5 Conclusions of chapter 1
Trang 7Chapter 2 DESCRIPTION OF RESOURCES MATHEMATICS AND DSM
MATHEMATICS 2.1 Solar battery source
2.2 Wind power
2.3 Develop a DSM program at the node to exploit the source system
in specific conditions of the Vietnamese electricity system
2.3.1 The strategy of power flow regulation according to DSM model 2.3.2 Some constraints and limitations
• Predictive curves are reallocated to rectangular plots
• The ith step of the divided variables corresponds to the timelines
• All power quantities in the entire system are converted to DCbus
The total power of the predictive power system obtained at DCbus at step
i is determined by (2.29):
Gconv PVGconv WGconv
P (i) = P (i) + P (i) (2.29) The total amount of power that can be obtained from the DCbus on the DCbus at H, M, L hours in the cycle is determined by (2.30), (2.31), (2.32):
GconvM 3
E
Total required energy of the load in hours H, L, M in cycle is determined
by (2.33), (2.34), (2.35):
loadM 3
E
Trang 8
The total energy generated of the EGconv source system and the required power of the load Eload over the duration of the consideration cycle are determined by (2.36) and (2.37):
Gconv GconvH GconvM GconvL
load loadH loadM loadL
2.3.3 Proposing DSM algorithm to operate at nodes with the participation of the source system in specific conditions of the Vietnamese power system
Figure 2.8 DSM algorithm for systems that exploit source systems
The following algorithms will not repeat the input data blocks because they are both serialized algorithm in Figure 2.8 or serial of each other
Trang 9Figure 2.9 System-wide operating algorithm for DSM mode 1
Trang 10Figure 2.10 Algorithm for the whole system of hours L1 of the scheme DSM1
With: Ede is the lack of electricity,
EsL1 is the excess amount of electrical energy in the source system
in the hour L1,
Es(i) is instantaneous excess power