Nghiên cứu cơ sở khoa học nâng cao hiệu quả vận hành phát điện các hồ chứa bậc thang trong thị trường điện cạnh tranh, áp dụng cho lưu vực sông chu tt tiếng anh

MINISTRY OF EDUCATION

MINISTRY OF AGRICALTURE

AND TRAINING

RURAL DEVELOPMENT

THUY LOI UNIVERSITY

LE QUOC HUNG

RESEARCH ON THE SCIENTIFIC BASIS TO IMPROVE
THE EFFICIENCY OF ELECTRICITY GENERATION FOR
CASCADE RESERVOIRS IN COMPETITIVE POWER
GENERATION MARKET, APPLIED FOR THE CHU RIVER BASIN

Specialty: Hydraulic Engineering
Code: 9580202

DISSERTATION ABSTRACT

HANOI, 2019


This dissertation is completed at Thuyloi University

Advisor 1: Assoc. Prof. Dr. Phan Ky Nam
Advisor 2: Assoc. Prof. Dr. Le Van Nghi

Reviewer 1: Prof. Dr. Ha Van Khoi – Vietnam Water Resources Development

Association
Reviewer 2: Assoc. Prof. Dr. Nguyen Danh Oanh – Institute of Energy
Reviewer 3: Assoc. Prof. Dr. Do Van Chieu – National University of Civil
Engineering

This dissertation will be presented to the Evaluation Committee of Thuyloi
University, Hanoi at 13:30 on 11 March 2019.

This dissertation will be filed in following libraries:
- National Library.
- Thuyloi University Library.


INTRODUCTION

1.

Statement of the problem

In recent years, hydropower has been developing strongly in our country and is
constantly increasing in the following years. Apart from the development of power
sources from wind, coal, solar energy, gas, etc., it is necessary to study and exploit
effectively the constructed hydropower plants (HPPs) to reduce the difficulty of
supplying electricity for production. Along with that, the process of reservoir operation,
flood discharge of reservoirs to optimize the operation of the reservoirs to ensure the
harmony of the benefits of water use and the maximum use of hydropower, flood and
drought mitigation at the downstream is a matter of social concern and is always
current. At present, the Government has issued a joint operating procedure for all
reservoir system in Vietnam's large basins, including the Ma River basin. However,
reservoir system operating, especially in the dry season, only regulates safe operation

and minimum flow for downstream areas, but not to mention operational efficiency and
competitive entry into the electricity market. With the practical requirements as stated,
the topic of "Research on the scientific basis to improve the efficiency of electricity
generation for staged reservoirs in competitive power generation market, applied for the
Chu River basin " is extremely necessary to meet the current practical requirements in
Vietnam.
2.

Objective of the study

To study the scientific basis to build the optimal calculation model of electricity sales
for the system of staged reservoirs under competitive power generation conditions in
order to provide operational instructions in combination with the coordination chart
deliver the full annual output contract and drive to the largest revenue.
1


To analyze and build the relationship between the decrease and the distribution of the
hourly electricity price, according to the accumulated time of each month with the
monthly electricity output and the number of monthly trading hours, then to calculate
annual adjustment to improve the efficiency of electricity generation, bringing the
biggest revenue to the investors.
3.

Subject and scopes of the study

Objectives of the study: The research subject of the project is a system of reservoirs
regulating the combined electricity generation in the Chu River basin in the context of
competitive power generation in Vietnam.
Scope of the study: The scope of applied research is to improve the efficiency of the

operation of the Hua Na and Cua Dat reservoirs combined with electricity generation in
competitive power generation conditions in Vietnam.
4.

Study methodology

(1) Inherited method; (2) Mathematical simulation method; (3) Analytical methods.
5.

Scientific and practical contributions

(1) The dissertation has improved some of the best operating models for coordinated or
separate operation purposes, with the objective of generating the largest revenue for the
combined generation, in the market conditions competitive electricity in Vietnam.
(2) The results of calculating the regulation scheme and the instructions for the monthly
electricity generation of each reservoir and inter-reservoir are referenced by reservoir
owners in the operation of the reservoir system with the constraints of flood water level,
the water supply flow and the target is the maximum revenue benefit
6.

New contribution

(1) The dissertation has developed the problem and the program to coordinate the
reservoir to achieve the largest revenue, improve the efficiency of power generation
when entering the competitive electricity market.

2


(2) Adopt a program of calculations for reservoirs in the Chu River basin to re-examine

the program under constrained conditions of multi-objective operation. Propose a chart
to coordinate the operation of electricity generation to ensure energy security as
required by the moderation mechanism of the power system.
7.

Structure of the dissertation

Besides Introduction and Conclusion sections, the dissertation consists of 03
chapters as follows:
Chapter 1. Overview of cascade reservoir operational research and competitive
electricity markets
Chapter 2. Research on scientific and practical basis to improve the efficiency of
cascade reservoirs in the competitive power generation market.
Chapter 3. Apply calculation and analysis results to determine the operating trend for
the cascade reservoir in the Chu River.

CHAPTER 1 OVERVIEW OF CASCADE RESERVOIR OPERATIONAL
RESEARCH AND COMPETITIVE ELECTRICITY MARKETS
1.1 Studies on reservoir operation in the world
Afzali et al. (2008) studied the combined operation of Khersan hydropower system,
Iran by combining simulation and optimization algorithms with the objective of
generating a total of four reservoirs. The authors have applied the masterpiece to each
of the reservoirs and to all four reservoirs for comparison. The results show that the
combination of 4 reservoirs with the objective function will produce about 7.9% higher
electricity output than the total power of 4 reservoirs operating separately.
Daniel De Ladurantaye et al. (2009) studied the optimization of profitability from
hydropower. The study presents a coherent, randomized mathematical model to
maximize the return earned by selling electricity through dams and reservoirs in a spot
3

market (immediate payment). The first model is based on the specified electricity price
while the other model integrates randomly through the management of a tree of
potential price scenarios. Numerical results based on historical data demonstrate the
superiority of the random model on the deterministic model. It also shows that price
fluctuations affect the profitability of the random model.
1.2 Researches in Vietnam
Ho Ngoc Dung (2017) studied the operation regime in the best interests of Son La and
Hoa Binh reservoirs during the dry season, identified optimal set of runways, and used
a combination of coordination charts to focus on scientific research, algorithm
development and optimal problem modeling of reservoirs of hydropower. The results
can serve to develop a rational and sustainable operation process of the inter-reservoir
system to ensure optimum energy exploitation; downstream water supply is stable and
sustainable in the dry season. However, the lagoon system with mesh water upstream of
Son La is 0.5m and Hoa Binh is 0.2m, which is difficult to match with smaller capacity
and combined capacity reservoirs. The study also just study the optimal operating mode
for two reservoirs Son La and Hoa Binh, while two reservoirs upstream in Son La are
Ban Chat hydropower and Lai Chau hydropower has not put to participate in
optimizing the system that uses their calculated results in the design phase as a
boundary condition to consider the effect.
Le Ngoc Son (2017) studied the establishment of a scientific basis combining the model
of simulation - optimization - artificial intelligence, building the optimal model of
dynamic programming (DP) to propose the transport plan Optimal access to the
reservoir system includes the actual alteration of the water source and the need for
water use to improve the efficiency of electricity generation, meeting the downstream
water supply requirements for the Ba River basin. Simulation results verified with the
actual performance of Song Hinh hydropower station showed that the model proposed
by the author brings more efficiency. However, the period of calculation in the model
does not subdivide the difficult period corresponding to the short-term hydrological
forecast period of 10 days. The study also fails to take into account the randomness of

4


water demand and electrical systems that only incorporate constraints. Operational
constraints on water use and electricity systems in the competitive electricity market
need to be further researched in order to make the model more adaptable when water
demand for the economy- society and market conditions change.
1.3 General introduction of competitive electricity market
Competitive power markets have been established and are operating effectively in a
number of European, American and Australian countries. According to the electricity
market plan in Vietnam will develop through three levels and continue to be completed
after each test. When entering the competitive electricity market, long-term regulated
reservoirs will have the advantage of offering prices as well as flexible operation in
order to sell electricity at high price frames. Therefore, this is an advantage and also a
complex problem that requires the owners to take into account when planning power
generation as well as regulating the power generation reservoir, in order to bring about
high efficiency in the conditions of the hydrographic regime change.
1.4 Research orientation of the dissertation
The researches on reservoir operation in Vietnam and in the world show that the
authors focus on solving optimal problems of power generation, water supply as well as
flood control when applying different calculation methods. Some authors have also
examined the location of HPP in the national grid. However, there are currently no
studies that consider entering the competitive electricity market when looking for
optimal operating options for power generation reservoirs.
Based on a review of studies on the Chu River basin system, there is no specific study
on the combination of the Hua Na - Cua Dat system during power generation
operations. This is a gap, it should be studied because each system has its own
characteristics, and there is not any single algorithm or model as general to resolve
completely the reservoir system operating problem.

In terms of research methods, an overview shows that the DP method or DP
improvements are often used in the study of reservoir operation and are effective in
conducting a global optimization. In terms of optimal computation of revenue for two
5


cascade reservoirs, the dissertation selects a top-down recalculation method to compute
boundaries, and applies the bottom-up approach in Build a computational model that
matches the processing capabilities of the programming language. From the analysis of
the competitive electricity market, the model selection dissertation is the optimal
maximum revenue for the staged reservoir when entering the electricity market.

Figure 1.10 The diagram shows the research steps
1.5 Conclusion of chapter 1
At present, in the Ma River basin in particular and the big river basins in Vietnam in
general, the Government has issued the inter-reservoir operating procedure which sets
out the operating rules. However, the owners still have the right to actively operate and
coordinate operations within the scope or binding permissions.
The operation, according to the new process, is currently halting the introduction of
water or discharge constraints, to ensure minimum facility safety and water supply,
without optimizing it. In addition, the operation is in the "equivalent to the design and

6


construction process", that is the operating instructions on the coordination chart remain
relatively fixed; update the data over time to adjust. On the other hand, every year,
participating factories in the competitive electricity market are assigned different
outputs. Distributions in the months of the year also change between years. As a result,
more appropriate modes of operation for the cascade reservoir system are needed to

improve the efficiency of power generation combined with flood prevention and water
supply and overcome other bottlenecks in the operation of the hydro power system.
Analysis of the unresolved aspects of the previous studies in Chapter 1, which is the
basis for calculating and solving the problem of the operation of the reservoir
generation of the dissertation. Consequently, the approach and approach is the optimal
combination of power generation in the competitive market and the reservoir steps that
will be addressed in the next two chapters.

CHAPTER 2 RESEARCH ON SCIENTIFIC AND PRACTICAL BASIS TO
IMPROVE THE EFFICIENCY OF CASCADE RESERVOIR IN THE
COMPETITIVE ELECTRICITY MARKET
2.1 The optimal solution for inter-reservoir operation
The dissertation calculates inter-reservoir operation using the DP method, seeks to
optimize the target on the basis of historical flow and historical electricity purchase
data. From there, it is possible to determine the optimal positions in the operation and to
produce actual operating directions on time, following the water level of the reservoirs
at each operating point for the reservoir owners, The reservoirs can operate singly or in
combination to increase total revenue for the system
2.2 Solution for DP methodology
2.1.1

Selections for approaches

DP usually use following approaches:

7


 top-down: The problem is divided into sub-problems. Sub-problems solved and
solutions can be memorized in case of re-use. This is recursive and archives are

combined together.
 bottom-up: All problems that may be needed are solved first, and then used to
construct solutions for larger problems. This approach is better for the memory
space used for the stack and the number of function calls.
To avoid having to solve multiple sub-problem problems (DP top-down), the
dissertation uses the DP bottom-up method to calculate and define the maximum
revenue function; In order to construct the water margin to ensure energy security, the
dissertation utilizes a top-down approach with a set of starting points reversing from the
last dead water level complex of reservoirs
2.1.2

Specifications of DP

The target function is the maximum or minimum target to be achieved. This is a
measure of effectiveness, of decision making at each stage. This function will depend
on the state, state and end state of the interconnected system. The goal, which may be
the greatest benefit to be achieved such as the dry season power, for year or more years,
or the least cost of water damage or loss. In the dissertation, with the subject of
reservoir belonging to private owners, the objective function was selected as the interreservoir revenue and the largest reservoir for the years of operation.
The transition period (for the next period) needs to record the path values that make up
the target function in all meshes (which are in the calculation period). In each pair of
divided lattices (two reservoirs), it is necessary to determine the appropriate path from
the starting point (first pair of meshes) to the meshes in question.
2.3 Calculate optimal regulation of reservoir of hydropower station by DP
2.3.1

Single reservoir calculation model

8

Figure 2.2 Describe the optimal path directions in reservoir regulation
Step 1: Divide calculation cycle T into n period ΔT.
Step 2: Then carry out iterations to narrow down the dividing net of ΔZ = 0.1m.
Step 3: Number the corresponding meshes Zi,k with i is the period in the calculation
cycle T and k is the mesh position.
Step 4: Let the comparison algorithm be implemented and assign a new value (greater
than the old value) found in the meshes: In the case of finding the largest value, with
the incremental values being positive, the initial value at the grid points needs to be
assigned to a value less than 0. Assign revenue value at all points on the mesh Bj,k = –1.
Step 5: Select the starting point and assign the revenue value at the starting point Bo = 0.

9


Step 6: Link point Zo to all points: Z1,1; Z1,2; ... to Z1,m-3; Z1,m-2; Z1,m-1; Z1,m determine the
difference of the head capacity and the end of the period for each point ΔV1,1; ΔV1,2; ...
to ΔV1,m-3; ΔV1,m-2; ΔV1,m-1; ΔV 1,m.
(mil. m3/s)

∆𝑉1,𝑘 = 𝑉 𝑍1,𝑘 − 𝑉 𝑍𝑜

(2-6)

With V(Z) is the value of the reservoir capacity corresponding to the upstream water
level Z, interpolation according to the relationship between water level and reservoir
volume. Use this volume difference; The program calculates the flow out of the
reservoir. If the flow-rate is negative, Search values at that point are assigned value -1.
If the flow out of the reservoir ensures the minimum flow of the corresponding period,
The values for water head, capacity, power and revenue at that point will be saved.

Step 7: Determine the flow out of the reservoir in the mesh according to the following
general formula:
𝑄1,𝑘 = 𝑄1𝑎𝑐𝑡𝑢𝑎𝑙 −

∆𝑉 1,𝑘
∆𝑇

(m3/s)

− 𝑄𝑙𝑜𝑠𝑠

(2-7)

With 𝑄1đế𝑛 is the actual flow to the reservoir in period 1; Qloss is the flow loss due to
evaporation and permeability in the corresponding period.
Step 8: Check if conditions 𝑄1,𝑘 ≥ 𝑄1𝑚𝑖𝑛 satisfied, it will calculate the basic
hydroelectricity to determine the increased amount of electricity due to the change in
water level Zo to Z1,k in period 1.
𝐸1,𝑘 = 𝑁1,𝑘 ∆𝑇

(mil. kWh)

(2-8)

Step 9: Determine the corresponding revenue, by calculating the contract output for
period 1; contract prices; the level of distribution of electricity generation hours in the
history of electricity trading; ceiling price of period 1. Values will be assigned B1,k at
the meshes Z1,k If there is a reasonable path from Zo to Z1,k. In case, there is no
reasonable path in the mesh Z1,k, value of B1,k still equals –1.

10


Step 10: Determine the average price of the period, based on the amount of electricity
generated (KB1) or the number of hours taking advantage of the available capacity of
the period (KB2).
−1 𝑖𝑓 𝑤𝑖𝑡ℎ 𝑘 ℎ𝑎𝑠 𝑄𝑜1,𝑘 < 𝑄1𝑚𝑖𝑛
𝐵1,𝑘 =

(2-9)
𝐵0 + ∆𝐵𝑜1,𝑘 𝑖𝑓 𝑎𝑡 𝑝𝑜𝑖𝑛𝑡 𝑘 𝑒𝑥𝑖𝑠𝑡 𝑄𝑜1,𝑘 ≥ 𝑄1𝑚𝑖𝑛

Step 11: Determine the increase in revenue due to the change in water level during the
period 1 from Zo to Z1,k is ∆𝑩𝟏,𝒌
𝒐 .
Step 12: Add revenue values from B at Zo is Bo = 0, with revenue increase due to
changing water levels Zo to Z1,k get value B1,k at Z1,k.
The results obtained are all B1,k , are positive values if there is a path from Zo to Z1,k and
are values -1, if there is no path from Zo to Z1,k. At this step, if the values B1,k positive,
path to Z1,k will be saved as derived from Zo.
Step 13: Repeat steps 6 through 12, for the third time. With the determination, see
which path brings the largest revenue B2,k at Z2,k. In this step, if B2,k > 0, path to Z2,k,
will be saved as a line derived from one of the meshes Z1,j through comparison.
−1 𝑖𝑓 ∀ 𝑗 𝑡ℎ𝑒 𝑣𝑎𝑙𝑢𝑒

𝐵1,𝑗

2,𝑘
𝑄1,𝑗
< 𝑄2𝑚𝑖𝑛

<0

𝐵2,𝑘 =

(2-10)
2,𝑘
𝑚𝑎𝑥 𝐵1,𝑗 + ∆𝐵1,𝑗
𝑖𝑓 ∃ 𝑗 𝑤𝑖𝑡ℎ

2,𝑘
𝑄1,𝑗

≥

𝑄2𝑚𝑖𝑛

𝐵1,𝑗 ≥ 0

Step 14: Repeat steps 6 through 13, until the end of the calculation cycle is Bn,k.
Knowing the water level to reach at the end; from the chain equation system will find
the previous values. From there, determine the optimal single-track operation line to
obtain the largest revenue for the calculation cycle of T.

2.3.2

Model calculates cascade reservoir

At each calculation step (the calculation period is between two consecutive calculation
periods), for example if there are two terraced reservoirs, the program considers the pair
11

of upstream water levels on the upper and lower reservoirs (Ztl_up, Ztl_down) as one point
comes from many points (upstream water pair) from the previous point, and also
considering all possible directions to the point of consideration.
The diagram is illustrated in Figure 2.3.

Ztl_up
Ztl_up

time

Ztl_up

Ztl_down
Ztl_down
Ztl_down
Figure 2.3 The model gathers directions such as two reservoirs

Check the selection of values assigned to array points at the time j+1 when considering
separate increases due to different directions to it from time to time j. For example,
indicators are assigned to 2 pools in the calculation program: i is the number of years; j
is the time index of the year; k1 is the reservoir water level at the beginning of the
period; k2 is the reservoir water level at the end of the period; l 1 is the reservoir water
level below the beginning of the period; l2 is the reservoir water level below the end of
the period.
2.4 Optimal model for cascade reservoirs
The objective function is shown as follows:

𝑅𝑒𝑣𝑒𝑛𝑢𝑒 = 𝑃𝑜𝑤𝑒𝑟 𝑜𝑢𝑡𝑝𝑢𝑡 × 𝑃𝑟𝑖𝑐𝑒 → 𝑚𝑎𝑥

𝑁

𝑀

(2-11)

𝐿

𝐸𝑖,𝑗,𝑙 × 𝑏𝑖,𝑗,𝑘 → 𝑚𝑎𝑥
𝑖=1 𝑗=1 𝑘=1

With: i index year; i = 1 ÷ N with N is total calculate year;
j is the period index of the year; j = 1 ÷ M with M is total period in year;
12

(2-12)


k is the reservoir index in the system; k = 1 ÷ L with L is the total number of reservoirs;
bi,j,k is the average selling price of electricity changed according to the output of
electricity generated Ei,j,k of reservoir k in period j of year i.
2.5 Method of constructing and solving inter-reservoir operation problem in Chu
River basin
Case 1 can get the boundary of the boundary water level, the first constraint. The
downstream water level is the second priority. If the downstream water level is not
guaranteed and the water level is lowered to the lowest level, only the possible value of
the downstream water level will be taken into account.
Case 2 may prioritize the water supply frontage, if the water level has not touched the
dead water level, then continue to supply water to meet the requirements. If the water
level hits the dead water level, the downstream flow is just the flow to the reservoir.

The dissertation considers two priority cases of flow or water level and selects a priority
case for water level to consider the water supply values and calculates the combination
of two reservoirs according to the different targets: largest revenue, largest power to
compare and test results
For the year-end hydropower station, the starting point for calculation should be
selected. At this point, there should be less upstream fluctuations or periods of division
in the early flood season or early dry season.
Within the scope of the dissertation, the calculation period is the month and the time of
July 1 is the beginning of the flood season for calculation.
The dissertation uses the DP up-down method from 30 June to 1 July of the previous
year, to consider setting the boundary for the optimal path and coordinate diagrams for
the cases. The output of the contracted power year is different.

13


2.6 Flow chart and equations for cascade hydropower system
The computation involves the process of forward swing to find the final result value
(for comparison purposes) and the retrograde retrieval process to retrieve the data that
produces the final result.
Downstream process: When the water level at the beginning and end of the reservoir or
reservoir steps is known, parameters such as electricity generation, electricity
generation, power, electricity and sales are measured. count out. In this process, the
relation of the water balance equation to the system needs to be calculated to generate
the flow input for the down-stream reservoir. Constraints are the inequities to verify
that they meet the constraints of power, water level, flow, and to retain the optimal
assurance process that has been compared to the defined extremes. . In cases where the
minimum flow constraint at some stage is not satisfactory, but the water level at the
beginning and end of the period has been the minimum water level, the program
continues to calculate to ensure continuity between periods.

The back-ward process, in order to retrieve the saved path to the final cumulative
revenue, achieves optimum results. If it is a yearly regulator, it only needs to be
recaptured by year. Find from end of year back to started point. If it is the regulator for
many years, it must be recaptured from last year to first year.
2.7 Construct calculation program
The main calculation block diagram is shown in Figure 2.6, which contains five loops
(one loop is the monthly period in the calculation year, the next four loops are the
reservoir water level including the two water level loop phase and two end-of-period
water level loops) to find the maximum target function value. At the beginning of the
comparison, the net turnover at the end of the period if less than the increase in revenue
between the two meshes plus the net turnover at the beginning of the period, the new
revenue would be attributed to the net position at the end period.

14


Figure 2.6 Flow chart for calculates maximum revenue
15


Figure 2.7 Flow chart creates bounding margins for single reservoir water level
2.8 Conclusion of chapter 2
To build the scientific basis for the optimal model of the cascade reservoir system and
apply specifically to the two reservoirs, expressed through the combination of water
16


levels at determined time points, the value of electricity, electricity, average electricity
price of the period to obtain the result is the largest revenue target function. Here, the
constraints on water supply, water level, capacity, etc. shall be considered and strictly

complied with inter-reservoir operation procedures in the Ma River basin issued by the
Prime Minister. One of the most prominent issues of the dissertation is to take into
account the power price factor in the optimal operation of interconnected reservoirs.
In order to solve the optimal operation problem, the dissertation was programmed in
Visual Basic 2010 in Windows operating system to process data, evaluate the result and
link data to output the graph, integrated management, inter-reservoir power generation
in the Chu River basin.
CHAPTER 3 APPLY CALCULATION AND ANALYSE RESULTS TO
DETERMINE THE OPERATION TREND FOR CASCADE RESERVOIRS IN
CHU RIVER
3.1 Operational characteristics and shortcomings in the Chu River basin
At present there are two reservoirs with the ability to regulate the year is Hua Na
reservoir and Cua Dat reservoir. The Chu River section from the downstream of Hua
Na reservoir to Cua Dat reservoir is about 40km long with rather steep terrain; there is
no exploitation and direct use of water on the mainstream of Chu River.
3.2 Develop a coordinated flowchart to ensure the contracted output of the two
Hua Na and Cua Dat reservoirs in the competitive electricity market in
Vietnam.
The dissertation applies the DP method, inter-reservoir regulation to obtain the best
operating guidelines for years, the optimum working range when the water level is less
volatile. In order to achieve revenue in the competitive electricity market, apart from
taking the initiative in generating electricity, each factory needs to set up a scenario to
increase or decrease the average electricity price by the electricity output or monthly
electricity selling price.
In order to limit the volume of calculations, the dissertation builds and uses lines to
ensure the output of contracts to create upstream water margins for reservoir
computation.
17

The dissertation proposes two price scenarios, which are applied to the calculation to
obtain different results, from which analyzes and evaluates which scenarios are suitable
for the applied case.
245

Water level (m)

240

III

235

II

230
225

II
IV

I

220
215
210

01-07 01-08 01-09 01-10 01-11 01-12 01-01 01-02 01-03 01-04 01-05 01-06 01-07
Time (month)

Figure 3.5 Coordinated flowchart to ensure the contracted output 2016-2017
245

Water level (m)

240

III

235
230
225
220

II
I

IV

215
210
01-07 01-08 01-09 01-10 01-11 01-12 01-01 01-02 01-03 01-04 01-05 01-06 01-07
Time (month)

Figure 3.6 Coordinated flowchart to ensure the contracted output 2017-2018
Coordinated flowchart of two hydrology years 2016-2017 and 2017-2018 of Hua Na
HPP being shown differently by Qc required every year is different.

18

3.3 Price scenario
The price data is collected through each hour of selling electricity, summarizing the day
of selling electricity, synthesizing the months of selling electricity and the whole year
selling electricity. Based on this data, it can be divided into average prices in flood
season, average prices in dry season, price in months, divided by reliability of
electricity generation capacity, divided by variable Quantity. Within the scope of the
dissertation, there are two scenarios for price variation to be taken into consideration:
the monthly price change of seasons in the year (KB1), the construction and use of the
electricity price maintenance curve month (KB2).

Hua Na HPP

Rainy season
1400
1200
1000
800
600
400
200
0

1400
1200
1000
800
600
400
200

0

y = -2.881x + 1101.
R² = 0.390
0

Cua Dat HPP

Dry season

50

100

150

y = 2.709x + 946.3
R² = 0.184
0

1000

1200

800

1000

20

40

60

80

800

600

600
400

400

y = -2.253x + 757.2
R² = 0.157

200

y = 4.174x + 628.0
R² = 0.274

200

0

0
0

20

40

60

80

0

20

40

60

Monthly price (VND/ kWh on vertical axis) correlates with monthly electricity (million
kWh on horizontal axis) in the rainy season and dry season of Hua Na and Cua Dat
HPPs.

19


3.4 Result of scenario 1 (KB1)
Due to the increase in price correlation with increasing electricity volume in the dry
season, in practice there will be more exhausting months of electricity generation than
the rest of the year, or the trend of high- intermittently low power months
Optimum boundary of Hua Na HPP
245

Water level (m)

240
235
230
225

Up boundary line

220

Down boundary line

215
210
01-07 01-08 01-09 01-10 01-11 01-12 01-01 01-02 01-03 01-04 01-05 01-06 01-07
Time (month)

Figure 3.32 Hua Na optimal operating range takes into account the minimum flow
Optimum boundary of Cua Dat HPP
115

Water level (m)

110
105
100

95
90

85
80
75
70
01-07 01-08 01-09 01-10 01-11 01-12 01-01 01-02 01-03 01-04 01-05 01-06 01-07
Time (month)

Figure 3.33 The optimal range of Cua Dat operation after Hua Na optimizes revenue

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3.5 Result of scenario 2 (KB2)
The figures show that the actual water level is much lower than the upstream curve
when calculating the optimum. Thus, the operation plan is still far away from optimal
operation.
240

Water level (m)

235

230
225
220
215
1/7

1/8

1/9

1/10

1/11

1/12

1/1

1/2

1/3

1/4

1/5

1/6

1/7

Time (month)

Figure 3.37 Hua Na reservoir water level evolutions in the 2015-2016 using the
estimate 2014-2015
240

Water level (m)

235
230
225
220
215
1/7

1/8

1/9

1/10

1/11

1/12

1/1

1/2

1/3

1/4

1/5

1/6

1/7

Time (month)

Figure 3.38 Hua Na reservoir water level evolutions in the 2016-2017 using the
estimate 2015-2016

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240

Water lvel (m)

235
230
225
220
215
1/7

1/8

1/9

1/10

1/11

1/12

1/1

1/2

1/3

1/4

1/5

1/6

1/7

Time (month)

Figure 3.39 Hua Na reservoir water level evolutions in the 2017-2018 using the
estimate 2016-2017
The results of calculations under scenario 2 with the hydrology-years shown that the
combination of multi-reservoir operation will bring more efficiency when operating the
reservoir as well as actual operating results has occurred.
3.6 Select the electricity tariff scenarios for the system and the operating
instructions when operating in the competitive electricity market
Initial analysis of the price structure in two scenarios, the author noted that:
- Scenario 1: Compatibility with market prices is not appropriate when electricity price
is applied in the dry season due to some shortage of electricity so the electricity price
increases, so stations are mobilized much, simultaneously. The correlation coefficient
between the selling price of electricity and electricity is low
- Scenario 2 takes into account market factors when building the correlation between
the selling price of electricity and the accumulation of electricity generated for each

month and at the same time reflecting the market's rules.
Therefore, the proposal to choose the price of electricity sold under scenario 2 to apply
for the Chu River hydropower

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3.7 Conclusion of Chapter 3
When choosing the same optimal target, the difference in the calculation is: KB1
(Revenue from Electricity Generating Capacity), or KB2 (varied by the number of
hours sold) will result in models Different combinations of operations (in terms of
structure, drawings, and milestones are the same, but the results of each one are
different in each case).
The objective function, which can be changed to match the competitive power
generation, generates electricity at different estimated unit prices of the periods. The
boundary conditions can be narrowed, making the mesh narrower for closer inspection
and faster calculation. Detection techniques, computational corridors, and piping can be
used to calculate faster with more reservoirs. Upstream water levels, which can be split
at the beginning with longer distances, can be further subdivided after detecting a
combinational line.

CONCLUSION AND PROPOSAL
1. Achieved results of the dissertation
The dissertation has developed and presented the scientific basis for calculating the
different objective functions, setting the selling price based on monthly electricity
purchase data available in the history of operation. Based on the characteristics of the
annual regulator, the availability of electromechanical equipment and the purchase price
of electricity at high times during the day, the cost of generating electricity depends on
the main task of the reservoir.
The dissertation has applied, calculated and applied the calculation of the two main

reservoirs on the system of Chu River, indicating the optimal operating range,
calculating the determination of long-term regulations to create advantages for the plant
in offering competitive electricity to Vietnam.

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