L. Duckstein at all. TWO real-life examples are presented to show how multicriterion de cision-

making (MCDM) techniques can help hydropower engineers mitigate the environmental and

social effects of hydropower development and operation. A brief introduction and overview of

MCDM is presented, consisting of an 11-step process that starts with problem definition and

ends with implementation. A typology of MCDM is provided, dividing the techniques into three

groups: outranking, distance-based, and value- or utility-based types. The operation of the Upper

Isar River project in Bavaria is analyzed by means of a value technique and an outranking

technique called multicriterion Q-analysis. Fourteen criteria are considered in that study,

including power production, habitat quality for four groups of species, aesthetics, several

recreation indices, minimum flows, and phosphorus loadings. The case study of the Erlauf River

Division in Austria is evaluated using a distance-based technique, called composite

programming, combined with Monte Carlo simulation. An outcome of that study is that the

facility's owners have increased the minimum instream flow in order to protect ecological values.

John W. Labadie With construction of new large-scale water storage projects on the wane in the

U.S. and other developed countries, attention must focus on improving the operational

effectiveness and efficiency of existing reservoir systems for maximizing the beneficial uses of

these projects. Optimal coordination of the many facets of reservoir systems requires the

assistance of computer modeling tools to provide information for rational management and

operational decisions. The purpose of this review is to assess the state-of-the-art in optimization

of reservoir system management and operations and consider future directions for additional

research and application. Optimization methods designed to prevail over the high-dimensional,

dynamic, nonlinear, and stochastic characteristics of reservoir systems are scrutinized, as well as

extensions into multiobjective optimization. Application of heuristic programming methods

using evolutionary and genetic algorithms are described, along with application of neural

networks and fuzzy rule-based systems for inferring reservoir system operating rules.

Q. Goor at all. Stochastic dual dynamic programming (SDDP) is one of the few methods

available to solve multipurpose-multireservoir operation problems in a stochastic environment.

This algorithm requires that the one-stage optimization problem be a convex program so that the

efficient Benders decomposition scheme can be implemented to handle the large state-space that

characterizes multireservoir operation problems. When working with hydropower systems, one

usually assumes that the production of hydroelectricity is dominated by the release term and not

by the head (storage) term to circumvent the nonlinearity of the hydropower production function.

Although this approximation is satisfactory for high head power stations for which the difference

between the maximum and the minimum head is small compared to the maximum head, it may

no longer be acceptable when a significant portion of the energy originates from low and/or

medium head power plants. Recent developments improve the representation of the nonlinear

hydropower function through a convex hull approximation of the true hydropower function. A

network of hydropower plants and irrigated areas in the Nile Basin is used to illustrate the

difference between the two SDDP formulations on the energy generation and the allocation

decisions.

Long Le Ngo at all. the largest reservoir in Vietnam, plays an important role in flood control for

the Red River delta and hydropower generation. Due to its multi-purpose character, conflicts and

disputes in operating the reservoir have been ongoing since its construction, particularly in the

flood season. This paper proposes to optimise the control strategies for the Hoa Binh reservoir

operation by applying a combination of simulation and optimisation models. The control

strategies are set up in the MIKE 11 simulation model to guide the releases of the reservoir

system according to the current storage level, the hydro-meteorological conditions, and the time

of the year. A heuristic global optimization tool, the shuffled complex evolution (SCE)

algorithm, is adopted for optimising the reservoir operation. The optimisation puts focus on the

trade-off between flood control and hydropower generation for the Hoa Binh reservoir operation

in the flood season and the reservoir level at the beginning of the dry season. The results

demonstrate that an optimized regulation can be found that compared to the present regulations

both reduces downstream flood peaks and maintains a high reservoir level for increasing the

hydropower production in the flood season and in the following dry season. The results also

show that the SCE algorithm is an efficient tool for optimising complex systems.

Henrik Lund at all. This paper presents a comparative study oftwo energy system analysis

models both designed for the purpose ofanalysing electricity systems with a substantial share

offluctuating renewable energy. The first model (EnergyPLAN) has been designed for national

and regional analyses. It has been used in the design ofstrategies for integration ofwind power

and other fluctuating renewable energy sources into the future energy supply. The model has

been used for investigating new operation strategies and investments in flexibility in order to

utilize wind power and avoid excess production. The other model (H2RES) has been designed

for simulating the integration of renewable sources and hydrogen into island energy systems. The

H2RES model can use wind, solar and hydro as renewable energy sources and diesel blocks as

backup. The latest version of the H2RES model has an integrated grid connection with the

mainland. The H2RES model was tested on the power system ofPorto Santo Island, Madeira,

Portugal, Corvo and Graciosa Islands, Azores Islands, Portugal and Sal Island, Cape Verde. This

paper presents the results of using the two different models on the same case, the island of Mljet,

Croatia. The paper compares methodologies and results with the purpose of identifying mutual

benefits and improvements of both models.

Nand Kishor at all. The recent increased number of black outs in the power system has been

largely due to growing competition and deregulation among the power industry. Power systems

are complex nonlinear systems and often exhibit low frequency electro-mechanical oscillations

due to insufficient damping caused by severe operating conditions. This needs an advanced

modeling and control techniques for effective control of power plants. In case of hydroelectric

plant the hydro turbine is a non-linear, non-stationary multivariable system whose characteristics

vary significantly with the unpredictable load on it and this presents a difficulty in designing an

efficient and reliable controller. A conservatively designed control fails to perform as expected.

Keeping this in mind, hydro plant control is an application area with an interesting set of

problems for control engineering people. Mainly some of these problems focus towards

regulation of turbine with large load variation in the power system. These problems have not

been adequately solved and continue to pose challenges to the control community. In this review

paper, the authors have tried to broadly categorize the research work done so far on the basis of

hydro plant model development and its controller design under different sections. A substantial

number of relevant research papers can be found on the plant modeling, design aspects of control

methodologies and their performance study.

Edgardo D. Castronuovo at all. Ambitious targets for renewable power production have been

defined for the electric power systems in Europe. The accomplishment of these targets requires

the increase in renewable energy production, namely from wind power generation. However, the

intermittent nature of wind creates several problems to the power system operation and new

approaches based on the combined use of wind power and energy storage technologies need to

be developed. In this paper, the concept of the combined use of wind power production and

hydro storage/production is exploited, through the development of an operational optimisation

approach applied to a wind generator park with little water storage ability. The optimisation

model defines the operational strategy to be followed for the hours ahead by a pump station and

an hydraulic generator embedded in a wind/hydro pumping facility, using the Portuguese energy

remuneration rules. The proposed methodology leads to considerable yearly profits for the wind

generator production.

Erlon Cristian Finardi at all. We describe a new model for the hydro unit commitment and

loading (HUCL) problem that has been developed to be used as a support tool for day-ahead

operation in the Brazilian system. The objective is to determine the optimal unit commitment and

generation schedules for cascaded plants with multiple units and a head-dependent hydropower

model. In this paper, we propose a new mathematical model for the hydropower function where

the mechanical and electrical losses in the turbine-generator are included. We model the HUCL

problem as a nonlinear mixed 0–1 programming problem and solve it with a strategy that

includes a two-phase approach based on dual decomposition. The computational tool allows the

model to effectively schedule hydro units for the problem in the Brazilian regulatory framework.

Application of the approach is demonstrated by determining a 24-time step HUCL schedule for

four cascaded plants with 4170 MW of installed capacity.

H. Lund at all. Combined Heat and Power production (CHP) are essential for implementation of

the climate change response objectives in many countries. In an introduction period, small CHP

plants have typically been offered fixed electricity prices, but in many countries, such pricing

conditions are now being replaced by spot market prices. Consequently, new methodologies and

tools for the optimisation of small CHP plant designs are needed. The small CHP plants in

Denmark are already experienced in optimising their electricity production against the triple

tariff, which has existed for almost 10 years. Consequently, the CHP plants have long term

experience in organising when to switch on and off the CHP units in order to optimise their

profit. Also, the CHP owners have long term experience in designing their plants. For instance,

small CHP plants in Denmark have usually invested in excess capacity on the CHP units in

combination with heat storage capacity. Thereby, the plants have increased their performance in

order to optimise revenues. This paper presents the Danish experience with methodologies and

software tools, which have been used to design investment and operation strategies for almost all

small CHP plants in Denmark during the decade of the triple tariff. Moreover, the changes in

such methodologies and tools in order to optimise performance in a market with fluctuating

electricity prices are presented and discussed.

Juan I. Pérez-Díaz at all. This paper presents a dynamic programming model to solve the short-

term scheduling problem of a hydropower plant that sells energy in a pool-based electricity

market with the objective of maximizing the revenue. This is a nonlinear and non-concave

problem subject to strong technical and strategic constraints, and in which discrete and

continuous variables take part. The model described in this paper determines, in each hour of the

planning horizon (typically from one day to one week), both the optimal number of units in

operation (unit commitment) and the power to be generated by the committed units (generation

dispatch). The power generated by each unit is considered as a nonlinear function of the actual

water discharge and volume of the associated reservoir. The dependence of the units’ efficiency

and operating limits with the available gross head is also accounted for in this model. The

application of this model to a real hydropower plant demonstrates its capabilities in providing the

operation schedule that maximizes the revenue of the hydro plant while satisfying several

constraints of different classes. In addition, the use of this model as a supporting tool to estimate

the economic feasibility of a hydropower plant development project is also analyzed in the paper.

S. Nikolova at all. This paper presents an approach for solving the generation scheduling

problem of a complex system consisted of conventional and renewable energy sources (RES).

Wind power plants are integrated into the system in order to minimize the total thermal unit fuel

costs. The gained results for wind farm power production are used as input in the system to

determine the optimal amounts of generated power for the thermal generating units and hydro

generating units over the study period. The optimization problem consists of minimizing the total

production costs, respecting power balance equations for each time interval and all operational

system constraints. The proposed approach is applied on a specific system consisted of thermal

power plants (TPPs), storage hydro power plants (HPPs), pumped-storage hydro power plant

(PSHPP) and wind power plant (WPP). The benefits of energy production from WPP, in terms of

reducing the production costs of conventional thermal power plants are also investigated. In the

proposed paper two cases are analyzed. In the two analyzed cases power unit’s generation,

thermal unit’s fuel costs and stream flows of hydro units are calculated over the study period.

D. Connolly at all. In this paper, three practical operation strategies (24Optimal, 24Prognostic,

and 24Hsitrocial) are compared to the optimum profit feasible for a PHES facility with a 360

MW pump, 300 MWturbine, and a 2 GWh storage utilising price arbitrage on 13 electricity spot

markets. The results indicate that almost all ( 97%) of the profits can be obtained by a PHES

facility when it is optimised using the 24Optimal strategy developed, which optimises the energy

storage based on the day-ahead electricity prices. However, to maximise profits with the

24Optimal strategy, the day-ahead electricity prices must be the actual prices which the PHES

facility is charged or the PHES operator must have very accurate price predictions. Otherwise,

the predicted profit could be significantly reduced and even become a loss. Finally, using the

24Optimal strategy, the PHES profit can surpass the annual investment repayments required.

However, over the 5-year period investigated (2005–2009) the annual profit from the PHES

facility varied by more than 50% on five out of six electricity markets considered. Considering

the 40-year lifetime of PHES, even with low investment costs, a low interest rate, and a suitable

electricity market, PHES is a risky investment without a more predictable profit.

A.M. Foley at all. Electricity systems models are software tools used to manage electricity

demand and the electricity systems, to trade electricity and for generation expansion planning

purposes. Various portfolios and scenarios are modelled in order to compare the effects of

decision making in policy and on business development plans in electricity systems so as to best

advise governments and industry on the least cost economic and environmental approach to

electricity supply, while maintaining a secure supply of sufficient quality electricity. The

modelling techniques developed to study vertically integrated state monopolies are now applied

in liberalised markets where the issues and constraints are more complex. This paper reviews the

changing role of electricity systems modelling in a strategic manner, focussing on the modelling

response to key developments, the move away from monopoly towards liberalised market

regimes and the increasing complexity brought about by policy targets for renewable energy and

emissions. The paper provides an overview of electricity systems modelling techniques,

discusses a number of key proprietary electricity systems models used in the USA and Europe

and provides an information resource to the electricity analyst not currently readily available in

the literature on the choice of model to investigate different aspects of the electricity system.

Juan I. Pérez-Díaz at all. This paper presents a novel approach to solve the short-term operation

scheduling problem of a hydropower plant that sells energy in a deregulated electricity market

with the objective of maximizing its revenue. This paper proposes a nonlinear programming

based scheduling model that determines both the optimal unit commitment (start-ups and shut-

downs scheduling) and the generation dispatch of the committed units (hourly power output).

The power generated by each hydro unit is considered as a nonlinear function of the water

discharge and the volume of the associated reservoir. The dependence of the units’ operating

limits (maximum and minimum water flows) on the actual gross head has been also taken into

account in this model. The results from a case study are also presented to illustrate the

application of the proposed approach in a real hydro plant.

Álvaro Jaramillo Duque at all. The participation of wind energy in electricity markets requires

providing a forecast for future energy production of a wind generator, whose value will be its

scheduled energy. Deviations from this schedule Because of prediction errors could imply the

payment of imbalance costs. In order to decrease these costs, a joint operation between a wind

farm and a hydro-pump plant is proposed; the hydro-pump plant changes its production to

compensate wind power prediction errors. In order to optimize this operation, the uncertainty of

the wind power forecast is modeled and quantified. This uncertainty is included in an

optimization problem that shifts the production of the hydro-pump plant in an optimal way,

aiming at reducing the imbalance costs. The result of such a method is profitable for participants,

the wind farm and the hydro-pump plant. A realistic test case is used to evaluate the proposed

method.

Filipe Vieira at all. Water supply systems (WSS) frequently present high-energy consumption

values, which correspond to the major expenses of these systems. Energy costs are a function of

its real consumption and of the variability of the daily energy tariff. This paper presents a model

of optimization for the energy efficiency in a water supply system. The system is equipped with a

pump station and presents excess of available energy in the gravity branch. First, a water turbine

is introduced in the system in order to use this excess of hydraulic available energy. Then, an

optimization method to define the pump operation planning along the 24 h of simulation, as

well as the analysis of the economic benefits resulting from the profit of wind energy to supply

the water pumping, while satisfying the system constraints and population demands, is

implemented, in order to minimize the global operational costs. The model, developed in

MATLAB, uses linear programming and provides the planning strategy to take in each time step,

which will influence the following hours. The simulation period considered is one day, sub-

divided in hourly time steps. The rules obtained as output of the optimization procedures are

subsequently introduced in a hydraulic simulator (e.g. EPANET), in order to verify the system

behavior along the simulation period. The results are compared with the normal operating mode

(i.e. without optimization algorithm) and show that energy cost’s savings are achieved

dependently of the initial reservoir levels or volume. The insertion of the water turbine also

generates significant economical benefits for the water supply system.

Alessandro Franco at all. Renewable energy sources (RES) are mainly used in the electrical

sector. Electricity is not a storable commodity. Hence it is necessary to produce the requested

quantity and distribute it through the system in such a way as to ensure that electricity supply and

demand are always evenly balanced. This constraint is actually the main problem related to the

penetration of new renewables (wind and photovoltaic power) in the context of complex energy

systems. Moreover the design of optimal energy resource mixes in climate change mitigation

actions is a challenge faced in many places. The paper analyzes the problem of new renewable

energy sources penetration. The case of Italian scenario is considered as a meaningful reference

due to the characteristic size and the complexity of the same. The various energy scenarios are

evaluated with the aid of a multipurpose software taking into account the interconnections

between the different energetic uses. In particular it is shown how the penetration of new

renewable energy sources is limited at an upper level by technological considerations and it will

be more sustainable if an integration of the various energy uses (thermal, mobility and electrical)

will be considered. A series of optimized scenarios are developed. In each case the maximum

RES penetration feasible with the constraints was defined. Then analysis is applied to an energy

system model of Italy showing how an integrated development of CHP and electric mobility can

aid a further integration of wind and photovoltaic energy power. Finally the primary energy

consumption saving possible in case of consistent penetration of intermittent renewables and

CHP was identified.

Hasmaini Mohamad at all. Hydro power generation is the oldest generation and provides the

largest contribution among the renewable energy types of generation. In distribution system,

most of the distributed generation (DG) is small scale hydro generation of which utilizes the

natural flowing water of the river. This generation requires governor and excitation control unit

to control and sustain the power generation when subjected to any changes of load behavior.

More advanced control strategy is critically expected when considering the recent interest in

distribution system to perform islanding operation of DG. Many of the literature have clearly

highlighted this issue, but only a few have discussed on the islanding operation of small hydro

generation. This paper therefore reviews this topic and relates the discussion with the controller

designed for other type of turbines interfaced with synchronous generator. To strengthen the

knowledge on islanding operation, the background of islanding is also presented in this paper.

S. Soares at all. This paper is concerned withthe optimal operation of reservoirs for electric

generation. It reports several tests carried out on a simple system under special conditions

highlighting some important characteristics of their optimal behavior. The tests were carried out

in a progressive way in order to make clear the influence of several factors including water head,

discount rate, inflow seasonality and system design. The main conclusions have been verified on

an actual large scale system, which demonstrated the conservative nature of the optimal

operation of reservoirs and the different roles they play according to their relative position in the

cascade. The conclusions address the issue of adequately modelling the long term hydrothermal

scheduling problem. The results suggest that the assumption of parallel operation of reservoirs,

implicit in composite reservoir models and some simulation heuristics, could be a modelling over

simplification.

Birger MO at all. his paper describes the structure and identification of a price model that is

used in stochastic optimization of hydro operation and flexible contracts. The price model must

be simple in order to be applicable in a stochastic optimization framework and the model

should incorporate as much of the statistics of the price process as possible. Modelling of

extremes is an important factor for the simulation capabilities of the optimisation models. The

paper shows examples of simulated optimal operation of hydropower plants with the new price

model. The paper also shows how the price model is used in a model that integrates hydro

operation and financial hedging. In the forward market, prices of contracts with delivery several

years ahead vary from one week to the next. In order to model this long-term uncertainty we

have amended our spot price model.

Patricia Teixeira Leite at all. This paper investigates the application of genetic algorithms to

optimize large, nonlinear complex systems, particularly the optimization of the operation

planning of hydrothermal power systems. Several of the current studies to solve this kind of

problem are based on nonlinear programming. This approach presents some deficiencies, such as

difficult convergence, oversimplification of the original problem or difficulties related to the

objective function approximation. Aiming to find more efficient solutions for this class of

problems, this paper proposes and investigates the use of a genetic approach. The characteristics

of the GAs such as simplicity, parallelism, and generality, can provide an effective solution to

these problems. The paper presents an adaptation of the technique and an actual application on

the optimization of the operation planning for a cascade system composed by interconnected

hydroelectric plants.

Kai Sun at all. System splitting problem (SS problem) is to determine proper splitting points (or

called splitting strategies) to split the entire interconnected transmission network into islands

ensuring generation/load balance and satisfaction of transmission capacity constraints when

islanding operation of system is unavoidable. For a large-scale power system, its SS problem is

very complicated in general because a combinatorial explosion of strategy space happens. This

paper mainly studies how to find proper splitting strategies of large-scale power systems using an

OBDD-based three-phase method. Then, a time-based layered structure of the problem solving

process is introduced to make this method more practical. Simulation results on IEEE 30- and

118-bus networks show that by this method, proper splitting strategies can be given quickly.

Further analyses indicate that this method is effective for larger-scale power systems.

Gregor Verbi at all. One of the tasks of the system operator (SO) is to control the frequency of

the system within defined limits. In order to do this, the SO has to provide enough power

reserves which can be provided on the basis of bilateral contracts or on the relevant competitive

market. In this paper, several methods for the power-reserve pricing of frequency control are

presented. These methods are well suited to small power systems, where an insufficient number

of potential bidders makes an ancillary-services market difficult to organize. The proposed

pricing methods are meant for estimating the annual costs for power-reserves provision when

these reserves are provided on the basis of bilateral con- tracts. The proposed pricing methods

are applied to the Slovenian power system.

M. E. El-Hawary at all. The present paper deals with the computational aspects of the

coordination equations for hydrothermal sheduling. The hybrid method of Powell is pro- posed

and its details are given. The method avoids possible causes for divergence encountered with the

application of Newton-Raphson method. As a result a very reliable and efficient algorithm for

fast solution of coordination equations emerges. Comprehensive testing of the performance of

the method in comparison with Newton's is offered in the text. It is concluded that the method

should be used whenever Newton's method is suspected to give doubtful performance.

H. Brannlund at all. This paper presents a procedure for solving the short term generation

scheduling oroblem for a large hydrothermal systen that includes transmission li- mitations. The

integrated system is divided into a hydro and a thermal subsystem. A reduced gradient algorithm

is employed for the solution of the hydro subproblem. This algorithm is specialized to efficiently

solve nonlinear netwrk flow problems with additional constraints of nm- netwrk type. The

thermal subsystem is solved using a fast unit ccnnitxrent and dispatch algorithm. A case study

with the Swedish system is discussed.

Phuc Diem NGUYEN NGOC at all. To limit the impact of the intermittence of wind power, a

water storage ability of the hydraulic storage plant combined with a wind power plant, called the

wind-hydro power system (WS), is used The main objective is to limit the active power output

variations of wind energy resource taking into account the grid needs and the available stored

energy. The problem is formulated as an optimization problem with constraints by using the

linear programming (LP). Based on the forecast information of the wind power, the power

demand of the grid, the penalty cost, an optimal operation strategy is proposed to help the WS

system for better using of wind energy and storage management. An example study case is

presented. A comparison with classical approach of economic gain is also given to illustrate the

interest of the proposed method.

C. P. Ion at all. This paper presents a control strategy that aims to improve the parallel operation

of two micro hydro power plants (MHPP) on an islanded micro-grid (MG). The two MHPP are

equipped with a synchronous (SG) and an induction generator (IG). The proposed control

systems ensures voltage and frequency regulation. The voltage is kept constant by the SG

voltage controller, while the frequency by the use of a dump load circuit (SL). Besides this, the

control system ensures active and reactive power management in order to reduce energy losses

and optimize hydraulic resources utilization. Simulations are carried out in order to highlight the

reliability of such a configuration.

Chun-Tian Cheng at all. Genetic algorithms (GA) have been widely applied to solve water

resources system optimization. With the increase of the complexity and the larger problem scale

of water resources system, GAs are most frequently faced with the problems of premature

convergence, slow iterations to reach the global optimal solution and getting stuck at a local

optimum. A novel chaos genetic algorithm (CGA) based on the chaos optimization algorithm

(COA) and genetic algorithm (GA), which makes use of the ergodicity and internal randomness

of chaos iterations, is presented to overcome premature local optimum and increase the

convergence speed of genetic algorithm. CGA integrates powerful global searching capability of

the GA with that of powerful local searching capability of the COA. Two measures are adopted

in order to improve the performance of the GA. The first one is the adoption of chaos

optimization of the initialization to improve species quality and to maintain the population

diversity. The second is the utilization of annealing chaotic mutation operation to replace

standard mutation operator in order to avoid the search being trapped in local optimum. The

Rosenbrock function and Schaffer function, which are complex and global optimum functions

and often used as benchmarks for contemporary optimization algorithms for GAs and

Evolutionary computation, are first employed to examine the performance of the GA and CGA.

The test results indicate that CGA can improve convergence speed and solution accuracy.

Furthermore, the developed model is applied for the monthly operation of a hydropower

reservoir with a series of monthly inflow of 38 years. The results show that the long term average

annual energy based CGA is the best and its convergent speed not only is faster than dynamic

programming largely, but also overpasses the standard GA. Thus, the proposed approach is

feasible and effective in optimal operations of complex reservoir systems.

Deepak Kumar Lal at all. A large proportion of the world’s population lives in remote rural

areas that are geographically isolated and sparsely populated. This paper proposed a hybrid

power generation system suitable for remote area application. The concept of hybridizing

renewable energy sources is that the base load is to be covered by largest and firmly available

renewable source(s) and other intermittent source(s) should augment the base load to cover the

peak load of an isolated mini electric grid system. The study is based on modeling, simulation

and optimization of renewable energy system in rural area in Sundargarh district of Orissa state,

India. The model has designed to provide an optimal system conFigureuration based on hour-by-

hour data for energy availability and demands. Various renewable/alternative energy sources,

energy storage and their 3 applicability in terms of cost and performance are discussed. The

homer software is used to study and design the proposed hybrid alternative energy power system

model. The Sensitivity analysis was carried out using Homer program. Based on simulation

results, it has been found that renewable/alternative energy sources will replace the conventional

energy sources and would be a feasible solution for distribution of electric power for stand alone

applications at remote and distant locations.

Bin Xu at all. Seeking the optimal strategy of a multi-reservoir system is an important approach

to develop hydropower energy, in which the Genetic Algorithm (GA) is commonly used as an

effective tool. However, when the traditional GA is applied in solving the problem, the

constraints of water balance equation, hydraulic continuity relationship and power system load

demand might be violated by the crossover and mutation operator, which decreases the

efficiency of the algorithm in searching for a feasible region or even leads to a convergence on

an infeasible chromosome within the expected generations. A modified GA taking stochastic

operators within the feasible region of variables is proposed. When determining the feasible

region of constraints, the progressive optimal approach is applied to transform constraints

imposed on reservoirs into a singular-reservoir constraint, and a joint solution with consideration

of adjacent periods at crossover or mutation points is used to turn the singular-reservoir

constraints into singular variable constraints. Some statistic indexes are suggested to evaluate the

performances of the algorithms. The experimental results show that compared to GA adopting a

penalty function or pair-wise comparison in constraint handling, the proposed modified GA

improves the refinement of the quality of a solution in a more efficient and robust way.

Omid Bozorg Haddad at all. This paper addresses a strategy for the optimal design, control and

operation of small hydropower (run-of-river (RoR) power) plants with the honey bee mating

optimisation (HBMO) algorithm, while taking into account optimal design of the associated

penstock as well as the turbines’ number, type and their operation in the system. Civil

engineering and electromechanical cost-effectiveness and constraints in an expected stream flow

are also considered. The optimisation is driven by an objective function that includes the annual

difference between generated energy, operating costs and depreciation costs for both initial

investment and operation costs, considering various performance and hydraulic constraints. The

HBMO algorithm specifies the annual benefit of generated energy and simultaneously

determines the annualised operating cost. The solution includes selection of turbine types,

number of turbines, penstock diameter, as well as scheduling the operation of an RoR power

plant that results in maximum annualised benefit for a given set of river inflow histograms. The

results of the proposed algorithm, which are compared with those of an analytical approach using

Lagrange multipliers (LM), highlight the advantages in design, effective operation, ease of

application and capability of the proposed HBMO algorithm for solving complex problems of

this type.

JAN C. GRYGIER at all. Successive linear programming, an optimal control algorithm, and a

combination of linear programming and dynamic programming (LP-DP) are employed to

optimize the operation of multireservoir hydrosystems given a deterministic inflow forecast. The

algorithm maximize the value of energy produced at on-peak and off-peak rates, plus the

estimated value of water remaining in storage at the end of the 12-month planning period. The

LP-DP algorithm is clearly dominated: it takes longer to find a solution and produces

significantly less hydropower than the other two procedures. Successive linear programming

(SLP) appears to find the global maximum and is easily implemented. For simple systems the

optimal control algorithm finds the optimum in about one fifth the time required by SLP but is

harder to implement. Computing costs for a two-reservoir, 12-month deterministic problem

averaged about seven cents per run using optimal control and 37 cents using successive linear

programming.

WILLIAM W-G. YEH The objective of this paper is to review the state-of-the-art of

mathematical models developed for reservoir operations, including simulation. Algorithms and

methods surveyed include linear programming (LP), dynamic programming (DP), nonliner

programming (NLP), and simulation. A general over view is first presented. The historical

development of each key model is critically reviewed. Conclusions and recommendations for

future research are presented.