45 research outputs found
Stochastic simulation of photovoltaic electricity feed-in considering spatial correlation
The growing generation capacity of electricity from renewable energy sources (RES-E) around the globe has an increasing impact on traditional energy and electricity markets. Well-ahead planned investment decisions as well as short term management of the power plant and storage dispatch and other challenges are highly dependent on the feed-in of RES-E. Therefore a thorough research of RES-E supply and knowledge about methods to generate corresponding model input is crucial when simulating electricity markets
Economically Operation of Power Utilities Base on MILP Approach
In this paper a new approach will be presented for solving one the complicated problems in power systems, known as the unit commitment. Indeed, in this paper, the proposed unit commitment is converted and formulated as the mixed-integer linear programming (MILP) model and solved by utilizing the Yalmip toolbox. Results demonstrates the high efficiency of the proposed method
Transmission Network Reduction Method using Nonlinear Optimization
This paper presents a new method to determine the susceptances of a reduced
transmission network representation by using nonlinear optimization. We use
Power Transfer Distribution Factors (PTDFs) to convert the original grid into a
reduced version, from which we determine the susceptances. From our case
studies we find that considering a reduced injection-independent evaluated PTDF
matrix is the best approximation and is by far better than an
injection-dependent evaluated PTDF matrix over a given set of
arbitrarily-chosen power injection scenarios. We also compare our nonlinear
approach with existing methods from literature in terms of the approximation
error and computation time. On average, we find that our approach reduces the
mean error of the power flow deviations between the original power system and
its reduced version, while achieving higher but reasonable computation times
An integrated OPF dispatching model with wind power and demand response for day-ahead markets
In the day-ahead dispatching of network-constrained electricity markets, renewable energy and distributed resources are dispatched together with conventional generation. The uncertainty and volatility associated to renewable resources represents a new paradigm to be faced for power system operation. Moreover, in various electricity markets there are mechanisms to allow the demand participation through demand response (DR) strategies. Under operational and economic restrictions, the operator each day, or even in intra-day markets, dispatchs an optimal power flow to find a feasible state of operation. The operation decisions in power markets use an optimal power flow considering unit commitment to dispatch economically generation and DR resources under security restrictions. This paper constructs a model to include demand response in the optimal power flow under wind power uncertainty. The model is formulated as a mixed-integer linear quadratic problem and evaluated through Monte-Carlo simulations. A large number of scenarios around a trajectory bid captures the uncertainty in wind power forecasting. The proposed integrated OPF model is tested on the standard IEEE 39-bus system
A Multiperiod OPF Model Under Renewable Generation Uncertainty and Demand Side Flexibility
Renewable energy sources such as wind and solar have received much attention
in recent years and large amount of renewable generation is being integrated to
the electricity networks. A fundamental challenge in power system operation is
to handle the intermittent nature of the renewable generation. In this paper we
present a stochastic programming approach to solve a multiperiod optimal power
flow problem under renewable generation uncertainty. The proposed approach
consists of two stages. In the first stage operating points for conventional
power plants are determined. Second stage realizes the generation from
renewable resources and optimally accommodates it by relying on demand-side
flexibility. The benefits from its application are demonstrated and discussed
on a 4-bus and a 39-bus systems. Numerical results show that with limited
flexibility on the demand-side substantial benefits in terms of potential
additional re-dispatch costs can be achieved. The scaling properties of the
approach are finally analysed based on standard IEEE test cases upto 300 buses,
allowing to underlined its computational efficiency.Comment: 8 pages, 10 figure
Quantification of operating reserves with high penetration of wind power considering extreme values
The high integration of wind energy in power systems requires operating reserves to ensure the reliability and security in the operation. The intermittency and volatility in wind power sets a challenge for day-ahead dispatching in order to schedule generation resources. Therefore,the quantification of operating reserves is addressed in this paper using extreme values through Monte-Carlo simulations. The uncertainty inwind power forecasting is captured by a generalized extreme value distribution to generate scenarios. The day-ahead dispatching model is formulated asa mixed-integer linear quadratic problem including ramping constraints. This approach is tested in the IEEE-118 bus test system including integration of wind power in the system. The results represent the range of values for operating reserves in day-ahead dispatchin
Linear/Quadratic Programming-Based Optimal Power Flow using Linear Power Flow and Absolute Loss Approximations
This paper presents novel methods to approximate the nonlinear AC optimal
power flow (OPF) into tractable linear/quadratic programming (LP/QP) based OPF
problems that can be used for power system planning and operation. We derive a
linear power flow approximation and consider a convex reformulation of the
power losses in the form of absolute value functions. We show four ways how to
incorporate this approximation into LP/QP based OPF problems. In a
comprehensive case study the usefulness of our OPF methods is analyzed and
compared with an existing OPF relaxation and approximation method. As a result,
the errors on voltage magnitudes and angles are reasonable, while obtaining
near-optimal results for typical scenarios. We find that our methods reduce
significantly the computational complexity compared to the nonlinear AC-OPF
making them a good choice for planning purposes