1 Introduction General Background The New Computer Environment Transmission System Developments Theoretical Models and Computer Programs

Transcription

1 Modeling Techniques in Power Systems 1 General Background The New Computer Environment Transmission System Developments Theoretical Models and Computer Programs 2 Transmission Systems Linear Transformation Techniques Basic Single-phase Modeling Transmission lines Transformer on nominal ratio Off-nominal transformer tap representation Phase-shifting representation Three-phase System Analysis Discussion of the frame of reference The use of compound admittances Rules for forming the admittance matrix of simple networks Network subdivision Three-phase Models of Transmission Lines Series impedance Shunt admittance Equivalent 7r model Mutually coupled three-phase lines Consideration of terminal connections Shunt elements Series elements Line sectionalization Evaluation of Overhead Line Parameters Earth impedance matrix

2 Geometrical impedance matrix and admittance matrix Conductor impedance matrix Series impedance approximation for electromagnetic transients Underground and Submarine Cables Three-phase Models of Transformers Primitive admittance model of three-phase transformers Models for common transformer connections Three-phase transformer models with independent phase tap control Sequence components modeling of three-phase transformers Formation of the System Admittance Matrix 3 FACTS and HVDC Transmission Flexible a.c. Transmission Systems Thyristor controlled series compensator (TCSC) Static on-load tap changing Static phase shifter Static VAR compensator The static compensator (STATCOM) Unified power flow controller (UPFC) High Voltage Direct Current Transmission The a.c.-d.c. converter Commutation reactance d.c. link control Three-phase model Load Flow Basic Nodal Method Conditioning of Y Matrix

3 The Case Where One Voltage is Known Analytical Definition of the Problem Newton-Raphson Method of Solving Load Flows Equations relating to power system load flow Techniques Which Make the Newton-Raphson Method Competitive in Load Flow Sparsity programming Triangular factorization Optimal ordering Aids to convergence Characteristics Newton-Raphson Load Flow Decoupled Newton Load Flow Fast Decoupled Load Flow Convergence Criteria and Tests Numerical Example Load Flow for Stability Assessment Post-disturbance power flows Modeling techniques Sensitivity analysis Three-phase Load Flow Notation Synchronous machine modeling Specified variables Derivation of equations Decoupled three-phase algorithm Structure of the computer program 5 Load Flow under Power Electronic Control Incorporation of FACTS Devices Static tap changing Phase-shifting (PS)

4 Thyristor controlled series capacitance (TCSC) Unified power flow controller (UPFC) Incorporation of HVDC Transmission Converter model Solution techniques Control of converter a.c. terminal voltage Extension to multiple and/or multiterminal d.c. systems d.c. convergence tolerance Test system and Numerical example 6 Electromagnetic Transients Background and Definitions Numerical Integrator Substitution Resistance Inductance Capacitance Transmission Lines and Cables Bergeron line model Multi-conductor transmission lines Frequency-dependent model Formulation and Solution of the System Nodal Equations Modification for switching and varying parameters Non-linear or time varying parameters Use of Subsystems Switching Discontinuities Voltage and current chatter due to discontinuities Root-matching Technique Exponential form of difference equation Root-matching implementation Numerical illustration

5 a.c./d.c. Converters Synchronous Machine Model Transformer Model The PSCAD/EMTDC Program Structure of the program PSCADIEMTDC PSCADIEMTDC test cases Real Time Digital Simulation State Variable Analysis State variable formulation Solution procedure Choice of state variables 7 System Stability The form of the equations Frames of reference Synchronous Machines-Basic Models Mechanical equations Electrical equations Synchronous Machine Automatic Controllers Automatic voltage regulators Speed governors Hydro and thermal turbines Modeling lead-lag circuits Loads Low-voltage problems The Transmission Network Overall System Representation Mesh matrix method Nodal matrix method

6 Synchronous machine representation in the network Load representation in the network System faults and switching Integration Problems with the trapezoidal method Programming the trapezoidal method Application of the trapezoidal method Structure of a Transient Stability Program Overall structure Structure of machine and network iterative solution Advanced Component Models Synchronous machine saturation Detailed turbine model Induction machines Relays Unbalanced faults 8 System Stability under Power Electronic Control Description of the Algorithm Data flow Modifications required to the component programs Equivalent circuit components Interface variables derivation Quasi Steady-state Converter Simulation Rectifier loads d.c. link Representation of converters in the network Inclusion of converters in the transient stability program Static VAR Compensation Systems Representation of SVS in the overall system

7 9 Fault Level Derivation Short Circuit Analysis System equations Fault calculations 10 Numerical Integration Methods Properties of the Integration Methods Accuracy Stability Stiffness Predictor-Corrector Methods Runge- Kutta Methods 11 Test Systems used in the various topics