Software modules for pipe network planning

PSS®SINCAL

Calculations for different pressure levels

PSS®SINCAL Gas calculates the flow conditions in meshed networks with different pressure levels. It is possible to perform steady-state as well as dynamic calculations. The effects of time events or time series on network performance can be displayed as a function of location in various graphs.

With the aid of dynamic simulation, it is possible to observe different states and changes of state in the network at certain times. In this way, it is also possible on the basis of predetermined time series (for consumers, supply, control, etc.) and time events (valve position, consumer shut-off etc.) to calculate values for quantities, flows and pressures in the network.


Hydraulic calculations

The program can handle all steady-state pressure, volume and temperature distribution in meshed networks.

Features

  • The program works according to the Hardy-Cross Method and the second rule of Kirchhoff.

  • For lambda calculations there is a choice between Nikuradse’s or Prantl-Colebrook’s or Unger Prantl-Colebrock’s formula.

  • Undersupply
    If the differential pressure is below the minimum pressure although all valves are open, the consumption of the customers will decrease. If required, this effect can be modeled in PSS®SINCAL.

  • Re-dispatch of supply
    It monitors the limits of the supplies and re-distributes the energy between the different sources.

  • Locking of pipes
    Locking of pipes (or other elements) on one or both sides is possible without deleting the elements.

  • Definition of characteristic curves for pumps and valves

  • Checking of the operating points and limits of pumps, valves and network groups

  • Weak point analysis and color-coded identification of the weak points in the network

  • Graphical identification of elements which are affected by pipe failures

  • Definition of specific groups of network elements, e.g. consumer groups with identical behavior

  • Pumps and valves in every network situation, e.g. in loops

Network Elements

  • Nodes
    Geodetic altitudes will be taken into consideration. Coordinates can be entered in the Gauss-Krueger-System.

  • Leakage node
    Only in dynamic calculation. The user can enter starting and ending time of the leakage, output surface (mm 2), pressure and leakage with/without resistance.

  • Generators
    The following infeed types are available:
    - Flow supply: The input flow at the supply remains constant and does not depend on the pressure at the source. Constant supply can be given in Nm 3/h, m 3/h or MW. Initial starting values can be considered for dynamic simulations.
    - Pressure supply: Surplus pressure will be constant at the supply point. It is independent of the load distribution in the network. The pressure supply compensates the difference between the total input at supply points and the total output at the distribution points.

  • Pipes
    Pressure losses are calculated for pipe elements. A data base with appropriate inside diameters of pipes can be defined. The roughness of the pipes, the additional factor for the pipe bend, Zeta, annual roughness increase and annual diameter reduction and leakage will be taken into account during the calculation. Pipe data can be entered for each pipe individually or by reference to a standard type.

  • Locking fittings − sliding valves
    Pipes with a valve for which the diameter of the valve can be regulated. Additionally, the Zeta value can be entered as a function of the valve position. This behavior can be defined in a table/diagram.

  • Check valve
    Pipe with uni-directional flow (from pipe start to end). The diameter is a function of flow velocity. The pressure loss of the check valve is a function of the opening angle which is a function of velocity.

  • Pressure regulator
    This network element regulates the pressure so that the pressure set point will be maintained at a specified node. It can result in a pressure increase or decrease.The set point can be a fixed value or can be dependent of a governor value, the circulation volume.Pressure guards and pressure limitations will be checked.

  • Constant pressure decrease
    A pressure decrease between a start and end point can be defined. The pressure decrease is independent of the output flow.

  • Compressor
    A pressure increase between the start point and the end point can be defined. Any node pressure can be regulated by this element.

  • Line with constant flow
    The flow in the line remains constant and is independent of the load distribution within the network and the pressure.

  • Differential pressure regulator
    This network element maintains a given pressure difference between reference nodes. The point of regulation can be on both sides of the pipe.

  • Pressure buffer
    This element simulates a gas reservoir with overflow. There will be a flow in or out of the pressure buffer. If the pressure is below a defined threshold there will be no consumption. If the pressure exceeds the threshold value the consumption will be calculated in such a way that the pressure equals the defined pressure. In the dynamic calculation the starting pressure will be taken from the steady-state calculation.

  • Consumer
    Consumers create gas flows in pipes which are equivalent to the specified consumption and independent of the pressure. Consumer types with different characteristics can be defined and these types can be assigned to groups of consumers.

Tables and reports
The user can define the content of reports in selection lists.

  • General network data

  • All element data

  • Node reports with pressures (absolute, working, air), altitude and flow (Nm 3/h) and all connected elements with flow, flow speed and pressure difference

  • Pipe elements with flow, pressure, pressure decrease, flow speed, length and diameter etc.

  • Results summaries with minimal and maximum pressure and maximum velocity

Diagrams
Longitudinal section.
The user can define free routes through the network showing the values for

  • Pressure

  • Air pressure

along automatically generated paths.

Network Diagram
Graphical output of following values:

  • Nodes: altitude, consumption, pressure absolute, relative

  • Pipes: flow, pressure absolute, pressure decrease, length, diameter, flow speed

Color-coded filter functions for pressure, flow, speed, consumption, etc.

Load profiles

Time Series
The Load Profile simulation is a special form of flow calculation that allows the simulation of varying consumption or infeed conditions based on chronological profiles, e.g. daily profiles in 15-min time steps.

For this task, in addition to their nominal data the consumer and infeed models include an assigned load/infeed profile which can be defined in absolute or relative values.

Based on the specified nominal data and time series the gas flows in the network are calculated. The time series analysis also allows modeling consumption taking into account the effect of simultaneity depending on the number of consumers of identical type. This can be achieved by defining and assigning consumer types.

The outcome of the time series simulation is:

  • The results of flow calculations of all time steps are available, including the analysis of maximum or minimum values (e.g. pressure, etc.).

  • Diagrams showing daily profiles of result data observed at selected nodes and branches in the network.

Contingency analysis

The purpose of the Contingency Analysis module is to assess the performance of the network during outage of network components. The outcome of the contingency analysis is the determination of weak points or conditions that may lead supply interruptions.

Contingency Analysis comprises a series of flow calculations. One or more elements are considered on outage in each individual load flow calculation. PSS®SINCAL can simulate the outage of a single network component or a group of components. Conditional and unconditional outages as well as base and resulting outages can be modeled.

All relevant results (minimum and maximum values, unsupplied consumers, etc.) are recorded and summarized in a clearly arranged results dialog window.

Dynamic simulation

This method calculates the gas transportation time and flow path:

  • Calculation of transportation time and flow path for freely defined consumers.

  • Results can be displayed graphically.

  • Flow paths through the network are determined automatically, even in meshed networks.


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