Full Equations (FEQ) Model for the Solution of the Full, Dynamic
Equations of Motion for One-Dimensional Unsteady Flow in Open Channels
and Through Control Structures
Purpose: The operation rules for any dynamically operated control structures are given with this block. This block is only required if SOPER=YES in the Run Control Block (section 13.1). The maximum number of Operation-Control Blocks allowed in FEQ is specified in the parameter MNBLK in the INCLUDE file ARSIZE.PRM (appendix 3). This number may be increased as necessary and FEQ recompiled.
Heading: One line of user-selected information. The suggested string
is OPERATION OF CONTROL STRUCTURES.
LINE 1
Variable: BLK
Format: 4X, I5
Example: BLK=00001
Explanation: BLK is the number of the Operation-Control Block table.
The input of operation blocks is terminated if BLK= - 1. Operation-Control
Block tables must be numbered consecutively, beginning with 1.
LINE 2
Variable: BLKTYP
Format: 8X, A4
Example: BLKTYPE=PUMP
Explanation: BLKTYP is the type of the Operation-Control Block. Two
types of operation blocks are used: BLKTYPE=PUMP denotes that a pump is
controlled, and BLKTYPE=GATE denotes that a gate is controlled.
LINE 3
Variable: MINDT
Format: 6X, F10.0
Example: MINDT=300.
Explanation: MINDT is the minimum time, in seconds, between changes
to the gate or pump setting. Changes in the setting can be made only at
the boundary between time steps, but at least MINDT seconds must have elapsed
since the last change before the next change can be made.
LINE 4
Variable: PINIT
Format: 6X, F5.0
Example: PINIT=0.62
Explanation: PINIT is the initial value for the opening fraction. The opening fraction varies between 0 and 1. When PINIT=0, the gate is completely closed (underflow gates: sluice gates, tainter gates, and others) or fully raised (overflow gates: drum gates and related devices). The gate is so positioned to either force the flow to zero or reduce it to a minimum value. When PINIT=1.0, the gate is positioned such that the flow is maximized for the given water-surface elevation.
For a pump, opening-fraction values specify the speed of the pump relative
to the standard speed chosen for the table defining the relation between
flow and head for the pump. The pump is off when PINIT=0.0, and the pump
is on at the relative speed given if PINIT > 0.
If BLKTYPE=GATE (Gate Operation)
LINE 5
Variable: HEAD
Format: A80
Example:
BRAN NODE KEY MODE MNRATE LRATE LOWLIM HGHLIM HRATE LPRI NPRI HPRI DPDT
Explanation: These are user-supplied headings for subsequent information.
LINE 6 (one for each control point)
Variables: BRA, NODE, KEY, MODE, MNRATE, ML, LL, LU, MU, LPRI, NPRI, HPRI, DPDT
Format: I5, 2A5, I5, 5F7.0, 3I5, F5.0
Explanation:
The parameters defining a control point used in the operation of a structure are specified on this line.LINE 6a (one for each case where KEY=QVAR on Line 6)BRA is the branch number for the control point. BRA=0 if the node is a flow-path end node.
BRA < 0 denotes the end of input for the current block.
NODE is the node label for the control point.KEY=ELEV if water-surface elevation is monitored at the control point, KEY=QCON if flow rate is monitored at the control point and the null zone limits are constant values, and KEY=QVAR if flow rate is monitored at the control point and the null zone limits are variable. The null zone is that range of the monitored value (flow or elevation) in which the setting of the structure will not be changed.
In the QVAR option, the gate will be operated so that the outflow will follow the variable null zone closely if the outflow changes slowly enough. If the null zone changes rapidly, the simulation may not be able to follow the null-zone changes because of inadequacies in the rules for opening the gate or in the head available. The QVAR rule may be overridden by other rules on the basis of the priority of the various control points.
MODE=0 means that the structure opening is changed whenever the monitored value at the control point is outside the null zone. MODE=1 means that the structure opening is changed only if the monitored value at the control point is outside the null zone and is not moving in the right direction with sufficient speed.
MNRATE is the minimum change per hour under MODE=1 required to avoid changing the structure opening. For example, if KEY=ELEV, indicating that water-surface elevation is monitored, and if MNRATE=0.01, then the elevation at the monitored point must be moving toward the null region at a rate exceeding 0.01 ft/hr to avoid changing the structure opening.
The null region is needed to prevent or minimize searching for the structure's opening fraction. Thus, the action indicated in the null region is no change in the opening fraction. Experience indicates that MODE=1 is the best choice because the response at the control point to the structure-opening change can be delayed so that conditions at the control point are still out of the null zone but are moving toward the null zone. If MODE=0 is used, the structure-opening fraction will increase to the maximum value, resulting in a large overshoot of the desired result. This will then be followed by a decrease in the structure opening to its minimum value and another overshoot of the desired result. Use of MODE=1 and a properly sized null zone can reduce the search for the opening fraction.
ML is the rate factor for the rate of change of opening when conditions at the control point are below the null zone. This rate factor is a multiplier on the distance of the monitored value from the closest boundary of the null region. The resulting rate is the change per hour of the structure opening as measured by an opening fraction, p, which is taken as 0.0 when the flow is restricted by the maximum amount and as 1.0 when the flow is restricted by the minimum possible amount. The actual rate of opening used is limited by DPDT, given later in the input. The rate-factor sign is determined by the location and design of the control structure relative to the control point.
LL is the lower limit for the null zone. LU is the upper limit for the null zone.MU is the rate factor for the rate of change of opening when conditions at the control point are above the null zone.
LPRI is the numerical priority of the action for this control point when the monitored value is below the null zone. Numerical priority 1 is the highest priority, 2 is next highest, and so forth. The numbers are ordinal only; that is, used only for relative ranking. There is no degree of priority difference, so the only relation used is the quality of equal to, greater than, or less than.
NPRI is the priority of the action for this control point when the monitored value is in the null zone.
HPRI is the priority of the action for this control point when the monitored value is above the null zone.
DPDT is the absolute value of the maximum permitted rate of change in the opening fraction for the structure.
Variable: HEAD
Format: A80
Example: NUMB NZHW NODE NDWT NODE NDWT NODE NDWT
Explanation: These are user-supplied headings for subsequent information.
LINE 6b (one for each case where KEY=QVAR on Line 6)
Variables: NUMB, NZHW, (NDVEC(J), NDWT(J), J=1,NUMB)
Format: I5, F5.0, 7(I5,F5.0)
Explanation:
The values required to define the variable null-zone limits are specified on this line.If BLKTYPE=PUMP (Pump operation)NUMB is the number of flow-path end nodes used in computing the flow to define the midpoint of the null zone.
NZHW is the null-zone half width. The null-zone half width is added to the midpoint flow for the null zone to specify the upper limit of the null zone. It is subtracted from the midpoint flow to give the lower limit.
NDVEC specifies the numbers of the NUMB flow-path end nodes that are used to compute the midpoint of the null zone.
NDWT is the weight used for the flow at each flow-path end node for computing the midpoint of the null zone. This weight can be positive or negative. The weight on the flows at the flow-path end nodes can be used to deduct flow leaving the stream system by some path other than the structure being operated in the control block. In addition, the weight can be used to account for other sources of inflow, such as diffuse inflow not considered at any flow-path end node. As the heading indicates, the flow-path end node and the associated weight are given pairwise in the input.
LINE 5
Variable: HEAD
Format: A80
Example: BRAN NODE KEY MNRATE RISE FALL ONPR OFPR
Explanation: These are user-supplied headings for subsequent information.
LINE 6 (one for each control point)
Variables: BRA, NODE, KEY, MNRATE, RISE, FALL, ONPR, OFPR
Format: I5, 2A5, F7.0, 4I5
Explanation:
The parameters defining a control point used in the operation of a variable-speed pump are specified on this line.A dynamically operated structure can include more then one control point, and different actions may be indicated by levels at the various control points. The method used in FEQ simulation to determine which action should be taken is to attach a priority to each of the three possible actions indicated by levels at the control point. The highest priority action for all the control points is the action taken.BRA is the branch number for the control point. If the node is a flow-path end node, BRA=0 because the node label will provide complete information on the node location. BRA < 0 denotes the end of input for the current block.
NODE is the label for the node at control point.KEY=ELEV if water-surface elevation is monitored at the control point, and KEY=QCON if flow rate is monitored at the control point. Pump control does not permit a variable-width null zone as for gates when KEY=QVAR is specified. The null zone is that range of the monitored value (flow or water-surface elevation) in which the setting of the pump will not be changed.
MNRATE is the minimum change per hour in the monitored variable (flow or water-surface elevation) required to change the table defining the pump operation. Two pump-operation tables are considered: one for a rising level at the control point and one for a falling level. The level must have been moving at least as fast on the average as the rate given in MNRATE before the computed level is considered to be really rising or falling. This tolerance is included to prevent rapid switching between the tables.
RISE is the number of the table specifying the pump speed as a function of the monitored variable when the level is increasing in magnitude. This function includes the definition of the null zone for the pump. A discussion of the pump-speed function is presented in section 8.1.2.2.3.2.
FALL is the number of the table specifying the pump speed as a function of the monitored variable when the level is decreasing.
ONPR is the priority assigned to the control-point action when the pump-speed function indicates that the pump be turned on.
OFPR is the priority assigned to the control-point action when the pump-speed function indicates that the pump be turned off.
Application of the simple priority method for selecting the proper action
ignores the direction of motion of the monitored values. Sometimes the
action taken when the monitored value is increasing differs from that when
the monitored value is decreasing. This complication has been included
for pump control but not for gate control. The number of rules used for
the operation of control structures is virtually unlimited. Thus, changes
will be necessary for specific examples not fitting the current generalized
scheme.