As above, this would be spread according to how the units are operated.

Transcription

1 Hydro Update GADS WG Meeting In previous discussions, we had agreed to the following: 1) We agreed to modify the GADS default of a 2% Gross vs Net for hydro. The new default will be 0%. Hydro operators can report Net and Gross if their operation has a significant difference with these two points. 2) We agreed that a plant derate would be allocated to a unit or a combination of units depending on how the reporter would choose to report them. Below is an illustration. Constraint Unit Size 100 MW 100 MW 100MW 240 MW On Off Off A derate is required note 1 On On Off A derate is required note 2 On On On A derate is required note MW Off On Off A derate is required note 4 On Off On A derate is required note 5 On On On A derate is required note 6 note 1 note 2 note 3 note 4 note 5 note 6 In this case, the plant needs to be derated 60 MW. You could choose to derate one unit 60 MW, or split the derate between the two units (i.e. derate 30 MW each, 20 MW on one unit or 40 MW on the other, etc.) This is similar to note 1 except in this case the unit that is not operating would carry the full 60 MW derate. However, you could elect to derate the two operating units and limit their output and reduce the amount of derate on the non-operating unit. As above, this would be spread according to how the units are operated. similar to Note 1, this would require the derate be set on one or split between both of the units. In this case, there is not enough capacity available for the two units to operate so a derate would have to be set on the non-operating unit and the remainder either assigned or divided to the other two operating units. As above, this would be spread according to how the units are operated.

2 Run of River Operation: The GADS WG agreed to the following: When a run of river hydro plant has less flow than full capacity, the unit output is adjusted to accommodate the decreasing flow. As these flows decrease, eventually units will need to be shut down due to lack of water. When this happens, users will be asked to code these under a new event that will be created RUTHh. This new event is defined: Resource Unavailable Turbine-Hours hydro RUTHh The number of turbine hours that the turbines are available but not producing electricity due to the lack of water in a run of river plant operation. In addition to the new event RUTHh, two additional events will also be created for generating assets. These refer to pumping mode and sync condense mode. Sync condense is also to be used with other asset types if they have that capability. These other events are: Pumping Mode Operation Hours - PU The hours a pumping station or pump/turbine unit is operated in a pumping mode Sync Condense Operation Hours CO The hours a unit is in a sync condense operation that is used to support system voltage. For hydro units, this event code can also be used for spinning reserve where the unit is consuming energy from the system (below speed no load). Updated Proposal: Provide specific guidance for hydro operators to report hydro units that are shut down due to a lack of water as a RUTHh Event associated with cause codes 9135 (lack of water) or 9504 (regulatory agency initiated) if units are shut down due to agency required flows that bypass the plant. Provide specific guidance for hydro operators who place a unit in pump mode would report the unit as a PU event associated with cause code 9345 (pump storage operations). Provide specific guidance for generator operators who place a unit in the sync condense mode to report this as a CO event associated with cause code 9340 (Synchronous Condenser Operation). Discussion Points: 1. This recommendation would provide only for those plants that must maintain a constant forebay and cannot draft and fill their reservoir outside any prescribed boundaries. To illustrate, many hydro plants are required to maintain a specific forebay level. If the in-flow is less than full plant capacity, then units will be backed down and eventually shut down due to lack of inflow (i.e. lack of water). The unit capacity will not change and often may have incidental work done on them during these times.

3 a. NOTE: Conditions where a storage project has used up its flexibility will be discussed in the Pulsing or Peaking operation section. 2. It is the practice for some companies to rotate operating hours during these conditions. For these circumstances, the units will be reported in and out of RUTHh throughout the month. 3. If a unit is taken out of service for maintenance purposes, those hours would be recorded as FO, MO, PO, respectively 4. If a unit is required to be ramped down to partial load due to lack of water, this would not result in a de-rating of the unit. 5. We need to investigate how regulatory events (i.e. 9504) are to be interpreted. There are times when hydro units are required to be shut down due to license restrictions. Other times it could be other water demands that are outside of license requirements, but are still agency driven (i.e. irrigation or other water supply needs). The Energy Time Diagram shown below is an expanded version of Ed Tindell s diagram he uses in his GADS training session. In this diagram, the designation of RUTH hours is not specifically identified as part of the available hours or not. (You may need to magnify the image.) Also, this diagram shows negative energy which is reflective of energy coming in from the system to motor these operating conditions. The typical hydro operating scenario diagram is also included to help illustrate the different operating circumstances faced by the GADS data recorder. This is Reference 1. For purposes of this discussion, the operating plant must maintain the absolute max water level in the forebay at all times. It cannot operate in the active storage region shown in this diagram. Questions to the Group: 1. Are RUTHh hours considered available hours? 2. What are the implications to the equations? 3. Is incidental maintenance work acceptable with this event? 4. Are we OK with not de-rating a unit even though there is not enough water to run at full capacity? (This would largely be an academic exercise.) New Item: Peaking or Cycling Operation Proposal: Provide clarity to hydro operators on the difference between this plant operation and run of river operation and to report these events as RS. Discussion Points 1. This is similar to the way we ask gas turbines to report their cycling operations. Decisions here need to be made in context with gas turbines 2. One characterization here is a time element. This assumes that dispatch could operate one or multiple units at any output up to their GMC=NMC for a period of time. We may want to discuss what that period of time is.

4 a. One example: we would typically operate a unit or multiples (depending on water) several hours each week day during peak periods and then shut down and replenish the active storage. We might do this through the week days and not run during the week ends to regain the active storage. b. Other uses are to bridge the time required to bring other resources on-line c. In an unplanned event, we might put units on line to an emergency response to hold on until other plant can be started or energy purchases can be made. In these cases, we may run out of storage relatively quickly, but can shut down and re-charge the storage again. 3. Consider if we change requirements to consider only reporting the hours operated. Continue to record the number of starts (and failed starts) of these peaking units. We need to ask the benefit of the timing of all of these events. This would save a lot of work for reporters. Again, could this apply to gas turbines? 4. For some, this operation is also used as AGC, Load Following, or Regulation. This would all be part of this type of operation. 5. As discussed above, impacts to the EFORd calculation have been raised if we do something different than ask for the RS. 6. When the active storage is depleted and it is no longer being filled, the operation would move to a Run of River type operation as described in that scenario. 7. All units that are not in an outage (FO, PO, MO) or in sync condense or pump would be considered fully available even though dispatch may not choose to operate a unit. To help illustrate this operation, see Reference 2. In this picture, there is an active storage element of a project (can be hourly, daily, weekly, monthly, seasonal) that can be used and recharged as needed by dispatchers. Also attached with this reference is a chart of seven days of operation at one of our hydro facilities illustrating this scenario. New Item: Changes in Operating Head The output of a hydro unit pump/turbine or conventionall turbine is a function of the available head to the unit. The head on a plant can vary seasonally, monthly, weekly, daily, and even hourly. Trying to capture this level of detail is an exhasutive and perhaps unnecessary. Proposal: hydro owners adjust the NMC and NDC (which are typically the same) based on the change in monthly head. Discussion: This intended to be reflective of any change in operating head due to changes from seasonal operations, adjusted monthly. This is not intended to be a mathematical exercise to determine a mean or median rating, rather a rating based on the best judgement of the reporter. Some examples can include: 1. An operation where a reservoir is weekly cycled but returned to a near normal level each week. In this case, no change in NMC/NDC would be warranted.

5 2. If a reservior was pulled down during the winter months to make room for a spring re-fill, it would make sense to generally account for the changing level for both the withdrawl and recharge of the reservoir. In this case, a change in NMC/NDC would be warranted. 3. If a significant rain or storm event was expected and reservoirs were drawn down for flood control. Typically this operaiton is short lived and reservoirs are returned to normal soon after the storm/rain event. In this case, no change in NMC/NDC would be warranted. All of these require some judgement by the reporter. Discussion Points: 1. This is considered an ambient condition. 2. How is variable wind handled. Is this comparable to that? 3. The same questions about how much to change the output of the unit apply to gas turbines and temerature adjustments. What are the expectations of this requirement? a. Average temperature? b. Average high temperature? c. High Temperature for the Month? d. Others? 4. Would it be prudent to provide some specific mathematical formula to determine the head and subsequent rating.

6 Reference 1 Typical Hydro Operating Scenarios Run of River Freeboard or absolute max water level Operating Levels or Active Storage Max Head Constant Forebay Level (Run of river) Min Head Minimum Reservoir Level Tailwater Levels

7 Reference 2 Typical Hydro Operating Scenarios Peaking or Pulsing Freeboard or absolute max water level Operating Levels or Active Storage Max Head Operate Reservoir between these levles Min Head Minimum Reservoir Level Tailwater Levels

8 Representative Graph of Active Reservoir Use

9 Exhibit 1 Energy Time Diagram with RUTH Seasonal Derate Average In Service Derate In Service Derating Derating During RS Net Maximum Capacity Net Dependable Capacity Net Available Capacity Average Spinning Reserve Average Load In Service Descretionary Load Reduction In Service Actual Generation Reserve Shutdown Pump Hours Sync Condense Hours RUTHh Hours Forced Outge Maintenance Outage Planned Outage Note negative energy SH RSH PU CO RUTHh UOH MOH POH AH??? UH SOH PH Abbreviations: AH - Available Hours MOH - Maintenance Outage Hours PH - Period Hours POH - Planned Outage Hours RSH - Reserve Shutdown Hours SH - Service Hours SOH - Scheduled Outage Hours UH - Unavailable Hours UOH - Forced Outage Hours

10