Techical Issues IPP in Villages

Replies to This Discussion

Permalink Reply by Don Eller on March 9, 2010 at 6:23pm

Safety- that goes without saying but the new electronic tie in devices pretty much eliminate that.
Costs- Utility is only going to compensate energy provider for avoided costs, IE the fuel not consumed not the price billed per KWh.
Scale- While a 2KW IPP can go on and off line in a utility with a 200kw load without being noticed, if 3 10KW IPPs go on and off line in a system with a 90KW load its going to create havoc.

Permalink Reply by Martin Leonard III on March 9, 2010 at 6:37pm

Understand the safety and the net metering /feed-in tarriff / cost issues...

I've heard lots about scale - primarily the load balancing issues as you related to Don. How do we fix that?

ML


Don Eller said:

Safety- that goes without saying but the new electronic tie in devices pretty much eliminate that.
Costs- Utility is only going to compensate energy provider for avoided costs, IE the fuel not consumed not the price billed per KWh.
Scale- While a 2KW IPP can go on and off line in a utility with a 200kw load without being noticed, if 3 10KW IPPs go on and off line in a system with a 90KW load its going to create havoc.

Permalink Reply by Martin Leonard III on March 9, 2010 at 7:33pm

I just looked at the AEA Wiki and reviewed their Diesel Working Group Recommendations

Are we, as a state, addressing load balancing and switching issues as related to this discussion? Are we able to empower local residents to become part of the solution?

Ask Germany about how that is done.

Permalink Reply by Don Eller on March 10, 2010 at 9:57am

How does one resolve the plight of both the IPP and the utility when the IPP/s is generating a significant portion of the utilities load? This is actually much more of a regulatory and policy issue than a technical one. A electrical utility is obligated by law to serve all the customers in its service area. The utility has invested in the infrastructure required to provide its customers with service, so when a user becomes a producer it creates problems because that is not the way the electrical system was designed.
If IPPs could and would make a commitment for providing a known quanity of energy for known duration it would make it significantly easier for the utility to accomodate the energy of the IPP. However if the IPP is going to provide an uncertain amount of energy at uncertain times it makes it very difficult for the utility to meet its own legal obligations and make use of the IPP's energy. For the utility must have everything in place to meet its legal obligation to serve and then also accomodate an intermitent energy source, so the IPP energy becomes an "issue" the utility has to deal with rather than a low cost source of energy.

Suggestions for IPP interconnection issues:
1) IPPs need to provide a known predictable consistent energy source.
2) Utilities and IPPs need to coordinate from IPP project inception.
3) Work with a utility that is IPP friendly.

Permalink Reply by Alan Fetters on March 10, 2010 at 11:21am

Hello Martin

I offer a broad shotgun response similar to Don’s. Again safety is always top priority.

Some of the technical opportunities that come to mind for IPP’s on a small grid include the penetration percentage, phasing (single, poly or 3), location on the grid, other IPP’s on the grid, dispatchable load, black start, grid interactivity, reliability, and predictability. If an IPP produces more than 15-25% of the grid demand at any given time stability of the grid must be considered. Keep in mind the grid is an interconnected power system. Changes to any part of the system cannot be made without considering how they influence the other components of the system. Diesel generator sets have efficiency curves. If the demand changes push the Utility’s diesels into producing power less efficiently then the benefit of the IPP’s power can be reduced.

Another opportunity for the Utility responsible for serving the customer area is continued financial viability. Numerous small rural utilities are struggling financially. If a large customer, such as a school, self generates it can put the Utility in jeopardy and the rate for residential customers can move upward. The Utility must be able to buy power from an IPP at rate less than it costs them to produce utilizing their existing generation infrastructure. The utility must also have the continued cash flow to maintain the existing generation and distribution infrastructure. The Utility must carefully consider all expenses like fuel, operations, maintenance, along with renewal and replacement of it existing infrastructure.

Small IPP’s do not have the same regulatory responsibility to serve the entire customer area and provide continuous, reliable and stable power. IPP’s cannot expect the Utility to pay anywhere near the same rate as the Utility charges. A few self generating customers sometimes unrealistically expect the utility to pay the same rate as they charge and the Utility to still be able to meet their power needs immediately when their self generated power is offline.

Another non technical item is the Utility’s tariff structure for IPP’s. Some are fully regulated by the RCA others have little regulation and just a certificate. Some have polices and tariffs for IPP’s other do not.

All of the projects that we have been involved in that have successfully integrated a substantial portion of alternative energy into rural grids have modern PLC controls and SCADA systems that are tied together and communicate their status and condition to each other in real time. Based on real time information the control logic can dispatch the appropriate generation and level to meet demand. In some cases dispatchable load such as an electric boiler is needed for successful integration.

Permalink Reply by David Karabelnikoff on March 12, 2010 at 10:24am

Hey Martin,

I'll just post some slides from my professor in smart grids; he's developing smart grid protocols, policy and technology for the EU. I have about 10 here is 3

Attachments:

• DG and Micro genaeration Impact Lopes.pdf, 12.9 MB
• Integrated Management of Storage Systems Lopes.pdf, 6.9 MB

Permalink Reply by Martin Leonard III on March 21, 2010 at 1:39pm

I'm reposting this from Steve...this is the kind of discussion I would like to facilitate...what are the technical issues around rural residential IPPs...and more importantly, how do we begin to address these issues, both in the long term and short term, and start empowering rural residents to be part of the solution.

FYI...We started a new group for discussion of ALL the political nuances...please repost the political threads here - there if you can.

Quyana ML

Thanks Steve.

___________


Comment by Steve Drouilhet on March 18, 2010 at 8:47am
Martin,

There are at least the following technical issues associated with connecting multiple small distributed renewable generators to a village diesel power system:

1. Small PV or wind installations are generally single-phase systems. The utility diesel power plant is inherently three-phase. When individual residential generators start feeding in power (or subtracting load) on individual phases, it becomes very difficult to keep the load balanced among all three phases. An unbalanced load causes the diesel generators to operate inefficiently and makes it difficult to maintain proper voltage on all three phases. This problem can be solved using a central load balancing inverter that will dynamically balance the three-phase load seen by the diesel power plant.

2. Because of the intermittency of renewables, the utility power plant and distribution system must still be sized to meet the peak load with no contribution of the renewables. With IPPs effectively reducing the average load on the system, the utility's infrastructure will operate at a lower load factor (percentage of its rated power). This causes the utility both to lose revenue and operate less efficiently. The utility doesn't mind when they own the renewable generation, since they don't lose revenue, and the decreased load factor on the diesel plan is more than made up for in fuel savings.

3. An objection that used to be raised frequently was that it would be difficult to ensure lineman safety if a bunch of independent power producers were connected to the distribution system and could potentially backfeed the lines when they were supposed to be de-energized for maintenance. With the advent of interconnection standards such as IEEE-1547, which effectively prevent such occurences, this has become a total non-issue.

4. Many Alaska village power plants are still manually operated. The operator knows the daily load profile and can operate the plant fairly efficiently with just a few diesel dispatch decisions per day. When you start adding renewables to the mix (especially wind), the variations in net load become larger and less predictable. To keep the diesel plant operating efficiently requires that it be automated. The system supervisory controller continually monitors the net load and dispatches the diesel generator that can meet that load most efficiently. This is why that in every wind-diesel village power project of medium to high wind penetration, the first step is always to automate the diesel plant.

As David K says, utilities do indeed often have a conservative mindset and tend to oppose change that threatens their monopoly on generation. But there are real technical issues raised by distributed renewables, especially on small isolated mini-grids. Nevertheless, just because it raises issues for the utility doesn't mean it shouldn't be allowed. It is good for the environment and good for the consumer. The village utilities will have to learn how to adapt, just as the big utilities had to learn how to adapt to wind and solar farms on their distribution grids.

Permalink Reply by Martin Leonard III on March 21, 2010 at 2:25pm

Questions in response to Steve's comment:

1) Load balancing inverter...what do they look like? What are the technical configurations? Examples?

2) I have seen hybrid power plants with multiple sized generators acting as an efficient single unit. What would one look like with the automation to enable residential IPPs.

3) I agree...manufacturers of grid tie PV and Wind systems have addressed the safety issues...it is not part of the argument anymore.

4) I understand the net load issues with renewables...glad to hear that technical solutions exist...a prerequisite is obviously vision and foresight.

just because it raises issues for the utility doesn't mean it shouldn't be allowed. It is good for the environment and good for the consumer. The village utilities will have to learn how to adapt, just as the big utilities had to learn how to adapt to wind and solar farms on their distribution grids.
couldn't have said it better myself...

ty Steve!


Martin Leonard III said:

I'm reposting this from Steve...this is the kind of discussion I would like to facilitate...what are the technical issues around rural residential IPPs...and more importantly, how do we begin to address these issues, both in the long term and short term, and start empowering rural residents to be part of the solution.
FYI...We started a new group for discussion of ALL the political nuances...please repost the political threads here - there if you can.
Quyana ML

Thanks Steve.

___________


Comment by Steve Drouilhet on March 18, 2010 at 8:47am
Martin,

There are at least the following technical issues associated with connecting multiple small distributed renewable generators to a village diesel power system:

1. Small PV or wind installations are generally single-phase systems. The utility diesel power plant is inherently three-phase. When individual residential generators start feeding in power (or subtracting load) on individual phases, it becomes very difficult to keep the load balanced among all three phases. An unbalanced load causes the diesel generators to operate inefficiently and makes it difficult to maintain proper voltage on all three phases. This problem can be solved using a central load balancing inverter that will dynamically balance the three-phase load seen by the diesel power plant.

2. Because of the intermittency of renewables, the utility power plant and distribution system must still be sized to meet the peak load with no contribution of the renewables. With IPPs effectively reducing the average load on the system, the utility's infrastructure will operate at a lower load factor (percentage of its rated power). This causes the utility both to lose revenue and operate less efficiently. The utility doesn't mind when they own the renewable generation, since they don't lose revenue, and the decreased load factor on the diesel plan is more than made up for in fuel savings.

3. An objection that used to be raised frequently was that it would be difficult to ensure lineman safety if a bunch of independent power producers were connected to the distribution system and could potentially backfeed the lines when they were supposed to be de-energized for maintenance. With the advent of interconnection standards such as IEEE-1547, which effectively prevent such occurences, this has become a total non-issue.

4. Many Alaska village power plants are still manually operated. The operator knows the daily load profile and can operate the plant fairly efficiently with just a few diesel dispatch decisions per day. When you start adding renewables to the mix (especially wind), the variations in net load become larger and less predictable. To keep the diesel plant operating efficiently requires that it be automated. The system supervisory controller continually monitors the net load and dispatches the diesel generator that can meet that load most efficiently. This is why that in every wind-diesel village power project of medium to high wind penetration, the first step is always to automate the diesel plant.

As David K says, utilities do indeed often have a conservative mindset and tend to oppose change that threatens their monopoly on generation. But there are real technical issues raised by distributed renewables, especially on small isolated mini-grids. Nevertheless, just because it raises issues for the utility doesn't mean it shouldn't be allowed. It is good for the environment and good for the consumer. The village utilities will have to learn how to adapt, just as the big utilities had to learn how to adapt to wind and solar farms on their distribution grids.