Introduction Value of wind power Market value of wind power References ECE 566: Grid Integration of Wind Energy Systems S. Suryanarayanan Associate Professor ECE Dept. Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Value of a power plant Market value of wind power References Value of a power plant [1] A power plant‘s objective is to provide electricity to the load with the following characteristics: Cheap Reliable Clean, where applicable and mandated by law Depending upon the types of fuel and control system, different plants may have different characteristics General notion: The value of a new power plant is equal to the marginal value of the plant in the existing power system Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Value of a power plant Market value of wind power References Parts of a power plant‘s value [1] Operating cost value Capacity credit Control value Loss reduction value Grid investment value Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Value of a power plant Market value of wind power References Parts of a power plant‘s value [1] Operating cost value This is defined as the new power plant to decrease the operating costs in the existing power system If a new plant is connected to the grid, it will have a finite amount of power that it can supply This implies that the production from the existing (rest of the) plants in the system/grid will decrease As a consequence, the operating costs of the existing plants will decrease (as these costs are tied to the output) Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Value of a power plant Market value of wind power References Parts of a power plant‘s value [1] Capacity credit This is defined as the ability of a new power plant to increase the reliability in the existing power system In the existing system, there is the risk of a capacity shortfall This shortfall is measured using the metric loss of load probability (LOLP) LOLP is defined as the probability of the electricity supply not meeting the demand in the grid This metric is grid-specific and when this value is high, loads have to be disconnected to keep the grid stable By adding new power plants to the existing grid, this metric can be lowered Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Value of a power plant Market value of wind power References Parts of a power plant‘s value [1] Control value This is defined as the ability of a new power plant to follow the load with some fidelity Loads and variable sourced generation change over time with different time signatures If a new plant added to the grid lowers supply-demand imbalance in the system, then its control value is considered positive If a new plant added to the grid increases supply-demand imbalance in the system, then its control value is considered negative Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Value of a power plant Market value of wind power References Parts of a power plant‘s value [1] Loss reduction value This is defined as the ability of a new power plant to lower the overall losses in the existing T&D system Proximity of the new plant to the load center plays a significant role This means that the new plant, which is located geographically/electrically closer to the customers, than existing plants, possesses a positive value in reducing delivery losses If the new plant increases the losses in delivery, then this value is negative Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Value of a power plant Market value of wind power References Parts of a power plant‘s value [1] Grid investment value This is defined as the ability of a new power plant to decrease the need for future grid investments Also known as capacity deferral A new plant located in proximity to a load center with high projected growth has a positive grid investment value, since the proximity decreases the need for investments in delivery infrastructure And, vice versa Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Operating cost value of wind power [1] Refers to the capability of wind power to decrease operating costs of the other sources in the system This value corresponds to the value of 1kWh produced from WECS which replaces that exact quantity of energy from another source Typically, wind power replaces fuel-based thermal power plants either directly or via a storage step In thermal plants, the lowest cost units are fired first. So, wind power normally replaces the highest cost units when storage is applied. This reduces the overall operating cost of the system. Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Capacity credit of wind power [1] Refers to the capability of WECS to increase system reliability or the capability of WECS to replace other power sources while maintain the same levels of security and reliability [2] To understand capacity credit, we must define Loss of Load Probability (LOLP) [3] LOLP is the probability that the equivalent load E (i.e.,sum of physical load D and all outages in the system O tot ) exceeds the available generation ˆ G tot � � � � D > ˆ E > ˆ P G tot = P G tot (1) Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Capacity credit of wind power [1], [3] Acc. to [3], capacity credit may be defined in 3 ways: Equivalent firm capacity : of a generating unit g is the 1 capacity of a fictitious 100% reliable unit which results in the same LOLP decrease as the unit g Load carrying capacity : of a generating unit g is the 2 ability of that new unit to allow the system to increase its loadability without compromising adequacy of generation Equivalent conventional power plant : of a generating 3 unit g is the same as the Equivalent firm capacity , except that in this case the unit g does not have a 100% reliability, but has that of a conventional power plant Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Capacity credit of wind power [1]. Figure from [1] Let us look at an example from [1] Real hourly load for the week of Jan 2, 2003 from W. Denmark Available capacity is set to 3250MW Without wind in the system, the total deficit duration for that week is 40 hours Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Capacity credit of wind power [1]. Figure from [1] Available capacity increases when 1994MW of wind is added to the system Mean wind power during the week of Jan 2, 2003 is 392MW; and mean weekly production for that area was 396MW (i.e., selected week is representative) With wind in the system, the total deficit duration for that week is 27 hours, thus increasing reliability Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Capacity credit of wind power [1]. Figure from [1] If load increases by 300MW each hour in that week, the total deficit duration will increase to 40 hours This means, the load carrying capacity is 300MW, i.e., the capacity credit is 300MW Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Capacity credit of wind power [1] Capacity credit when there are situations with no wind In the previous example, for an installed capacity of 1194MW, the capacity credit is 300MW, i.e., 15% of installed capacity Like with other power sources, there is a finite probability that the plant may be unavailable (i.e., wind will not blow as expected) during some peak times The example showed the drop in total deficit duration (by 13 hours) but not to 0 hours with increases in wind power No matter the installed wind power capacity, when the wind is not blowing the capacity credit is 0 Larger window lengths of time are required for drawing credible conclusions on capacity credit Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Capacity credit of wind power [1] What about the capacity credit when there are situations with no wind? Mean weekly production in the example was 392MW Annual power production: 396MW × 365 × 24hours = 3469GWh If a thermal plant with capacity factor of 92% (because it is taken out of service for 4 weeks in a year for maintenance), then its rating to produce the same amount of energy as the wind plant is: 3469 × 100 1 92 × 8760 = 429MW The capacity credit for this thermal plant is 429MW The capacity credit for the wind plant was 300MW, i.e. 70% of that of the thermal plant Suryanarayanan ECE 566 Lecture/Week 11
Introduction Value of wind power Market value of wind power References Control value of wind power [1] Refers to the capability of wind power to participate in balancing supply and demand The balancing is done differently depending on the time frame: Primary control : seconds up to 1 minute 1 Secondary and tertiary controls : from end of primary 2 control time frame up to 1 hour Daily and weekly controls 3 Seasonal control 4 Multi-year control 5 Suryanarayanan ECE 566 Lecture/Week 11
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