Correction: Yang, W.; Yang, J.; Guo, W.; Zeng, W.; Wang, C.; Saarinen, L.; Norrlund, P. A Mathematical Model and Its Application for Hydro Power Units under Different Operating Conditions. Energies 2015, 8, 10260–10275

The authors wish to make the following corrections to the published paper [1].

• Equation (15) is replaced with:

  $$b_p{K}_d\frac{{{dy}_{PID}}^2}{d^{2}t}+(1+b_p{K}_p)\frac{{dy}_{PID}}{dt}+b_p{K}_i(y_{PID}-y_c)=-\left(K_d\frac{{{dx}_f}^2}{d^{2}t}+K_p\frac{d{x}_f}{dt}+K_i{x}_f\right)$$
• Equation (16) is replaced with:

  $$e_p{K}_d\frac{{{dp}_g}^2}{d^{2}t}+e_p{K}_p\frac{d{p}_g}{dt}+e_p{K}_i(p_g-p_c)+\frac{d{y}_{PID}}{dt}=-\left(K_d\frac{{{dx}_f}^2}{d^{2}t}+K_p\frac{d{x}_f}{dt}+K_i{x}_f\right)$$
• Equation (17) is replaced with:

  $$b_p{K}_d\frac{d{(y_{PID}-y_c)}^2}{d^{2}t}+(1+b_p{K}_p)\frac{d(y_{PID}-y_c)}{dt}+b_p{K}_i(y_{PID}-y_c)=0$$

• Table 3. Status of selectors in different control modes.

  Control Mode	Equation	S1Status	S2Status	S3 Status
  Frequency control	(15)	1	1	1
  	(16)	1	3	3
  Opening control	(17)	2	1	1
  	(18)	2	2	1
  Power control	(19)	2	3	3
  	(20)	2	2	3

  is replaced with:
• Figure 3 is replaced with:

We apologize for any inconvenience caused to the readers by these changes. The manuscript will be updated and the original will remain available on the article webpage.